Syringomyelia (SM) and the
Cavalier King Charles Spaniel
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IN SHORT - IN DEPTH
- CM - OH - COMS
- Chiari-like malformation
- - CM research history
- -CM recent findings
- - pain due to CM
- What SM Is
- Symptoms
- Diagnosis
- - MRIs
- - CTs
- - thermography
- - ultrasound
- - BAER
- MRI Clinics
- DNA Testing
- Progression
- Treatment
- - drugs
- - alternative care
- - surgery
- - soundwave therapy
- Current Research
- Seminars
- Breeders' Responsibilities
- What You Can Do
- Related Links
- SM in Other Breeds
- Veterinary Resources
IN SHORT:
Syringomyelia (SM) is an extremely serious condition in which fluid-filled cavities develop within the spinal cord near the brain. It is also known as "neck scratcher's disease", because one of its common signs is scratching in the air near the neck.
The back half of the cavalier King Charles spaniel’s skull typically may be too small to accommodate all of the brain’s cerebellum, which may also be too large, and so it squeezes through the foramen magnum – the hole at the back of the skull – partially blocking the flow of cerebrospinal fluid (CSF) down the spinal cord. The variable pressure created by the abnormal flow of CSF is believed to create the SM cavities – called syrinx – in the spinal cord.
SM is rare in most breeds but has become very widespread in cavalier King Charles spaniels. The number of diagnosed cases in cavaliers has increased dramatically since 2000. Researchers estimate that up to 95% of CKCSs have Chiari-like malformation (CM or CLM) – also known as caudal occipital malformation syndrome (COMS) or occipital hypoplasia (OH), the skull bone malformation present in all cases and believed to be at least part of the cause of syringomyelia – and that more than 50% of cavaliers have SM. The severity and extent of syringomyelia also appear to get worse in each succeeding generation of cavaliers. It is worldwide in scope and not limited to any country, breeding line, or kennel, and experts report that it is believed to be inherited in the cavalier. More►
Symptoms
SM seldom can be detected in young puppies, as symptoms of it usually are not evident before the age of six months or years later.
Pain is the most important clinical sign of the disorder. Symptoms
may vary widely among different dogs, but the earliest sign often is that
the dog feels a hypersensitivity in its neck area, causing in some an uncontrollable
urge to scratch at its neck and shoulders. Then usually follows severe pain
around its head, neck, and shoulders, causing it yelp or scream.
Click here
or the YouTube logo to see videos of cavaliers with SM symptoms. As the
disease progresses, it destroys portions of the cavalier's spinal cord, and
is so painful that the affected dog may contort its neck and even sleep and
eat only with its head held high. The dog's legs may become progressively
weaker, so that walking becomes increasingly difficult. Some dogs
deteriorate to the point of paralysis. More►
Diagnosis
The only accurate way of diagnosing the disease is through the use of magnetic resonance imaging (MRI) scanning, an extremely costly procedure. The MRI allows the veterinary neurologist to study the spine for the presence of any abnormality which might obstruct the flow of the cerebrospinal fluid. Accurate MRI results require that the dog be anesthetized. Clinic charges for MRI examinations of canines have been known to vary from a rare discounted rate of $600.00 to over $2,000.00.
The names and locations of veterinary neurologists who are board certified by the American College of Veterinary Internal Medicine (ACVIM) are on our Neurologists webpage.
Another disorder common to cavaliers and with symptoms similar to SM is Primary Secretory Otitis Media (PSOM), which is a highly viscous mucus plug which fills the middle ear and causes the tympanic membrane to bulge. Because the pain and other sensations in the head and neck areas, resulting from PSOM, are so similar to symptoms due to SM, the possibility that the cavalier has PSOM and not SM should be determined before diagnosing SM. More►
Treatment
Treatment options for SM are very limited. Before the disease
progresses to its severe form, the use of cortisteroids, such as
prednisolone, or non-steroidal anti-inflammatory drugs (NSAIDs, such as
Rimadyl and
Metacam) may relieve the symptoms but not the deterioration.
Cortisteroids have serious side effects, such as weight, gait, and skin
changes, and harmful suppression of the immune system. Long term use
of these drugs is not advised.
Anticonvulsants, such as gabapentin (Neurontin, Gabarone), have been successful in some more severe cases, but they may be very expensive. Pregabalin (Lyrica), amitriptyline (Elavil, Tryptizol, Laroxyl, Sarotex), and oral opioids (pethidine or methadone) are alternatives. Methylsulfonylmethane (MSM) is recommended by some veterinary neurologists as a dietary supplement.
Drugs which reduce the production of cerebrospinal fluid, including proton pump inhibitors such as omeprazole (Prilosec), and the diuretic, furosemide (Lasix, Diuride, Frudix, Frusemide) and spironolactone (Aldactone), may be useful, but clinical data on their use and effectiveness is lacking. Carbonic anhydrase inhibitors, such as acetazolamide (Diamox) also serve to decrease the flow of cerebrospinal fluid, but their adverse side effects of abdominal pain, lethargy, and weakness limit long term use.
Surgery to allow the cerebrospinal fluid to flow normally may be necessary to reduce the pain and deterioration. However, such surgeries are technically difficult and should be performed only by specialists. In some cases a shunt is installed. Although surgery often is successful, it is very expensive, and many dogs either have a recurrence of the disease or still show signs of pain and scratching. The most frequent reason for recurrence reportedly is the development of post-operative scar tissue. At least one neurologist has been inserting titanium mesh, in an effort to prevent such scar tissue from building up. More►
Breeders' Responsibilities
SM has a tendency to be more severe in each subsequent generation, and with an earlier onset. Breeders should follow the SM Breeding Protocol. The aim of the breeding protocol is to reduce the incidence of symptomatic syringomyelia in the cavalier breed, and not to create litters of puppies guaranteed not to have SM. The chance of producing an affected dog cannot be predicted without knowing the inheritance.
What You Can Do
4Donate to Rupert's Fund, which pays for MRIs of older dogs, to aid the Syringomyelia Genome Research Project.
4Donate by buying the book, For the love of Ollie.
4Participate in the Syringomyelia Cavalier Collection Scheme. Read about it here.
4Donate funds to cavalier SM DNA research; payee "Syringomyelia DNA Research", address: Stone Lion Veterinary Hospital, Goddard Veterinary Group, 41 High Street Wimbledon Common London SW19 5AU, email CRusbridge@goddardvetgroup.co.uk, telephone: 020 8946 4228, fax: 020 8944 0871. Read about it here.
4Send MRI scans of cavaliers 5 years old or older and which do not have SM, along with MRIs of those dogs' family members, to Dr. Clare Rusbridge at neuro.vet@btinternet.com Read about it here.
4Contact Sheena Stevens in Devon, UK, telephone 01884 821080, email Kilnshena@hotmail.com, about sending aborted cavalier fetuses and deceased young puppies (that have died for any reason) to Dr. Imelda McGonnell at The Royal Veterinary College for research. Read about it here.
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Give to Rupert's Fund! |
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IN DEPTH:
Syringomyelia (SM -- also known as syrinx and hydromyelia, and
occasionally mis-identified as Arnold Chiari malformation) is a condition of
the development of fluid-filled cavities in the spinal cord, which is
believed by researchers to be due to abnormal
flow of cerebrospinal fluid (CSF) between the brain and the spinal cord
through the foramen magnum at the base of the skull.
Technically, hydromyelia is a dilatation of the central canal within the spinal cord, and syringomyelia is the cavitation of the spinal cord parenchyma. Combined, they are referred to either as syringo-hydromyelia (SHM) or hydro-syringomyelia. The disease is referred to generally as syringomyelia and SM herein. This condition is similar, but not identical, to Arnold Chiari Type I Syndrome in humans.
Syringomyelia also may be described as syringomyelia secondary to Chiari-like malformation (CM or CLM). CM is also referred to as occipital hypoplasia (OH) or caudal occipital malformation syndrome (COMS). The full relationship between CM and the development of SM is not fully understood.
SM is rare in most breeds but has become very widespread in cavalier King Charles spaniels. Some researchers estimate that as many as 95% of CKCSs have Chiari-like malformation (CM or CLM), the skull bone malformation believed to be a part of the cause of syringomyelia, and that more than 50% of cavaliers have SM.* It is worldwide in scope and not limited to any country, breeding line, or kennel, and experts report that it is believed to be inherited in the cavalier King Charles spaniel. CM is so widespread in the cavalier that it may be an inherent part of the CKCS's breed standard.
* A 2011 study of 555 UK cavaliers, reported by their owners to be symptom-less, found 25% of one year olds and 70% of 6+ year olds had SM.
The severity and extent of syringomyelia also appear to get worse in each succeeding generation of cavaliers. Other breeds known to be affected to a lesser extent include the Affenpinscher, Bichon Frisé, Boston terrier, Brussels Griffon (Griffon Bruxellois), bull terrier, Chihuahua, French bulldog, Havanese, King Charles spaniel (the English toy spaniel), Maltese terrier, miniature dachshunds, miniature and toy poodles, Papillon, Pomeranian, Pugs, Shih Tzu, Staffordshire bull terrier, and the Yorkshire terrier. See SM in Other Breeds, below, for links to Internet articles about syringomyelia in some of these breeds.
Chiari-like malformation (CM or CLM) -- Occipital hypoplasia (OH) -- Caudal occipital malformation syndrome (COMS)
* Cavaliers have been determined to be brachycephalic. See 2011 report.
-- Chiari-like malformation (CM or CLM)
Chiari-like malformation (CM or CLM) is named after a similar condition in humans, discovered by Dr. Hans Chiari. Chiari-like malformation is defined* as "a condition characterized by a mismatch in size between the brain (too big) and the skull (too small). There is not enough room for the brain and the back part (cerebellum and medulla) is pushed out the foramen magnum." The foramen magnum is a hole in the back of the skull -- the occipital bone -- which leads to the spinal cord. The cavalier appears to have a brain more appropriate for a bigger dog, about the size as that of a Labrador retriever.
* The definition of this term underwent a revision in 2010. Previously to 2010, CM was defined as "decreased caudal fossa volume with caudal descent of the cerebellum, and often the brainstem, into or though the foramen magnum."
CM can be progressive, in the sense that over a period of several months, the length of the cerebellar herniation can increase significantly. However, the severity of CM in a dog does not predict the presence of syringomyelia in that dog. Therefore, other factors are believed to influence the development of a syrinx.
See Karen Kennedy's** Understanding Canine Chiari Malformation and Syrningomyelia for diagrams of the occipital bone and foramen magnum.
** Karen Kennedy, RTMR, MappSc, is a magnetic resonance imaging specialist with The London Health Sciences Centre, London, Ontario, Canada. She prepared these diagrams on behalf of the Health & Education Committee of the CKCSC of Canada.
--- history of Chiari-like malformation research
There is not yet a consensus among veterinary investigators as to how to
measure the cavalier's occipital bone to determine what should be the shape
of the cerebellum within a "normal" CKCS's occipital bone.
Dr.
Clare Rusbridge, BVMS, MRCVS, PhD, DipECVN (right), of the Stone
Lion Veterinary Centre in London, England, a leading investigator into SM,
has described the three "classic features" of Chiari-like malformation as:
(1) loss of the normal round shape of the cerebellum, which can appear to be
indented by the occipital bone; (2) displacement of the cerebellum into and
through the foramen magnum, i.e. herniation; and (3) kinking of the medulla.
2009 and 2010 UK studies in which Dr. Rusbridge later participated
(discussed below) suggest that caudal fossa volume may also play a role in
CM.
In a 2006 study conducted by Dr. Natasha J. Olby and Dr. Sofia Cerda-Gonzalez, both board certified veterinary neurologists, and others at North Carolina State University's College of Veterinary Medicine's Department of Clinical Sciences and the IAMS Pet Imaging Center in Raleigh, NC., they have concluded that the incidence of caudal fossa and cervical spinal abnormalities is high in Cavaliers, and that the pathogenesis of syringomyelia is multi-factorial rather than due to a single malformation.
In a 2009 Scottish study led by Dr. Jacques Penderis, of 70 cavaliers and 80 dogs of other breeds, the researchers found that "all [of the] CKCSs had abnormalities in occipital bone shape. ... CKCSs had a shallower caudal cranial fossa and abnormalities of the occipital bone, compared with those of mesaticephalic dogs. These changes were more severe in CKCSs with syringomyelia."
However, in a January 2009 article, Drs. Sofia Cerda-Gonzalez, Natasha J. Olby, Susan McCullough, Anthony P. Pease, Richard Broadstone, and Jason A. Osborne failed to find the same association when comparing the caudal fossa of CKCS with and without syringomyelia using three-dimensional measurement methods.
Research journal articles published in 2009 and 2010 point to evidence that cavaliers' hind-skull volumes are not different from other small breeds, particularly those with short muzzles, and that the percentage of the volume of the caudal fossa -- the hind-skull cavity -- to the volume of the total cranial cavity, did not differ significantly between those CKCSs with and without SM.
However, these studies also found that the volume of hindbrain within the hind-skull was significantly greater for young -- 2-years and younger -- cavaliers with SM than older dogs -- 5 years and older -- without SM. They also found that increased hindbrain volume in CKCSs with SM, compared to that of the hind-skull, was directly correlated with the size of the dogs' syrinxes.
The first of these investigations was a 2009 German study of 40 cavaliers and 25 dogs of other brachycephalic breeds. The researchers found that: (1) "All CKCSs had cranial characteristics consistent with CLM"; and (2) "There were no significant differences between CKCSs and brachycephalic dogs with respect to the ... volumes of the CF [caudal fossa*] ...". They concluded: "Results of this study suggested that descent of the cerebellum into the foramen magnum and the presence of syringohydromyelia in CKCSs are not necessarily associated with a volume reduction in the CF of the skull."
* The caudal ( for "rear") cranial fossa is part of the cavity within the skull. It contains the brainstem and cerebellum, and towards its rear, it is enclosed by the occipital bone, which also frames the opening called the foramen magnum.
Similarly, in a 2009 UK study comparing the cerebral cranium volumes of the CKCS with those of other small breeds and the Labrador retriever, Hannah Cross and Drs. Rusbridge and Rodolfo Cappello found that cavaliers do not have a proportionately smaller caudal fossa compared to other small breeds, but that the CKCS's brain is comparatively large.
In that 2009 UK study, the researchers stated:
"When compared with Labradors, CKCS had proportionately the same volume of parenchyma [hindbrain] in their caudal fossa [skull], hence there is a mismatch of volumes with too much parenchyma in a too small caudal fossa causing overcrowding. ... Other small breeds of dogs had a proportionately smaller volume of parenchyma in their caudal fossa which can explain why, despite having a similar sized caudal fossa to CKCS, they do not experience overcrowding. It is hypothesised that through the miniaturisation process of other small dogs, both the cranium and brain are proportionately smaller but in CKCS only the cranium has reduced in volume, hence why there is a higher incidence of CM in CKCS than other small breeds.
"Cavalier King Charles spaniels also had a greater percentage of their cranial fossa filled with parenchyma (cranial fossa parenchyma percentage) compared with small breeds and Labradors which had a similar percentage. Overcrowding in CKCS might therefore occur due to a mismatch in volumes in both the caudal fossa and cranial fossa of the skull, suggesting the cranial fossa is also involved in the pathophysiology of CM."
They conclude:
"The results support mesoderm* insufficiency or craniosynostosis** as the pathogenesis of Chiari-like malformation (CM) in CKCS. It presents evidence for overcrowding of the caudal fossa due to a mismatch of brain parenchyma and fossa volumes as to why CKCS and not other small dogs are affected."
*The mesoderm is the middle of the three primary germ cell layers -- the others being ectoderm and endoderm -- in the early stage of an embryo. The mesoderm is responsible for developing various tissues and structures, such as bone, muscle, connective tissue, and the middle layer of the skin. Mesoderm insufficiency during embryology may cause insufficient scope for the mesoderm and ectoderm layers to develop.
**Craniosynostosis is the premature closure of the skull's growth plate.
This suggests both a possible genetic cause of the displacement of the cerebellum through the foramen magnum, as well as evidence that the cavalier's skull may not be too small, but that its hindbrain is too large, hence the "mismatch".
To the contrary, however, in a 2009 Scottish study led by Dr. Jacques Penderis, of 70 cavaliers and 80 dogs of other breeds, the researchers found that "all [of the] CKCSs had abnormalities in occipital bone shape. ... CKCSs had a shallower caudal cranial fossa and abnormalities of the occipital bone, compared with those of mesaticephalic dogs. These changes were more severe in CKCSs with syringomyelia."
In a 2010 UK study report
in the Journal of Small Animal Practice (JSAP),
Colin J. Driver
(right), Dr. Clare Rusbridge, et al.
reiterated findings that
the variations in the dimensions of the cavaliers' posterior
[caudal] cranial
fossa* may not be associated with syringomyelia, since cavaliers do not have
a proportionately smaller caudal cranial fossa compared to other small
breeds. See, also, an abstract of that study
presented before the European College of Veterinary Neurology (ECVN).
*The posterior (or caudal -- for "rear") cranial fossa is part of the cavity within the skull. It contains the brainstem and cerebellum.
The JSAP 2010 study researchers found that a cavalier with a higher volume of hindbrain within the skull is more likely to have SM, and the greater the volume of hindbrain, the larger the syrinx. They also found a direct relationship between between the dimensions of the brain ventricles ("ventriculomegaly" -- see below) and the size of the syrinx.
In addition, the 2010 JSAP research suggested that there may be a "failure of communication" between the paraxial mesoderm* and the cranial somites** with the closing neural tube*** in the embryo, resulting in loss of coordination between the growth of the skull and the hindbrain. When functioning properly, the growth of the mesoderm supports and helps to facilitate the closure process of the neural tube. They concluded that overgrowth of the cerebellum in the embryo may cause the mis-match, because cavaliers have proportionately more hindbrain volume than other small breed dogs. They stated: "Early growth plate closure may result in CM because despite the dynamic nature of osseous tissue, it would be unable to accommodate the developing brain."
*Paraxial mesoderm forms the supraoccipital bone.
**Cranial somitic mesoderm forms the exoccipital and basioccipital bones.
***The neural tube in the embryo develops the brain and spinal cord.
Then, later in 2010, the authors of the 2010 UK JSAP report presented an abstract before the 2010 congress of the British Small Animal Veterinary Association (BSAVA), in which they re-affirmed that, while SM occurs in cavaliers which have CM, it is the mis-match between the volumes of the hindbrain and the hind-skull which is believed to actually lead to SM, if not be the cause of SM. In that abstract, the authors go on to conclude that the more marked volume mis-matches they found between the hindbrain and the skull, the more severe the SM which affected the young dogs -- under 2 years of age -- in the study.
In a December 2010 UK study, led by Colin Driver, the researchers' results were consistent with the previous findings that ventriculomegaly and a small but significant increase in caudal fossa parenchyma are associated with syringomyelia. Further, the December 2010 study also found that the volume of the skulls of CKCS under 2 years of age and SM-affected were significantly smaller than the skull volumes of cavaliers over 5 years of age and SM-clear.
The UK studies in 2009 and 2010 suggest that a disproportionately large hind portion of the brain may be a necessary element of SM in the breed. These 2009 and 2010 research reports explain why CM has been re-defined as "a condition characterized by a mismatch in size between the brain (too big) and the skull (too small). There is not enough room for the brain and the back part (cerebellum and medulla) is pushed out the foramen magnum."
In a June 2011 study, which included Drs. Rusbridge, Driver, and McGonnell, they reported that twelve CM-affected cavaliers' foramen magnums and the length of cerebellar herniation "increased significantly" between MRI scans 9.5 months apart. they concluded:
"This work could suggest that overcrowding of the caudal cranial fossa in conjunction with the movements of cerebrospinal fluid and cerebellar tissue secondary to pulse pressures created during the cardiac cycle causes pressures on the occipital bone. This leads to a resorption of the bone and therefore an increase in caudal cranial fossa and foramen magnum size allowing cerebellar herniation length to increase."
--- most recent findings of Chiari-like malformation research
In an April 2012 study by
Thomas A. Shaw, Imelda M. McGonnell, Colin
J. Driver, Clare Rusbridge, and Holger A. Volk, they
concluded that:
"the CKCS has a relatively larger cerebellum [in purple at right] than small breed dogs and Labradors and there is an association between increased cerebellar volume and SM in CKCS. In contrast to small breed dogs and Labradors, CKCS exhibit correlation between increased cerebellar volume and cerebellar crowding within the caudal CCF, suggesting that CCF growth in CKCS is not keeping pace with the growth of the cerebellum.
"These findings support the hypothesis that it is a multifactorial disease process governed by increased cerebellar volume and failure of the CCF to reach a commensurate size."
They also found:
(a) "CKCS under the age of 2 with SM have an increased cerebellar volume when compared to CKCS over the age of 5 without SM. This supports hypothesis that increased cerebellar volume in CKCS is associated with syringomyelia. Previous volumetric studies in CKCS have shown that there is an association between SM and CCF parenchyma volume, but this is the first time that cerebellar volume has been linked to SM. The cerebellum to brain volume ratio is consistent between normal dogs and has been shown to decrease with cerebellar degenerative disorders, but it has never been shown to be increased in size in a canine neurological disorder."
(b) "The degree of cerebellar crowding in the caudal CCF is correlated with increased volume of the cerebellum in CKCS, and this is not seen in small breed dogs or Labradors."
(c) "The degree of crowding may determine the degree of foramen magnum obstruction, and in turn the tendency for syrinxes to form. Cerebellar volume is potentially a key factor in determining the degree of obstruction and interference in normal CSF flow through the foramen magnum, which disposes dogs to the subsequent development of SM."
(d) "In CKCS an increase in relative cerebellar volume is correlated with an increase in cerebellar crowding in the caudal CCF. It should be noted that small breed dogs and Labradors do not show the same relationship. We infer from this result that during cranial development in Labradors and small breed dogs, a compensatory mechanism maintains the relationship between cerebellar volume and CCF dimensions, and this mechanism is defective in CKCS."
(e) "We also found in CKCS that cerebellar crowding in the caudal CCF is more sensitive to changes in relative cerebellar volume than cerebellar crowding in the rostral CCF, which is consistent with the theory that increased cerebellar volume results in the cerebellum shifting caudally and causes obliteration of dead space in the caudal CCF. This also causes herniation of the cerebellum through the foramen magnum (i.e. CM)."
(f) "In this study, we find that in CKCS, unlike small breed dogs or Labradors, there is a positive correlation between the volume of the cerebellum and degree of crowding in the caudal CCF, which suggests that CM may be due to CCF development not keeping pace with growth of the cerebellum. This supports the idea that CM/SM in CKCS may in fact be multifactorial and an abnormal development process affecting the CCF may be acting as a disease modifier."
(g) "Impaired CCF development may be caused by a failure of communication between one or more of these progenitors and the developing neural tube (specifically, rhombomere 1, which gives rise to the cerebellum). Alternatively, it could simply be explained by premature closure of growth plates between the bones of the CCF."
(h) "It has also been noted on post-mortem examination of CKCS and other small breed dogs that the supraoccipital bone overlying the cerebellar vermis is remarkably thin and sometimes eroded so that the foramen magnum is enlarged dorsally, which could indicate that there has been substantial bone resorbtion. Work is needed to elucidate the mechanisms of occipital growth in dogs to determine the extent to which an osteoresorbtive process can mitigate an enlarged cerebellum in CKCS and in other breeds."
The severity of CM in a dog does not predict the presence of syringomyelia in that dog. Therefore, other factors are believed to influence the development of a syrinx. Ongoing research into genetic correlations between CM and SM seeks to determine whether different genes may control the expression of SM and CM. If so, it may be possible to select breeding stock which has been diagnosed to have CM but may not be expected to produce offspring with SM genes.
-- occipital hypoplasia (OH)
Occipital hypoplasia (OH) has been used to describe the displacement of the cerebellum into the area of the foramen magnum and a kinking of the medulla and an indentation of the cerebellum. "Hypoplasia" is a medical term defined as underdevelopment or incomplete development, and so, "occipital hypoplasia" in this instance means an underdeveloped or incompletely developed occipital bone, which is part of the back of the skull. However, at the November 2006 London conference, this term was rejected because there is no proof yet that the condition is related to a hypoplastic occipital bone. The actual disorder is believed to be caused either by an unusually small occipital bone or a confining membrane within the occipital bone, resulting in the cavity in the skull containing the cerebellum to be too small to fully contain it, leading to overcrowding of the caudal fossa and obstruction of the neural structures, including the incomplete closure or development of the neural tube through which flows the cerebrospinal fluid (CSF).
In a January 2009 article, Drs. Sofia Cerda-Gonzalez, Natasha J. Olby, Susan McCullough, Anthony P. Pease, Richard Broadstone, and Jason A. Osborne concluded that: "While several factors are associated with neurologic signs [of SM], occipital hypoplasia appears to be the most important factor."
Occipital hypoplasia is to be distinguished from occipital dysplasia, which is an incomplete ossification of the supraoccipital bone, causing a widening of the foramen magnum. The more brachycephalic is the shape of the dog's skull, the more likely there will be occipital dysplasia. The cavalier is a brachycephalic breed, and therefore a combination of both occipital hypoplasia and occipital dysplasia can occur in the CKCS.
In a 2008 German study, the researchers recommend that cavaliers be screened for both occipital hypoplasia and occipital dysplasia.
-- caudal occipital malformation syndrome (COMS)
Caudal occipital malformation syndrome (COMS) had been used, particularly by some specialists in the United States, to describe the disorder. However, at the November 2006 London conference, the term COMS also was rejected because there is no proof yet that the condition is related to a malformed occipital bone. Nevertheless, some diehard neurologists in the northeast USA persist in using this term when referring to Chiari-like malformation in cavaliers.
Because prior to the November 2006 London conference, CM and OH and COMS all were used to describe the same malformation, they all are used interchangeably in this article. See Karen Kennedy's* Understanding Canine Chiari Malformation and Syrningomyelia for scans of the occipital bone and foramen magnum, comparing "normal", mild Chiari" and "severe Chiari" dogs.
* Karen Kennedy, RTMR, MappSc, is a magnetic resonance imaging specialist with The London Health Sciences Centre, London, Ontario, Canada. She prepared these diagrams on behalf of the Health & Education Committee of the CKCSC of Canada.
-- pain due to CM
Dogs with CM but not syringomyelia (SM) can experience discomfort, including pain. This is attributed to a direct compression of the medulla oblongata, which is involved in the modulation of pain.
What SM is
Syringomyelia (SM) is defined as "a condition that results in the development of fluid-containing cavities within the parenchyma of the spinal cord. as a consequence of abnormal cerebrospinal fluid movement." (November 2006 International Conference on Syringomyelia).
Cerebrospinal fluid normally flows back and forth between the brain and spinal cord with each heart beat. As the heart pumps blood to the brain, the CSF flows from the brain through the hole called the foramen magnum to the spinal cord, to accommodate the increased volume of incoming blood.
Syringomyelia is believed to result when the cerebrospinal fluid is prevented from circulating normally between the brain and spinal cord, due to a narrowing or blockage of the CSF flow at the foramen magnum, thereby forcing the CSF at a higher than normal pressure into the spinal cord. The pressure difference causes the spinal cord to distend or pull apart, creating a cavity called a syrinx, and squeezing fluid from blood vessels and other tissues into the cavity.
Syringomyelia is an extremely serious, progressively worsening spinal disease which is rare in most breeds but is becoming very widespread in cavalier King Charles spaniels of all bloodlines. In May 2005, Dr. Rusbridge and Susan P. (Penny) Knowler, BSc (Hons), who have been studying the disease in several hundreds of cavaliers, reported that a conservative estimate is that at least 50% of cavalier King Charles spaniels have a degree of Chiari-like malformation, although not all are so severely affected as to have syringomyelia. In February 2010, Dr. Georgina Child, board certified veterinary neurologist in Australia, reported that of 60 asymptomatic cavaliers scanned as potential breeding stock, 50% had SM syrinxes. In a September 2010 report of 804 cavaliers, Mrs. Knowler and others estimated that "the lifetime risk of developing syringomyelia in the study population was estimated to be 55%."
In a 2011 study of 49 cavaliers diagnosed with SM, Dr. Rusbridge and others found that "total syrinx size was positively correlated with age" of the dogs. In a June 2011 study of 555 cavaliers without any symptoms of syringomyelia, 25% of the one year old dogs had SM and 70% of the dogs aged 6 years and older had SM.
-- role of the ventricle system (vetricular dilatation - ventriculomegaly)
The brain's ventricle system consists of
four cavities which are connected with the spinal cord's central canal. The
four ventricles are known as the two lateral ventricles, the third
ventricle, and the fourth ventricle. The ventricles are the source of CSF
and are the brain's respository of CSF.
Some neurologists are including in their examination reports an analysis of whether the ventricles are dilated, and if so, a measurement of the amount of their dilatation. The medical term for dilated lateral ventricles is ventriculomegaly. In a December 2010 UK study, also led by Colin Driver, the researchers' results were consistent with the previous findings that ventriculomegaly and a small but significant increase in caudal fossa parenchyma are associated with syringomyelia.
-- other causes of SM
There are other forms of syringomyelia in canines. Spinal dysraphism or spinal dysplasia is a genetic disorder in which puppies normally under the age of three months display a bunny hopping gait and wide-based stance and scoliosis, due to the spinal cord not developing completely in the womb. Dalmatians, English setters, golden retrievers, rottweilers, visla, and Weimaraners have been identified with this disorder. Also, SM may be caused by tumors, cysts, or trauma. Neither of those are discussed here.
Symptoms
Symptoms may vary widely among different dogs, but the earliest sign
often is that the dog feels a sensitivity in its neck area, causing in some an
uncontrollable urge to scratch at its neck and shoulders excessively,
particularly when walking or during other forms of exercise. This is
due to an increase in the pressure of the flow of cerebrospinal fluid
through the central canal from the brain down the spinal column, causing the
central canal to expand and press against the nerves of the spinal column
and creating the needle-like tingling which prompts the dog to scratch.
Click here
or the YouTube logo to see videos of cavaliers with SM symptoms.
Many symptoms of SM, such as scratching, are so ordinary (when not excessive or compulsive) that they could be attributed to any of several common causes, including flea bites or allergies.
SM and CM very seldom can be detected in young puppies, as symptoms usually are not evident before the age of six months or even many years later. There is no way to know in advance of the symptoms whether a dog is normal or is a syringomyelia carrier which does not develop the disease but can pass it on to its offspring.
The condition causes damage to the spinal cord and usually results in symptoms of hypersensitivity, intense pain, and leg dysfunction. The primary symptoms may vary widely, and in some cases, a cavalier may even have SM without displaying any outward symptoms at all. Some cavaliers diagnosed with SM lack any clinical signs. It also is possible that a dog with Chiari-like malformation (CM) does not have syringomyelia (the syrinx in the spinal cord), but still may have symptoms of SM due to the CM obstructing the flow of cerebrospinal fluid (CSF). This also is attributed to a direct compression of the medulla oblongata, which is involved in the modulation of pain.
An excellent review of the various symptoms displayed by dogs affected with syringomyelia may be found on the SM.CavalierTalk.com website, prepared by Karlin Lillington of Dublin, Ireland. Her website includes videos of SM-affected dogs. Other videos are available under Related Links below.
-- expressions of pain
As the disorder progresses, there usually follows increasingly severe pain around the dog's head, neck, and shoulders, causing it yelp or scream. It is believed to be a neuropathic pain, probably due to disordered neural processing in the damaged dorsal horn. As the disease destroys portions of the cavalier's spinal cord, the dog may experience so much pain that it may contort its neck and may even sleep and eat only with its head held high. Ultimately, the dog may develop scoliosis, as a result. There may also be progressive weakness in the legs, so that walking becomes increasingly difficult. Some dogs deteriorate to the point of paralysis.
In a June 2007 study of 55 cavaliers, the researchers reported that the wider the syrinx, the stronger the predictor of pain, scratching behavior and scoliosis in dogs with syringomyelia. They stated: "Both pain and syrinx size were positively correlated with syrinxes located in the dorsal half of the spinal cord." They also concluded that such pain is likely to be neuropathic pain, resulting from disordered neural processing in the damaged dorsal horn.
Syringomyelia can be very deceptive because some symptoms (which may include paw licking, head shaking, head rubbing, circular walking, fly biting, and reluctance to defecate) are common behaviors for many unaffected dogs. One distinction is that dogs suffering from SM engage in these patterns excessively and seemingly compulsively. So, other causes of the dog's symptoms need to be considered and should be ruled out before concluding that SM is the cause. For example, if a syrinx develops in a lower area of the spine, such as the lumbar region, the dog may scoot excessively, even to the extent of rubbing the anal area raw. However, scooting is a common symptom of other disorders, or even of no particular disorder at all.
In a 2009 study of 64 cavaliers affected with CM/SM, Drs. Sofia Cerda-Gonzalez, Natasha J. Olby and others classified clinical signs of pain from grade 0 to grade 5, by which the dogs displayed symptoms of neck scratching, head scratching, neck pain upon neurolgoical examination, as well as ataxia and paresis detected upon examination. See table below:
In a 2010 Canadian study, researchers found a significant linear correlation between the severity of neurologic dysfunction and size of the syrinx, with a larger syrinx being associated with more severe neurologic signs.
In an April 2012 study, Geoffrey Skerritt and Dr. Luca Motta observed that the level of neurological pain a dog experiences can only be based upon subjective evaluations of the dog's behaviors, which includes the dog's owner's subjective observations.
In order to evaluate changes in the level of a dog's discomfort as objectively as possible, to determine whether their surgical procedure on the dog was successful (see "syringosubarachnoid shunt" below) these neurosurgeons devised a Pain Score Scheme (see table below) for the dog's owners to measure pain which the dog experiences from CM and SM, particularly following surgery. Their pain score scheme was created on the basis of different neurological grade classifications previously suggested by other researchers, including the Cerda-Gonzalez / Olby 2009 study above. Mr. Skerritt and Dr. Motta evaluated their patients’ histories and found some specific information that could be used to create an objective pain score (i.e., frequency of scratching episodes and site of scratching, screaming episodes). However, because of the inherent subjectivity of relying upon reports from the dog's owners, they concluded that the design of a more robust scoring system together with prospective studies was warranted.
-- other disorders with similar symptoms
Another disorder common to cavaliers and with symptoms similar to SM is Primary Secretory Otitis Media (PSOM), which is a highly viscous mucus plug which fills the middle ear and causes the tympanic membrane to bulge. Because the pain and other sensations in the head and neck areas, resulting from PSOM, are so similar to symptoms due to SM, the possibility that the cavalier has PSOM and not SM should be determined before diagnosing SM.
In a brief July 2009 article, UK researchers Dr. Richard J Piercy and Gemma Walmsley disclosed that they had identified a genetic form of muscular dystrophy in the cavalier, with symptoms (weakness and exercise intolerance) similar to some of those of SM. However, these other symptoms of this muscular dystrophy may clearly distinguish it from SM: muscle atrophy, difficulty swallowing, and an enlarged tongue. Also, the researchers have found that only males are affected by this form of muscular dystrophy, and the females are only carriers of the mutation.
Also, see
flycatcher's syndrome for a description of another disorder prevalent in
CKCSs and which has identical symptoms to the fly biting of some
SM/CM-affected dogs.
Dr. Curtis Dewey has reported that in the course of his examination of MRIs of cavaliers with Chiari-like malformation, he also has discovered cerebellar infarcts (strokes). He has written that CKCSs appear to be pre-disposed to infarcts due to the presence of CM and that the existence of both CM and infarcts "is common in the CKCS." See Cerebellar Infarcts for details.
Dr. Rusbridge has a website, veterinary-neurologist.co.uk, which discusses SM extensively, as well as other neurological disorders which she has researched. Her doctoral thesis, a 200+ page book (right), Chiari-like Malformation and Syringomyelia in the Cavalier King Charles Spaniel, also is available online.
Diagnosis
-- magnetic resonance imaging (MRI)
The only accurate way of diagnosing the disease is through the use of magnetic resonance imaging (MRI) scanning. Clinic charges for MRI examinations of canines have been known to vary from $400.00 to over $2,000.00. Accurate MRI results require that usually the dog be anesthetized. In view of the high cost of MRI scans, the examining veterinary specialist usually will attempt to rule out other causes of the symptoms first. Veterinarians who perform MRIs of should consider following this MRI Screening Protocol devised by Dr. Rusbridge.
The MRI allows the veterinary neurologist or neurosurgeon to study the
skull and spine for the presence of any abnormality which might
obstruct the flow of the cerebrospinal fluid. When examined by MRI,
the syringomyelia appears as a tubular cavity of fluid, called a syrinx,
within the spinal cord. In severe cases, the syrinx is so wide that only a
thin rim of the spinal cord is visible. An MRI scan of a dog without
any syrinxes at all still may show that the dog has Chiari-like
malformation.
The MRI scan of a cavalier at the right shows the occipital malformation, with the cerebellum being squeezed out of the occipital bone and into the area of the foramen magnum (red-outlined area). It also shows pockets of white cerebrospinal fluid in the spinal cord (yellow-outlined area). See Karen Kennedy's Basic Canine NeuroAnatomy and MRI Imaging Planes, for further information about MRI scans.
In a study conducted by Dr. Rusbridge and Ms. Knowler, in a sample of seventy "unaffected" cavaliers from Europe and North America, which were MRI-scanned only for breeding purposes, 70% of them had syringomyelia, 17% were "at risk", meaning were young dogs with Chiari-like malformation but no syringomyelia yet, and only 13% were "clear" of both the malformation and SM. In February 2010, Dr. Georgina Child, board certified veterinary neurologist in Australia, reported that of 60 asymptomatic cavaliers scanned as potential breeding stock, 50% had SM syrinxes.
In MRI studies of 49 cavaliers, reported in 2011 in the Veterinary Journal, Dr. Rusbridge and others found that "Syrinx formation was present in the C1–C4 region and in other parts of the spinal cord. The maximal dorsoventral syrinx size can occur in any region of the spinal cord." Seventy-six per cent of CKCS with a a cranial cervical syrinx also had a syrinx in more caudal spinal cord regions. Therefore, so-called "mini-MRI-scans" of only the cervical region, such as those scans for breeding protocol purposes, may not necessarily locate all syrinx which an SM-affected cavalier may have.
Dr. Curtis Dewey has reported that in the course of his examination of MRIs of cavaliers with Chiari-like malformation, he also has discovered cerebellar infarcts (strokes). He has written that CKCSs appear to be pre-disposed to infarcts due to the presence of CM and that the existence of both CM and infarcts "is common in the CKCS." See Cerebellar Infarcts for details.
-- computed tomography (CT)
Computed tomography (CT) is an imaging method using digital geometry processing to generate a three-dimensional image of the inside of an object from a large series of two-dimensional x-ray images taken around a single axis of rotation. Researchers have been studying the value of CT scans to detect Chiari-like malformations and syrinxes in cavaliers and comparing the results with MRIs and other resources. In a very preliminary 2008 French study, researchers CT scanned sixteen CKCS to measure the size of their caudal fossas and to determine standard computed tomography dimensions of the caudal fossa.
Dr. Dominic J. Marino of Long Island Veterinary Specialists (LIVS) reported in October 2007 that evaluation of the entire skull shape and size utilizing Spiral CT technology with 3D reconstruction is currently underway to identify additional mechanisms of syrinx formation. He wrote that CT scanning may enable surgeons to focus on correcting the flow of CSF as the malformation affects its normal passage around the brain and spinal cord and leads to the syrinx formation known as syringomyelia.
-- thermography (medical infrared imaging -- MII)
Medical infrared imaging (MII), also called thermography, is a non-invasive imaging technique which records thermal patterns. It provides information about the function of the sympathetic nervous system. Thermal imaging has drawn the interest of veterinary researchers as a potential screening test for CM in dogs due to its ability to image dogs without sedation. In a preliminary 2007 study at Long Island Veterinary Specialists (LIVS), Dr. Dominic J. Marino's team found that cavaliers with CM had “cooler” thermographic patterns when compared with a dog with a normal caudal fossa. Dr. Marino reported in October 2007 that, "based on these very preliminary findings, thermography may be a viable imaging modality to use as a screening tool to detect CLM in dogs."
In a June 2011 study of 105 cavalier King Charles spaniels, Drs. Marino and Catherine Loughin found that MII was up to 97.3% accurate in identifying dogs with CLM. They concluded, "Based on these preliminary findings, MII may be a viable screening tool to detect CLM in dogs."
-- ultrasound
In 2005, Drs. Dominik Faissler and John (Jay) McDonnell, board certified veterinary neurologists at the Cummings School of Veterinary Medicine at Tufts University in Massachusetts, researched the use of ultrasonography to diagnose syringohydromyelia in dogs. In a 2005 interim report, they stated, "This preliminary study indicates that cervical spinal cord ultrasound can be useful as a diagnostic aid for CM. It cannot rule out a diagnosis of CM, however no false positives were found. To investigate the sensitivity and specificity of this imaging modality blinded U/S examination of large numbers of dogs after MRI evaluation is planned."
In the same 2008 French study reported under computed tomography above, one dog's syrinx was identified by ultrasound. The researchers found that ultrasonography probably has too low a sensitivity for reliable diagnosis of Chiari-like malformation/syringomyelia.
In an August 2008 report by German researchers using ultrasound as a comparative imaging technique to MRIs, they compared 10 normal brachycephalic dogs with 25 cavaliers known to have Chiari-like malformation. They found that "Cerebellar displacement into the foramen magnum was clearly identified sonographically; however, syringohydromyelia was not discernable due to bone overlay."
-- brainstem auditory evoked response (BAER)
A supplemental diagnostic screening tool used by at least two veterinary neurologists, Dr. Curtis W. Dewey and Dr. Georgina Barone, and by Dr. Dominic J. Marino is the BAER (for Brainstem Auditory Evoked Response) test. The BAER test measures the timing of electrical waves from the brainstem in response to clicks in the ear. Dr. Dewey reported that, assuming the dog is not deaf, the detected brain waves can be used to assess the integrity of the brain stem, since CM involves some degree of brain stem compression.
As of October 2007, Dr. Marino reported that "38 Cavalier King Charles Spaniels had been evaluated thus far. One dog had a normal MRI, BAER, and thermographic evaluation. Twenty-three dogs without clinical signs had abnormal MRI findings with 16 of the 23 dogs (69.6%) also having abnormalities with BAER testing. Fourteen dogs with clinical signs had abnormal MRI findings and 13 of the 14 dogs (92.8%) also had abnormal BAER tests. BAER testing may play a more useful role in screening 'clinical' dogs rather than dogs without clinical signs.
In a 2010 report, a group of Canadian neurologists tested fifty cavaliers to evaluate the validity of BAER as well as transcranial magnetic motor evoked potentials (TMMEP), somatosensory evoked potentials (SSEP), and spinal evoked potentials (SEP), compared to MRIs. The researchers found: "TMMEP, SSEP, SEP and BAER do not appear to be valuable tests in detecting functional abnormalities of the motor and sensory pathways throughout the central nervous system of CKCS dogs with and without neurological signs secondary to SM diagnosed by MRI."
The following MRI photographs, and their descriptive text, are courtesy of Dr. Clare Rusbridge and Ms. Penny Knowler of Stone Lion Veterinary Centre:
Left: This image shows mild Chiari-like malformation – the cerebellum is very slightly indented, the kinking of the medulla is normal for a toy breed and there is displacement of the cerebellum into and just out of the foramen magnum. The ventricular system is slightly dilated.
Right: Although the cerebellum is not coming through the foramen magnum,
this dog has a greater degree of Chiari-like malformation than the first
dog. The cerebellum is indented, and the medulla is kinked. The central
canal is dilated above the first disc space – this is the first sign of
syringomyelia developing. There is also mild ventricular dilatation.
Left: This dog has descent of the cerebellum towards the foramen magnum and the
cerebellum is indented. The medulla is normal for a toy breed; there is mild
ventricular dilatation and a small syrinx/central canal dilatation in the
upper cervical spinal cord.
For more MRI views of cavaliers with syringomyelia or the Chiari-like malformation, see Karen Kennedy's* Understanding Canine Chiari Malformation and Syrningomyelia and Related Links below.
*Karen Kennedy, RTMR, MappSc, is a magnetic resonance imaging specialist with The London Health Sciences Centre, London, Ontario, Canada.
Reduced Rate MRI Clinics
in United States and Canada
The names and locations of veterinary neurologists who are board certified by the American College of Veterinary Internal Medicine (ACVIM) are on our Neurologists webpage. Some MRI clinics which are offering reduced rates for partial scans of cavaliers are listed below. Be aware that prices for MRI scans at these clinics are subject to change and may not include other services which are necessary for a complete analysis of the dog's condition. Veterinarians who perform MRIs are advised to follow the MRI Screening Protocol.
4LOS ANGELES, CA: Through January 2012, Dr. Sheila Carrera-Justiz, board certified veterinary neurologist, offers mini-scans for $750.00, which include the consultation, anesthesia, a copy of the MRI on CD and interpretation. The scan is from the inter-thalamic adhesion to C5 or lower. It also covers axials of the tympanic bullae to evaluate for PSOM. Blood work no older than one month is required and can be performed at the clinic. Contact Dr. Carrera-Justiz at VCA-West Los Angeles, at 1818 S. Sepulveda Blvd., Los Angeles, CA, 90025, Tel: 310-473-2951, Email: sheila.carrera-justiz@vcahospitals.com, website: www.vcawla.com
4LOS ANGELES, CA: Beginning in February 2012, Dr. Veronique Sammut, board certified veterinary neurologist, offers mini-scans for $750.00, which include the anesthesia, a copy of the MRI on CD and interpretation. The scan is from the inter-thalamic adhesion to C5 or lower. It also covers axials of the tympanic bullae to evaluate for PSOM ("glue ear"). Recent blood work (no older than one month) is required or can be performed at the hospital. Contact Dr. Sammut at VCA-West Los Angeles, at 1818 S. Sepulveda Blvd., Los Angeles, CA, 90025, Tel: 310-473-2951, Email: veronique.sammut@vcahospitals.com, website: www.vcawla.com
4REDWOOD CITY, CA: AnimalScan at 410 Brewster Avenue, Redwood City, CA 94063, telephone 650-480-2001, email info@animalscan.org See Easton, PA entry for details.
4GAINESVILLE, FL: Dr. Thomas A. Schubert, board certified veterinary neurologist and Chief of Neurology Service at the University of Florida's College of Veterinary Medicine, offers cavaliers an MRI Package for $650 to $750 per dog. This includes a full physical and neurological exam, general anesthesia and recovery, the MRI, consultation about the findings from the MRI, and a copy of the MRI to take home. Owners that would like to bring more than 3 dogs may be eligible for a discount on the exam fee. However, this must be discussed before you come for your appointment or you will not be given a discount. If your CKCS, has a history consistent with possible PSOM and the MRI confirms this diagnosis, then treatment can be performed during anesthesia for this MRI with the school's Dermatology Service for the additional cost of $350 to $500. This option must be discussed and arranged prior to appointment day. The conditions for this low fee are: (a) the owner brings a current blood test report (no more than two weeks old); and (b) there are no complicating health issues, such as heart problems. Contact Dr. Schubert's technician, Amy Reynolds, email Reynoldsa@ufl.edu
4NAPLES, FL: Dr. Michelle Carnes, board certified veterinary neurologist at Animal Specialty Hospital of Florida, offers an MRI package for asymptomatic (non-clinical) patients at $900.00 (for three or more dogs), $1,000.00 (for two dogs), and $1,100.00 for one dog. The MRI scan is a mini-scan from interthalamic adhesion to C5. The price includes a neurologic exam/physical prior to the scan and a consultation following the scan for review of study, anesthesia, a written interpretation of the scan, and a copy of the MRI on a CD. Bloodwork is required and is not included in the price. Bloodwork should be no older than two weeks. A report from a board certified veterinary radiologist can be obtained for an additional fee. For more information, contact Eric Carnes, telephone 239-263-0480, email ecarnes@ashfl.com. Animal Specialty Hospital of Florida is located at 10130 Market Street, Suite 1, Naples, Florida 34112, telephone: 239-263-0480, fax: 239-263-0488, website: www.ashfl.com
4FORT WAYNE, IN: Advanced Animal Imaging offers Cavalier breeders a $495.00 mini-scan MRI per dog, which includes a consultation, reading of the scan, and anesthesia. Pre-screening bloodwork is required prior to anesthesia and is available for $75.00 at the Indian Creek Veterinary Hospital in the same building. The clinic follows Dr. Rusbridge's SM MRI screening protocol. Contact the clinic at telephone 260-434-1555 to make appointments. Advanced Animal Imaging is located at 5902 Homestead Road, Fort Wayne, IN 46814, and its website is www.advancedanimalimaging.com
4AMES, IA: The Lloyd Veterinary Medical Center at the University of Iowa offers a mini-scan MRI package at approximately $800.00, consisting of an examination, MRI scan, and anesthesia. To schedule an appointment, call the neurology service at 515-294-4900. It is located at 1600 S. 16th Street, Ames IA 50011, and its website is vetmed.iastate.edu/vmc
4OVERLAND PARK, KS: Dr. Brian C. Cellio, board certified veterinary neurologist at Veterinary Specialty and Emergency Center in Overland Park, Kansas (near Kansas City) offers Cavalier breeders a $900.00 mini-scan MRI per dog for a minimum of five dogs up to ten dogs per day. Contact Dr. Cellio's technician, Mandi, telephone 913-642-9563 or 800-413-6851 to make appointments. The clinic is located at 11950 West 110th Street, Suite B, Overland Park, KS 66210, and its website is www.vseckc.com
4COMMERCE, MI: Drs. Michael Wolf, Jared B. Galle, and Andrew Isaacs, board certified veterinary neurologists at Animal Neurology & MRI Center in Commerce, Michigan, offer Cavalier breeders reduced rates as low as $975.00 for an MRI scan. Rate includes a neurological examination, anesthesia, MRI scan and consultation/review of the MRI study with the neurologists, for a minimum of three dogs. Review and MRI imaging report from their board certified radiologist can be requested for an additional fee. Contact Dr. Wolf at the Animal Neurology & MRI Center, 1120 Welch Road., Commerce, MI 48390, Tel: 248-960-7200, email DrWolf@animalneurology.com, website www.animalneurology.com
4COLUMBIA, MO: University of Missouri's College of Veterinary Medicine (Drs. Joan R. Coats, Dennis P. O'Brien, and Fred A. Wininger) offers CM/SM scans for $500.00, which includes "iso" anaesthesia. Blood work is additional and may be obtained ahead of time at your veterinarian's office. Contact Stephanie Gilliam, Neurology/Neurosurgery Technician, University of Missouri Veterinary Medical Teaching Hospital, 900 E. Campus Drive, Columbia, MO 65211, telephone 573-882-7821.
4ITHACA, NY: Cornell University's College of Veterinary Medicine's Department of Clinical Sciences, in Ithaca New York, is offering low cost MRIs (as low as $650.00 each). Contact Dr. Curtis W. Dewey, board certified veterinary neurologist and board certified veterinary surgeon, telephone 607‑253-4445, email cwd27@cornell.edu See more about Dr. Dewey under Current Research below.
4PLAINVIEW, NY: Long Island Veterinary Specialists (LIVS) in Plainview, New York offers low cost MRIs and other procedures, including BAER, thermography evaluation, and a neurology consultation. LIVS has plans to add spiral CT to the evaluation soon. The program is open to all dogs, but the lowest rates -- as low as $500.00 -- are for dogs in groups of three or more. Contact Dr. Dominic J. Marino, board certified veterinary surgeon and chief of staff, telephone 516-501-1700 (ask for Alexis or Lexi), email Bongorno@aol.com, webpage www.livs.org. Dr. Marino advises that LIVS averages 20 MRIs per week and has operated on an average of one dog diagnosed with COMS per week for the past several years. See more about Dr. Marino under Current Research below.
4RALEIGH, NC: AnimalScan, at North Carolina State University's College of Veterinary Medicine's Department of Clinical Sciences, 4700 Hillsborough Street, Building 3, Raleigh, NC 27606, telephone 919-838-5209, email raleigh@animalscan.org See Easton, PA entry below for details.
4AKRON, OH: Pets Dx Veterinary Imaging, Inc. in Akron, Ohio and Pittsburgh, Pennsylvania, offers a partial MRI, at reduced group rates for Cavaliers, focusing on the head and neck, and includes a compact disc with an imaging program. Their MRIs may be reviewed, for an additional fee, by Dr. Patrick R. Gavin, Diplomate ACVR, Professor of Radiology, Washington State University College of Veterinary Medicine, in consultation with the dog's veterinarian. Pets Dx Veterinary Imaging, Inc. is located at 1321 Centerview Circle, Akron, Ohio 44321, telephone 330-576-6275, and at 807 Camp Horne Road, Pittsburgh, PA 15237, telephone 412-486-4800 and 412-348-2577. Its website is www.petsdx.com
4MISSISSAUGA, ON: Matheson Boulevard Veterinary Services in Mississauga, Ontario offers reduced cost MRIs for Cavalier breeders, through the efforts of the CKCS Club of Canada. See details and current prices on the club's website CavalierCanada.com Participants will receive a full neurological exam by a Veterinarian. They will also receive a full MRI that meets all current scanning protocols, a CD copy of their MRI screening, and a grading certificate issued by Dr. Clare Rusbridge. See the clinic's website mbvs.ca for information about required border-crossing documentation.
4EASTON, PA: AnimalScan offers mini-MRI scans for $500.00, following the proposed new SM MRI-scanning protocol. This offer is to Cavalier breeders for screening purposes. AnimalScan has a board certified radiologist, Dr. Alexia McKnight, but does not have a neurologist on staff and does not provide medical care. If a dog is symptomatic, the fee for a full diagnostic scan to determine the extent of disease would be from $1425 to $1950. AnimalScan is located at 2026 Lehigh Street, Easton, PA 18042. Contact: Medical Director Dr. Meg Alonso, telephone 877-838-6747, email DrAlonso@AnimalScan.org, website www.AnimalScan.org
4PITTSBURGH, PA: Pets Dx Veterinary Imaging, Inc., 807 Camp Horne Road, Pittsburgh, PA 15237, telephone 412-486-4800 and 412-348-2577. See Akron, Ohio entry above for details.
4MT PLEASANT, SC: Dr. Peter J. Brofman, (ACVIM Neurology & Internal Medicine) and Veterinary Specialty Care offer a reduced rate for MRIs for breeding screening protocols only. The fee of $1000 includes the MRI and anesthesia but pre-anesthetic blood work is not included. The MRI unit is a 1.5T magnet and is available for screenings Monday through Friday. Veterinary Specialty Care is located at 930 Pine Hollow Rd, Mt. Pleasant, SC 29464. You may contact Dr. Brofman at 843-884-2441, peterbrofman@gmail.com , or www.facebook.com/drpeterbrofman
4LEESBURG, VA:
Bush Advanced Veterinary Imaging,165 Fort Evans Road, Leesburg, VA 20176,
telephone 703-669-5544, website
www.bvns.net. Bush
Veterinary Neurology Service (BVNS) has provided this additional
information: "We offer Cavalier breeders MRI screening studies at a
discounted rate for non-clinical patients. Clinical patients must be
evaluated by a boarded neurologist first and would then receive a full study
rather than the discounted screening study. Owners can contact Bush
Veterinary Neurology Service to schedule appointments for clinically
affected patients at 703-669-2829. For multiple non-clinical patients, we
perform studies on Sundays once a month. The cost for the first patient is
$595.00 and subsequent patients are $575.00. We can accommodate 5
non-clinical patients on a Sunday. For single patients, we perform the
screening studies on weekdays at 8 am at a cost of $695.00. Owners will
receive a copy of the images on CD, an interpretation of the results from
one of our boarded neurologists, as well as instructions on how to contact
Dr. Rusbridge for additional information.
"Your pet will need to have minimum blood work performed by your
veterinarian within 7 days of the MRI screening at Bush Advanced Veterinary
Imaging. Please bring a copy of the blood work with you at the time of your
MRI screening appointment. The blood work should have, at minimum, a pack
cell volume (PCV), total protein (TP), blood urea nitrogen (BUN/Azostick),
and a blood glucose (BG) level." Additional information can be obtained
here. Board certified neurologists on staff are Drs.
William Bush, Joli
Jarboe, and Deena
Tiches.
4VIENNA, VA: AnimalScan at 328 Maple Avenue East, Vienna, VA 22180, telephone 703-281-9440, email vienna@animalscan.org See Easton, PA entry for details.
4UNITED KINGDOM: See the list of MRI clinics on the website of The Cavalier King Charles Spaniel Club at www.thecavalierclub.co.uk/health/syringo/mriscan.html
NOTE: If you know of other MRI clinics offering reduced rate scans or mini-scans for SM or CM, please let us know by emailing us at Editor@CavalierHealth.org
DNA Testing
Dr. Rusbridge
reported in May 2010 that genetic
researchers Quoc-Huy Trinh, Penny Knowler,
Alexandra
Thibault,
Marie-Pierre Dubé, Guy A. Rouleau, Clare Rusbridge, and Zoha Kibar may have found the site for SM on the cavalier's genome.
In a May 20, 2010 update on her website,
Dr. Rusbridge publishes an interim report in highly technical wording, which
states that they have located a haplotype which contains mutations in
SM-affected dogs and does not contain such mutations in unaffected
cavaliers. Gene sequencing and additional mapping of the locus are under way.
A team of Montreal researchers, including LeMay P, Trinh QH, Dubé MP, Rusbridge C, Rouleau GA, and Kibar Z, reported in June 2011 that they had identified a chromosome 2 region associated with Chiari-like malformation in the Brussels Griffon breed. See summary here.
Progression
SM is a progressive disease*, but its progression can be is extremely variable. Some cavaliers initially may exhibit no scratching or pain; others tend to scratch with only mild pain and no other neurological signs. For some dogs, the initial mild symptoms may never worsen. Other CKCSs can be severely disabled by pain and neurological signs within twelve months of the first signs developing.
* Chiari-like malformation (CM) also has been found to be progressive in some cavaliers.
Dr. Rusbridge stated in 2010, "In our experience, many cases of syringomyelia are not progressive, especially if the syrinx is small." In a 2011 study of 49 cavaliers, the UK researchers found that "the severity of SM was positively correlated with patient age. This is consistent with previous studies indicating that CKCS with SM were significantly older than dogs without SM (Couturier et al., 2008). It seems likely therefore, that SM is a progressive disease in dogs."
Clinical statistics show that about 45% of affected cavaliers develop signs of SM before their first birthday; another 40% will show symptoms between ages one and four years; the 15% balance develop signs later, with the oldest reported case of first developing symptoms at nearly seven years of age.
In a June 2011 study of 555 cavaliers without any symptoms of syringomyelia, 25% of the one year old dogs had SM and 70% of the dogs aged 6 years and older had SM.
Treatment
The primary goal of treatment is to obtain relief from pain. Treatment options consist of drugs and surgery, as are examined in detail below. Dr. Rusbridge has prepared a diagram of treatment options, which she calls a treatment algorithm, which is downloadable here in pdf format.
Dr. Rusbridge stated in 2010:
"In our experience, many cases of syringomyelia are not progressive, especially if the syrinx is small, i.e. not every case with this disease needs be managed surgically and many do well on medical management, with drugs that reduce cerebrospinal fluid pressure (e.g. antacids such as cimetidine and omeprazole), non-steroidal anti-inflammatory drugs and adjuvant analgesics such as gabapentin (see Drugs, below). When the surgery for this disease has questionable long-term success it may be more appropriate to treat mild cases medically. As a rule I rarely use corticosteroids when treating spinal cord disease."
-- drugs
Treatment options for CM/SM are very limited. Before the disease progresses to its severe form, the use of anti-inflammatory cortisteroids, such as prednisolone (Prelone), methylprednisolone (Medrol, Medrone), and dexamethasone (Decadron, Dexamethasone Intensol, Dexone, Hexadrol), or non-steroidal anti-inflammatory drugs (NSAIDs), such as carprofen (Rimadyl), meloxicam (Metacam), firocoxib (Previcox), mavacoxib (Trocoxil), and aspirin, may relieve the symptoms but not the deterioration.
NOTE: Dogs should never be treated with both a cortisteroid and an NSAID at the same time.
It has been reported that SM-affected cavaliers have been found to have a high level of inflammatory proteins in their bodies, and that for that reason, NSAIDs often provide some initial relief from pain. Also, doxycycline, a tetracycline antibiotic designed to treat bacterial infections, has been prescribed to CM/SM patients as an anti-inflammatory similar to NSAIDs.
Cortisteroids have serious side effects, such as weight, gait, and skin changes, and harmful suppression of the immune system. Long term use of these drugs is not advised.
NSAIDs and other conventional analgesic medications have not been found to be effective by themselves to relieve pain. Two 2007 studies (1) (2) show that the type of pain behavior suggests that the dogs experience neuropathic pain, probably due to disordered neural processing in the damaged dorsal horn, and that, "as such it is likely that conventional analgesic medication may be ineffective."
Anticonvulsants, such as
gabapentin (Neurontin, Gabarone), have been successful in some more
severe cases. Gabapentin works through a receptor on the membranes of brain
and peripheral nerve cells. It binds to
calcium
channels and modulates calcium influx as well as influences GABergic
neurotransmission. Its effect is to deaden the irritated nerve
impulses in the dog's neck. In humans, gabapentin reportedly does not
interact with any other medications, and it is not metabolized, so it is
fully excreted in the urine and has no affect upon the liver. However, in
dogs, gabapentin is partially metabolized in the liver, and therefore the
prescribing neurologist may be expected to order periodic blood tests to
check the liver enzymes.
In human studies, gabapentin has caused side effects, including sleepiness, dizziness, and leg edema, which were minimized by increasing the dose gradually and by taking the drug with food.
Gabapentin also may be given in combination with NSAIDs. It has been recommended that gabapentin be dosed once every 8 hours, as it lasts in the systems of most cavaliers that long.
A newer anticonvulsant, pregabalin (Lyrica), is being prescribed by some neurologists in treating SM. It is closely related to gabapentin and was developed by Pfizer, which also developed gabapentin. Pfizer reports that pregabalin is more potent than gabapentin and achieves its effect at lower doses. Doses of pregabalin also reportedly have a longer lasting effect than gabapentin. No generic version is available, and as an exclusive brand, Lyrica is quite expensive in comparison to generic gabapentin.
Amitriptyline (Elavil, Tryptizol, Laroxyl, Sarotex) is a tricyclic antidepressant (TCA) by Merck which may be prescribed as an alternative to either gabapentin or pregabalin.
Oral opioids (pethidine, methadone, tramadol) are alternatives to anticonvulsants. Methylsulfonyl-methane (MSM) is recommended by some veterinary neurologists as a dietary supplement.
Drugs which reduce the production of cerebrospinal fluid, including proton pump inhibitors such as omeprazole (Prilosec, Losec, Omesec, Zegerid), and the diuretics, furosemide (Lasix, Diuride, Frudix, Frusemide) and spironolactone (Aldactone), are reported to be useful to reduce intracranial pressure. Long term use of omeprazole is not recommended by some neurologists, as its long term use reportedly has increased the risk of stomach cancer in lab rats. Short term use reportedly can cause a "profound and sustained increase in serum gastrin concentration in dogs." See June 2011 report.
Carbonic anhydrase inhibitors, such as acetazolamide (Diamox) also serve to decrease the flow of cerebrospinal fluid, but their adverse side effects of abdominal pain, lethargy, weakness, and bone marrow suppression limit long term use. Methazolamide (Glauctabs, MZM, Neptazane), also is a carbonic anhydrase inhibitor. Carbonic anhydrase is a protein which can affect fluid production in various parts of the body. Methazolamide reduces the activity of this protein. It's initial use was to treat glaucoma by reducing the amount of fluid produced in the eyes and therefore also reducing pressure in the eye.
Some neurologists have been prescribing cimetidine (Tagamet, Zitac), which is a histamine H2-receptor antagonist -- an antihistamine. Histamine contributes to inflammation and causes smooth muscles to constrict. Cimetidine is diffused into the cerebrospinal fluid and reportedly may contribute to reducing the flow of CSF. When taken with gabapentin, cimetidine also reportedly may increase the amount of gabapentin in the blood by decreasing its elimination. Therefore, when taken together, the dosages may require adjustment.
Some neurologists are prescribing amantadine (Symmetrel), which is used for control of the symptoms of Parkinson's disease in humans, together with gabapentin or pregabalin. Amantadine is believed to release brain dopamine from nerve endings making it more available to activate dopaminergic receptors
.-- alternative care
An herbal supplement which cavalier owners report calms dogs suffering from the symptomatic scratching of SM is a product called "Nerve Eight" or "Nerve 8" (manufactured by Nature's Sunshine of Provo, Utah), which consists of white willow bark (salix alba), black cohosh root (cimicifuga racemosa), capsicum fruit (capsicum annuum), valerian root (Valeriana officinalis), ginger root (zingiber officinale), hops flowers (humulus lupulus), wood betony herb (betonica officinalis), and devil’s claw root (harpagophytum procumbens).
Holistic supplements should be taken only if prescribed by a licensed veterinarian who also is holistically trained. A search webpage for finding holistic veterinarians in the United States is located at www.holisticvetlist.com.
Some owners of SM dogs report that periodic treatments of acupuncture provide relief.
-- surgery
The earliest reported surgeries to relieve CM was a series of suboccipital craniectomies and cranial dorsal laminectomies by a team of Belgium neurosurgeons in 2003. They had little success. Read their report here.
One form of surgery is called foramen magnum decompression (FMD), or suboccipital decompression, surgery. The surgeon removes the supraoccipital bone and the cranial dorsal laminae of the atlas. (See the decompression site over the occipital bone and foramen magnum, outlined in diagram at right.) Decompression surgery may include incising through the dura sac, a tough membrane which contains the brain inside of the skull, and installing a dural graft or shunt, to allow more space for the cerebellum and to reduce the pressure of the flow of CSF. In some surgeries, the entire occipital bone also is removed. A less frequent surgical procedure is subarachnoid shunting, which essentially is a salvage operation when the surgeon has no other surgical options. All FMD surgeries are technically difficult and should be performed only by experienced neurological surgeons.
Although this form of surgery often is successful, it may be expensive, and many dogs may either have a recurrence of the disease or still show signs of pain and scratching. Some post-operative pain is only temporary, due to leakage of CSF through the incision in the dura until that incision heals, or because the syrinx is still present after the surgery. The most frequent reason for recurrence reportedly is the development of post-operative scar tissue which compresses the cervicomedullary junction. Scar tissue has required additional surgery to remove it in about 25% of all FMD surgical cases. To avoid the development of scar tissue, it is important to not allow the dog too much freedom of movement or excitement during the healing process, which may last from three to six months.
In an effort to prevent such scar tissue from
re-compressing the junction, modified versions of FMD include
inserting
either a skull plate made of titanium mesh at the junction before closing
the incisions, (see photo), or covering the sutured dura with a tented graft
of swine intestine tissue, covered by a layer of the dog's fat tissue.
Decompression surgery is not expected to cure the SM. It is intended to reduce the pressure and stop the progression of the syrinxes. Damage done to the brain and spinal cord before the surgery usually will not be reversed, and most dogs will need to continue on medications afterwards, including gabapentin or pregabalin and cortisteroids, depending upon the severity of that damage before the surgeries. The neurologists also may recommend that the post-surgery patient undergo rehabilitation physical therapy, in part to offset debilitating effects to the muscles, which may result from long term doses of cortisteroids.
--- cranioplasty using titanium
The titanium procedure is called cranioplasty. Dr. Curtis W. Dewey, veterinary neurologist in New York, and Dr. Dominic J. Marino, board certified veterinary neuro-surgeon, also in New York, and Dr. Wayne L. Berry, veterinary neurologist in California inserting the titanium mesh in several surgeries thus far. And now other specialists, including Dr. Graham Oliver in the UK, are performing the cranioplasty procedure.
In a report published in July 2007 in Veterinary Surgery, Drs. Dewey and Marino wrote: "Foramen Magnum Decompression (FMD) with cranioplasty was well tolerated, with no intraoperative complications, and minor postoperative complications. Most dogs improved clinically, and none required further surgery at the original FMD site." Dr. Dewey also has reported that the "re-operation rate" has been reduced to 10% or less of all FMD surgeries with the titanium mesh cranioplasty. See more about Drs. Dewey and Marino under Current Research below.
--- cranioplasty using LactoSorb SE mesh
LactoSorb SE mesh is a biodegradable polymer designed to resorb in the human body by hydrolysis within a year. Dr. Thomas Schubert at the University of Florida has tried it instead of titanium mesh in cranioplasty surgeries performed on cavaliers. He since has switched back to using the titanium mesh, and he is waiting for more information on the long term results of surgeries using LactoSorb SE mesh. This product reportedly is equal in strength to titanium at initial placement, retains 70% of its initial strength for the first eight weeks, and then gradually is eliminated from the body. It is manufactured by Biomet Microfixation, LLC of Jacksonville, Florida.
--- duraplasty using swine tissue
The alternative of a tent graft of swine tissue and body
fat is called duraplasty.*
Dr. Andy Shores,
veterinary
neurologist at
Mississippi State University (previously at Auburn in Alabama), Dr. Jill
Narak, veterinary surgeon at the University of Tennessee in
Knoxville, and others have performed this procedure on at least 21 dogs,
most all of them cavaliers. Swine
intestinal submucosa was sutured over the cerebellum and brain stem in a
tented fashion (see photo). Fat tissue from the dog's gluteal region was then placed
over the site prior to routine closure.
* It is called duraplasty because the tissue is used as a substitute to the portion of the dura which was cut during the surgery.
In a report published in October 2009 at the American College of Veterinary Surgeons' annual symposium, the researchers stated: "Overall, recovery was considered to be good to excellent by owners. To date, none of the patients that have undergone this surgical procedure have required further surgical intervention due to postoperative compressive scar formation that has been reported in the previous literature. Follow-up time ranges from 1 week to 1 year. ... The use of the titanium mesh, placement of the screws, and the exothermic reaction of the overlying methyl methacrylate may contribute to tissue trauma. The authors conclude that with the results of this study, this procedure is clinically effective and the use of a titanium mesh, additional hardware and methyl methacrylate offers no advantage in canine COMS patients."
--- duraplasty using tissue adhesives
Synthetic dural substitutes in duraplasty procedures include inserting a soft foam consisting of a collagen-based matrix (e.g., DuraGen, by Integra LifeSciences Corporation). The collagen matrix supports the ingrowth of local cells while the matrix itself is fully resorbed over time. Dr. Michael Harrington, Animal Neurosurgery and Neurology, Murray, Utah, reportedly uses this technique.
--- syringosubarachnoid shunt
The shunt consists of a small silicone tube. One end is inserted into the subarchnoid space of the spinal cord below the syrinx, and the other end is inserted into the syrinx (see below, left). Thus it is called a syringosubarachnoid shunt (S-S shunt). Shunting drains the syrinx fluid into the subarachnoid space where the usual CSF circulation and absorption mechanisms exist. This should reduce the size of the syrinx and ease pain and other the clinical signs associated with CM/SM.
In
an April 2012 study of S-S
surgeries conducted on nine cavaliers and two Yorkshire terriers, Geoff
Skerritt and Dr. Luca Motta reported that:
"S-S shunting is a safe and relatively effective surgical technique that may improve the neurological signs and the quality of life of dogs affected by CM and associated SHM/SM. Postoperative complications or lack of clinical improvement may occur in a small number of cases and a secondary surgery may be needed. This study also suggests that the S-S shunt may lead to a satisfactory outcome in dogs where the FMD [foramen magnum decompression] technique has failed. Comparisons between different surgical techniques are needed to create objective criteria that may suggest which procedure will produce the best surgical results."
Mr. Skerritt and Dr. Motta may be contacted at ChesterGates Animal Referral Hospital, Telford Court, ChesterGates, Chester, UK, CH1 6LT, telephone 01244 853823, email GCSkerritt@aol.com.
--- conclusion about surgeries
Many of these studies have been "case studies", meaning that they were practiced without the controls normally included in clinical trials. In the July 2007 issue of Veterinary Surgery, Dr. Richard A. LeCouteur, board certified veterinary neurologist at the University of California, writes that "Medical history is replete with examples of invasive procedures and pharmacologic interventions that were widely accepted based on results of case studies, only to later be rejected based on results of controlled clinical trials. ... It’s time to adopt a more structured scientific approach to the study of the management of neurologic conditions that may benefit from surgical intervention. The randomized (preferably) double-blinded (preferably) placebo-controlled study is the gold standard for evaluating a new treatment intervention."
-- post-surgery soundwave therapy
Some cavalier King Charles spaniels, which have continued to suffer severe pain due to post-decompression surgery scar tissue, have been very successfully treated with an infrasonic instrument called AlphaSonic™. This infrasound technology generates multiple, random, chaotic sound waves in the range of Alpha (approximately 8 to 14 Hz), and unlike ultrasound waves, does not heat body tissue. Ultrasound uses a single high frequency (from 20,000 to1,000,000 Hz) to stimulate a localized area and heats tissue.
The manufacturer of the device represents that AlphaSonic™ is safer and more effective than ultrasound, penetrates deeper into the tissues, reduces inflammation, and softens scar tissue. It can be applied locally and at acupressure points, and is said to increase blood circulation and can allow the body to heal itself, much like the affects of acupuncture, but without the needles.
The device is electrically operated and looks very similar to an ultrasound unit. Dr. Ronald J. Riegel, DVM, who has studied the effects of the AlphaSonic™ since 2001, stated, "The goal of any physical therapy modality is to increase the circulation and increase the elasticity and flexibility of the tissue. the alphasonic absolutely increases circulation and allows the body to heal itself. The metabolism is increased, reducing recovery times".
Adequate hydration is important for optimum bodily function. The dog should be kept hydrated before, during, and after treatment with fresh clean water. Although the manufacturer reports that AlphaSonic™ is totally safe and that no negative side effects are known, any AlphaSonic™ treatments for dogs with veterinary conditions, especially those taking medication, should be performed only under the guidance of a qualified, licensed veterinarian. For more information about AlphaSonic™, contact Susan Stoltz at AlphaSonic, P.O. Box 2727, Valley Center, CA 92082, telephone 760-751-2836, email alphasonics@sbcglobal.net, websites www.alphasonic.com and www.makepaingoaway.com
Current Research
4April 2012: UK researchers find an association between syringomyelia and the cavalier's oversized cerebellum. In an April 2012 report, UK researchers Thomas A. Shaw, Imelda M. McGonnell, Colin J. Driver, Clare Rusbridge, and Holger A. Volk, confirmed previous studies that cavalier King Charles spaniels have proportionately larger cerebellums than other small breeds and Labradors. They also found an association between the CKCS's oversized brains and SM. 75 cavalier MRI scans were reviewed. They concluded:
"These findings support the hypothesis that it is a multifactorial disease process governed by increased cerebellar volume and failure of the CCF to reach a commensurate size."
4April 2012: RVC needs cavaliers to compare neuropathic pain medications for SM. The Royal Veterinary College is seeking UK and US cavaliers diagnosed with symptomatic CM and/or SM to participate in a study comparing two neuropathic pain medications. Eligible dogs must show clinical signs of neck/ back pain, air scratching, facial rubbing, screaming/ yelping episodes or wobbliness. Dogs with kidney or gastro-intestinal disease cannot be included.
The RVC and the Queen Mother Hospital Royal Veterinary College and Queens Veterinary School Hospital and Stone Lion Veterinary Group, all in the UK, as well as the College of Veterinary Medicine, Iowa State University, in Ames, Iowa USA, are participating. For more information, email tckcstrial@gmail.com or click here.
4April 2012: Geoff Skerritt and Dr. Luca Motta find shunt surgery successful for relieving SM pain. UK neurosurgeons Geoffrey Skerritt and Dr. Luca Motta report in an April 2012 study that:
"[Syringosubarachnoid shunt] S-S shunting is a safe and relatively effective surgical technique that may improve the neurological signs and the quality of life of dogs affected by CM and associated SHM/SM. Postoperative complications or lack of clinical improvement may occur in a small number of cases and a secondary surgery may be needed. This study also suggests that the S-S shunt may lead to a satisfactory outcome in dogs where the FMD [foramen magnum decompression] technique has failed. Comparisons between different surgical techniques are needed to create objective criteria that may suggest which procedure will produce the best surgical results."
The researchers performed surgeries on nine cavaliers and two Yorkshire terriers. Ten of the dogs survived the study. They also devised a Pain Score Scheme (see table above under Symptoms) to evaluate the levels of pain the dogs experienced both before and following the surgeries.
4December 2011: UK researchers confirm that cavaliers with only CM suffer pain and that CM/SM is progressive. In a December 2011 study at the Royal Veterinary College, researchers studied 49 clinically affected CKSCs. They found: (a) 25% did not have SM; (b) the severity of SM was positively correlated with patient age; and (c) there is a very high potential for CKCS with clinical signs of CM/SM to develop SM in more than one spinal cord region.
4October 2011: Univ. of Penna. cardiologists study torsemide as alternative to furosemide. University of Pennsylvania veterinary cardiologists report that they have tested the loop diuretic torsemide as alternative to furosemide in dogs with advanced heart failure, including a 12 year old cavalier. They have found torsemide "has several characteristics that make it suitable for treatment of advanced heart failure including longer half-life, increased potency of diuretic action, and anti-aldosterone effects."
4
October 2011: SM Breeding Protocol Statistics. In an October 2011 report of the statistical results of following the SM protocol, the researchers, Dr. Rusbridge, Penny Knowler, and A. K. McFadyen stated that:"This study investigated the early outcome of existing SM breeding guidelines. Six hundred and forty-three dogs, 550 Cavalier King Charles spaniels (CKCS) and 93 Griffon Bruxellois (GB), were identified as having either one (454 dogs) or both parents (189 dogs) with MRI-determined SM status.
• Offspring without SM were more common when the parents were both clear of SM (SM-free; CKCS 70 per cent, GB 73 per cent).
• Conversely, offspring with SM were more likely when both parents had SM (SM-affected; CKCS 92 per cent, GB 100 per cent).
• A mating of one SM-free parent with an SM-affected parent was risky for SM affectedness with 77 per cent of CKCS and 46 per cent of GB offspring being SM-affected.
It is recommended that all breeding dogs from breeds susceptible to SM be MRI screened; that the SM status at five years old is established; and all results submitted to a central database that can be used by dog breeders to better enable mate selection based on estimated breeding values."
4
September 2011: UK researchers examine distribution of pain-related neuropeptides in cavaliers with SM. They observe that CKCSs with clinical signs of SM also show disruption in the structure of their spinal cord's dorsal horn. See report summary. The researchers conclude:"This current study provides evidence to suggest that the disruption of the dorsal horn structure is a significant event in the production of clinical signs in CKCS. The spinal cord dorsal horn in symptomatic CKCS is significantly more asymmetric than that of control animals, whereas the asymptomatic CKCS have changes that are midway between control and symptomatic CKCS. This suggests the possibility that progression from mild to severe asymmetry in CKCS is associated with development of clinical signs; however such a conclusion cannot be definitively supported by this study because of the cross sectional nature of the data collected."
4
September 2011: Researchers find that SM is associated with degenerative changes in the spinal cord. In a study published in the Journal of Comparative Pathology, researchers H.Z. Hu, Clare Rusbridge, F. Constantino-Casas, and Nick Jeffery report that:"SM is associated with degenerative changes in the spinal cord and may develop through primary disruption of ependymal integrity followed by vascular hypertrophy and proliferation. Glial and fibrous proliferation appears to be associated with expression of clinical signs."
The ependyma is the epithelial membrane which lines the spinal cord. Vascular hypertrophy means the increase in the volume of blood vessels. Glial are cells that provide protection for the brain's neurons, among other things.
Commenting on the findings by one of the article's authors, Dr. Clare Rusbridge, she writes on her blog:
"The pathology suggested that the primary development of syringomyelia is associated with central canal dilatation and damage which is accompanied by blood vessel changes. This is an important finding because there is so much debate on how syringomyelia develops in all species."
4
August 2011: Head position affects extent of cerebellar herniation in MRI scans. UK researchers examining 14 CKCS MRI scans (7 with CM/SM and 7 with just CM) comparing scans in both extended and flexed head positions. In their report, they have found the degree of cerebellar herniation was significantly worse in dogs with a flexed compared to an extended head position. When cerebrospinal fluid (CSF) space between the cerebellum and brainstem was compared in CKCS with and without SM, there was a significant increase in CSF space in CKCS with CM alone compared to those with CM/SM when head position was flexed. Based upon their findings, they state that it may be appropriate to position patients in a more flexed head position for optimal imaging in order to identify morphologic changes more accurately. They stated that this is important to consider for imaging CKCS with CM especially when studying the pathogenesis of CM/SM.The researchers also found:
"When CSF space between the cerebellum and brainstem was compared in CKCS with and without SM, there was a significant increase in CSF space in CKCS with CM alone compared to those with CM/SM when head position was flexed. In their cine MR imaging study of CSF flow dynamics in CKCS with CM or CM/SM, Cerda-Gonzalez and others (2009a) found that turbulent CSF flow and jets are associated with SM presence and severity and CSF flow velocity at C2/3 is inversely related to the presence of SM. The reduced CSF space in CM/SM dogs reported in this study could explain this jet like CSF flow in dogs with CM/SM compared to those with CM alone."
This could mean that the severity of CM/SM, or even the presence or future presence of SM, could be predicted based upon the measure of cerebrospinal fluid space between the cerebellum and the brainstem. If so, this could go a long way to distinguishing whether a CM-only cavalier is either likely or unlikely to develop SM in the future. This distinction could be a way to fine-tune a breeding protocol, considering that we now know that over half of cavaliers with SM develop it after their 3rd birthday. If we could reliably count on this measurement of CSF space to tell us if a young dog will, or will not, develop SM in the future, then we could more reliably select SM-free breeding stock at a younger age than the present 2.5 years and the 3+ years the researchers may recommend in the future.
4
June 2011: Montreal team of researchers identify chromosome 2 region associated with Chiari-like malformation in the Brussels Griffon breed. See summary here. Researchers include Lemay P, Trinh QH, Dubé MP, Rusbridge C, Rouleau GA, and Kibar Z.4
June 2011: UK researchers find that CM is progressive in CKCSs; that foramen magnum size and cerebellar herniation increase significantly. UK researchers, including Drs. Rusbridge, Driver, and McGonnell, reported to the ACVIM in a June 2011 study that twelve CM-affected cavaliers' foramen magnums and the length of cerebellar herniation "increased significantly" between MRI scans which averaged 9.5 months apart. they concluded:"This work could suggest that overcrowding of the caudal cranial fossa in conjunction with the movements of cerebrospinal fluid and cerebellar tissue secondary to pulse pressures created during the cardiac cycle causes pressures on the occipital bone. This leads to a resorption of the bone and therefore an increase in caudal cranial fossa and foramen magnum size allowing cerebellar herniation length to increase."
4
June 2011: UK researchers report CKCS has relatively larger cerebellum than both small breeds and Labradors. In a June 2011 report to the ACVIM, UK researchers, including Drs. McGonnell, Driver, and Rusbridge, compared cerebellar size of cavaliers with other small breed dogs and with Labrador retrievers. They conclude: "Our findings show that the CKCS has a relatively larger cerebellum than small breed dogs and Labradors and there is an association between increased cerebellar volume and SM in CKCS."4
June 2011: Long Island Veterinary Specialists report 97.3% accuracy in thermography diagnosing Chiari-like malformation in CKCSs. Drs. Catherine Loughin and Dominic Marino released a June 2011 study of 105 cavaliers, comparing the results of medical infrared imaging (MII), also called thermography, with MRIs to detect the presence of CM. The results: "The top of head and front of head ROI [regions of interest] were 89.2% and 97.3% successful in identifying dogs with CLM. Based on these preliminary findings, MII may be a viable screening tool to detect CLM in dogs." Thermography does not require sedation.4
June 2011: Omeprazole profoundly increases dogs' serum gastrin concentration in two weeks. US researchers studying the effect of two weeks of omeprazole doses on healthy dogs reported "a profound and sustained increase in serum gastrin concentration in dogs. This effect is rapidly reversible after cessation of the treatment. No effect on calcium metabolism was observed."4
June 2011: Alastair Cockburn to study pain due to SM. The Universities Federation for Animal Welfare (UFAW) has awarded a Research Training Scholarship to Alastair Cockburn of the University of Bristol. He will investigate methods for assessing pain, underlying emotional state and quality of life in dogs with chronic pain conditions of syringomyelia and osteoarthritis. The aim of the research project is to deliver a useful clinical tool to measure chronic pain in dogs, a problem area due to the often very subtle changes in behavioral indicators of pain and the difficulty of assessing underlying emotional state and cumulative experience of pain – factors of critical importance in assessing quality of life.4
June 2011: UK study of 555 cavaliers shows percentage with SM up to 70% in older dogs with no symptoms. A UK study of 555 (reportedly) asymptomatic CKCSs found 25% of 12 month olds with syringomyelia, increasing to 70% in cavaliers 6 years and older. The researchers concluded:"The evidence for a lower prevalence in younger animals is more reliable (because of the higher numbers included in the present study and the lower likelihood of false inclusion) and this effect lasts until dogs are at least three years of age. This finding has important implications for the design of a screening test procedure and may conflict with the current recommendations that the optimum age for screening should be 30 months. These data would imply that it is probable that dogs aged up to three years may yet have reduced odds for the diagnosis of syringomyelia. However, there is a need for the dogs to be creened when they are reasonably young so that breeders can decide at an early stage whether their animals are suitable for breeding; many breeders would consider 36 months unduly old. ... The high lifetime prevalence of syringomyelia raises concerns for the welfare of the CKCS breed and also suggests that eliminating the genetic risk factors for the disease by selective breeding may be difficult, because the heritability has previously been shown to be complex, and the prevalence of the determinant genes within the population is therefore likely to be high. The true prevalence of syringomyelia in the general CKCS population is expected to be higher than that found in this sample population because symptomatic dogs were specifically excluded."
4
May 2011: Somatosensory-evoked potentials' (SEP) amplitude is more sensitive measure of spinal cord function in CKCSs with SM. UK researchers report that SEP amplitude at the C1 vertebra was a more sensitive measure of spinal cord function in CKCSs with syringomyelia, compared with results of EMG or TMMEP assessment. Measurement of SEP amplitude may have use as an objective assessment of the evolution and treatment of this disease. Read the details here.4
March 2011: UK researchers find that the development of syringomyelia is accompanied by alterations in cerebrospinal fluid composition. Read their summary here.4
February 2011: Rupert’s Fund Report for 2010. Rupert's Fund reports that in 2010, its fund raising paid for 29 dogs (all over 6 years except for one over 5 year years old male). The average age was 7.7 years and the oldest dog scanned was 12 years. Results: 18 CKCS were graded A (11 females and 7 males); 11 CKCS were graded D (6 female and 5 males). All had CM, two with only mild CM. Dr. Clare Rusbridge and Penny Knowler report:"Older dogs scanned have highlighted that SM can be late onset and/or progressive. Several dogs were selected because they already had previously scanned clear but had subsequently developed SM even after the age of 4 years. Such valuable additional information allows the researchers to investigate factors which might influence why some syrinxes progress rapidly and others don’t. Analysis of litters produced using the interim breeding guidelines revealed that higher numbers of dogs which were SM-clear over five years were produced if a parent was also clear of SM over 5 years.
"Donations from RF continue to fund MRIs. Priority is given to male dogs over 6 years, particularly if they have already had a SM-clear scan, but we are also interested in stud dogs of 5 years of age and bitches that have had a scan over 4 years of age or unknown MRI status over 8 years of age and asymptomatic. However, all requests made for Rupert's Fund are considered on an individual basis, and no one should be deterred in applying if they can justify how it helps the breed."
4
January 2011: Chiari-like malformation has been re-defined. On the website of syringomyelia researcher Dr. Clare Rusbridge, CM now is defined as "a condition characterized by a mismatch in size between the brain (too big) and the skull (too small). There is not enough room for the brain and the back part (cerebellum and medulla) is pushed out the foramen magnum." The foramen magnum is a hole in the back of the skull -- in the occipital bone -- leading to the spinal cord. Dr. Rusbridge goes on to explain that the cavalier appears to have a brain more appropriate for a bigger dog. Go here for more discussion.4
January 2011: UK researchers find distribution of SM along entire spinal cord of cavaliers; syrinx size positively correlated with age. In MRI studies of 49 cavaliers, reported in 2011 in the Veterinary Journal, Dr. Clare Rusbridge and others found that "Syrinx formation was present in the C1–C4 region and in other parts of the spinal cord. The maximal dorsoventral syrinx size can occur in any region of the spinal cord." Seventy-six per cent of CKCS with a cranial cervical syrinx also had a syrinx in more caudal spinal cord regions.They concluded that, "MRI restricted to the cervical region may underestimate the extent of SM and the severity of the disease process in the majority of dogs." Therefore, so-called "mini-MRI-scans" of only the cervical region, such as those scans for breeding protocol purposes, may not necessarily locate all syrinx which an SM-affected cavalier may have. They also found that total syrinx size positively correlated with the age of the dog.
4
October 2010: Long Island Veterinary Specialists has started "The Canine Chiari Institute", with the mission "To improve the lives of dogs afflicted with Chiari-like Malformation and related disorders through research and continuing education." Its website is under construction, but parts of it are operative.4
October 2010: Current results of following the SM Breeding Protocol. In an interim report of the statistical results of 393 cavalier offspring of MRI-scanned breeding stock, Dr. Clare Rusbridge stated that:• Matings of Code A CKCS to Code A CKCS have produced 75.9% offspring with no SM.
• Matings of Code A CKCS to either Code D, E, or F CKCS have produced 41.9% offspring with no SM.
• Matings of Code A CKCS to unscanned CKCS have produced 50.0% offspring with no SM.
• Matings of Code D CKCS to Code D, E, or F CKCS have produced no offspring free of SM.
4
June 2010: Canadian researchers find TMMEP, SSEP, SEP and BAER testing for SM do not work. In a 2010 report, a group of Canadian neurologists tested fifty cavaliers to evaluate the validity of BAER as well as transcranial magnetic motor evoked potentials (TMMEP), somatosensory evoked potentials (SSEP), and spinal evoked potentials (SEP), compared to MRIs. The researchers found: "TMMEP, SSEP, SEP and BAER do not appear to be valuable tests in detecting functional abnormalities of the motor and sensory pathways throughout the central nervous system of CKCS dogs with and without neurological signs secondary to SM diagnosed by MRI."They also found a significant linear correlation between the severity of neurologic dysfunction and size of the syrinx, with a larger syrinx being associated with more severe neurologic signs.
4
June 2010: UK researchers report severe SM relates to greater hindbrain - caudal fossa volume mis-matches. In an abstract (A Comparison of Ventricular and Caudal Fossa Volumes in Cavalier King Charles Spaniels > 5 years of age that have not developed Syringomyelia vs those Affected when < 2 years) presented to the BSAVA by Colin Driver, Dr. Rusbridge, et al., they found that severe SM in cavaliers under 2 years old is associated with greater mis-match between hindbrain and caudal fossa volume than found in older CKCSs with CM but no SM. MRIs of 21 cavalier King Charles spaniels under 2 years affected with CM/SM, and 14 CKCSs over 5 years with only CM were analyzed.4
June 2010: A UK study of 59 cavalier King Charles spaniels (71% having syringomyelia) confirms earlier findings that the variations in the dimensions of the cavaliers' posterior cranial fossa* is not associated with syringomyelia. Instead, this study, led by Colin Driver, BSc, BVetMed (Hons), MRCVS, points to two other possible connections. First, they found that a cavalier with a higher volume of parenchyma (brain matter) within the cranial fossa is more likely to have SM, and the greater the volume of parenchyma, the larger the syrinx. They state:"There was a significant difference in [percentage of parenchyma within the caudal cranial fossa] CCFP between those without or with SM. ... More marked brain and skull volume mismatches result in SM because a higher parenchyma percentage (CCFP) is associated with the presence of a cervical syrinx. This could explain the high incidence of SM secondary to CM in CKCS reported by Rusbridge and Knowler (2003). Although statistically significant, the difference in means for CCFP between the two groups appears small. It is therefore hypothesised that only a small difference in parenchymal volume is necessary to influence the development of a cervical syrinx. Furthermore, as the total volume of parenchyma and ventricular CSF within the CCF correlates with cervical syrinx dimensions, it can be hypothesised that more marked overcrowding of the caudal fossa results in greater compression of the subarachnoid space and subsequent syrinx dilatation."
Second, they also found a direct relationship between between the dimensions of the ventricles** and the size of the syrinx. They state:
"Furthermore, there is an association between ventricle and syrinx dimensions which supports the theory that SM development is the result of altered CSF dynamics."
*The posterior (or caudal -- for "rear") cranial fossa is part of the cavity within the skull. It contains the brainstem and cerebellum, and towards its rear, it is enclosed by the occipital bone, which also frames the opening called the foramen magnum.
**Brain ventricle: One of a system of four communicating cavities within the brain that are continuous with the central canal of the spinal cord. The four ventricles consist of the two lateral ventricles, the third ventricle and the fourth ventricle.
The researchers also discuss some What-Could-Be theories (a few admittedly are laden with technical verbiage): (1) "CM might be the result of paraxial mesoderm insufficiency during embryogenesis"; (2) "There is failure of communication between the paraxial mesoderm and the cranial somites with the closing neural tube, resulting in loss of coordination between skull and brain growth (paraxial mesoderm forms the supraoccipital bone, somitic mesoderm forms the exoccipital and basioccipital bones)"; (3) "Overgrowth of the cerebellum causes the mis-match because CKCS have proportionately more hindbrain parenchyma than other small breed dogs"; and (4) "Early growth plate closure may result in CM because despite the dynamic nature of osseous tissue, it would be unable to accommodate the developing brain."
They concluded that:
"The mild but significant difference of CCFP in CKCS with or without SM reflects the clinical difficulty in identifying those dogs that will develop SM. This study does not correlate the presence of SM with clinical signs or disease progression, which would be important for guiding the choice of therapeutic intervention. It therefore remains appropriate to continue to make clinical decisions on the basis of severity of clinical signs. Further studies evaluating these measurements as prognostic indicators are therefore warranted."
For more on this 2010 UK research report, go here and here. See, also 2009 ECVN abstract
.4
May 2010: Dr. Rusbridge reports genetic researchers may have found the site for SM on the cavalier's genome. In a May 20, 2010 update on her website, Dr. Rusbridge publishes an interim report in highly technical wording, which states that they have located a haplotype which contains mutations in SM-affected dogs and does not contain such mutations in unaffected cavaliers. Gene sequencing and additional mapping of the locus is under way.4
May 2010: Dr. Clare Rusbridge says microchips can interfere with MRI scans. Dr. Rusbridge stated that if a microchip is located near the upper spinal column being scanned, it could block the view of a syrinx. She said that a microchip will warp the image, resulting in a hole in the scan. She recommended that microchips be placed as low as possible over the thoracic vertebrae. Dr. Rusbridge spoke on May 2, 2010 at a syringomyelia symposium sponsored by the Griffon Bruxellois Club of the UK.4
May 2010: Dr. Sarah Blott issues her first report on using estimation of breeding values (EBVs). She writes in her May 2010 article:"EBVs will allow breeders to distinguish between potential parents of high and low risk, after removing the influence of life history events. Analysis of current population structure, including numbers of dogs used for breeding, average kinship and average inbreeding provides a basis from which to compare breeding strategies. Predictions can then be made about the number of generations it will take to eradicate disease, the number of affected individuals that will be born during the course of selective breeding and the benefits that can be obtained by using optimisation to constrain inbreeding to a pre-defined sustainable rate."
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April 2010: Dr. Thomas Schubert uses LactoSorb SE mesh instead of titanium in CM cranio-plasty surgeries. LactoSorb SE is a biodegradable polymer designed to resorb in the human body by hydrolysis within a year. It is being used instead of titanium mesh in cranioplasty surgeries performed on cavaliers by Dr. Thomas Schubert at the University of Florida. This product reportedly is equal in strength to titanium at initial placement, retains 70% of its initial strength for the first eight weeks, and then gradually is eliminated from the body. It is manufactured by Biomet Microfixation, LLC of Jacksonville, Florida.4
March 2010: UK researchers ask owners to describe how their SM-affected cavaliers behave. Drs. Lynda Rutherford and Holger Volk of The Royal Veterinary College's neurology service offer an on-line questionnaire for owners to complete, about the impact of SM on the owner's dog and the owner's life. They state, "It is also important to consider the general 'happiness' in a breed as this might have an impact on how an animal can live with a certain condition. We hope this information will help other owners caring for dogs with SM as well as veterinary surgeons in communicating issues associated with the disease."This is available to cavalier owners worldwide. Go to http://www.surveymonkey.com/s/3XT8BPV and enter the password CKCS3 to start the questionnaire. If you wish, all information you give will be anonymous and untraceable.
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Ruperts Fund lets every single one of us do something positive for the breed we love. All that is asked is that donations be made in UK pounds sterling, and that the minimum amount be 10 UK pounds. If you use PayPal, it’s really easy to make donations. You can select the currency (which means the researchers get the most out of your donation if you pick "pounds sterling"). If you are in the UK, and can write sterling cheques, you can make donations this way as well. Go to http://rupertsfund.com and follow the instructions.
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February 2010: MRI scans of Australian CKCS breeding stock shows 50% with SM. Dr. Georgina Child, board certified veterinary neurologist at the Small Animal Specialist Hospital in North Ryde, NSW, Australia, spoke to the CKCS Club of NSW about syringomyelia this month and reported that of 60 cavaliers which have been MRI scanned under the SM breeding protocol, 50% have been found to have syrinxes on their MRIs. None of these scanned dogs had any symptoms of SM, and all were potential breeding stock. Their syrinxes ranged from 2 mm to over 5 mm in size.4
October 2009: Auburn University researchers use swine tissue and body fat to prevent scar tissue after CM surgeries. Veterinary surgeons, including Dr. Andy Shores, board certified neurologist at Auburn, and Dr. Jill Narak, now at the University of Tennessee, and Dr. Michelle Carnes, now at Veterinary Specialists of South Florida, have performed foramen magnum decompression (FMD) surgeries on 14 dogs, including 11 CKCSs. Instead of inserting titanium mesh when closing the incision, they performed a duroplasty using swine intestinal submucosa and covering it with fat tissue graft (FAATG) from the dog's gluteal region. :"In dogs that require FMD in the treatment of COMS, this modified technique using a FAATG should be considered. Current clinical outcomes of patients that were treated for COMS using this technique showed excellent results similar to current published literature without intraoperative complications and clinical improvement with a decrease in clinical signs postoperatively. The use of the titanium mesh, placement of the screws, and the exothermic reaction of the overlying methyl methacrylate may contribute to tissue trauma. The authors conclude that with the results of this study, this procedure is clinically effective and the use of a titanium mesh, additional hardware and methyl methacrylate offers no advantage in canine COMS patients."
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August 2009: UK researchers find no significant difference in spinal canal widths of 59 SM and 19 non-SM cavaliers.4
August 2009: UK researchers find that cavaliers do not have a proportionately smaller caudal fossa compared to other small breeds, but that the CKCS's brain is comparatively large. They wrote:"When compared with Labradors, CKCS had proportionately the same volume of parenchyma in their caudal fossa, hence there is a mismatch of volumes with too much parenchyma in a too small caudal fossa causing overcrowding. ... Other small breeds of dogs had a proportionately smaller volume of parenchyma in their caudal fossa which can explain why, despite having a similar sized caudal fossa to CKCS, they do not experience overcrowding. It is hypothesised that through the miniaturisation process of other small dogs, both the cranium and brain are proportionately smaller but in CKCS only the cranium has reduced in volume, hence why there is a higher incidence of CM in CKCS than other small breeds.
"Cavalier King Charles spaniels also had a greater percentage of their cranial fossa filled with parenchyma (cranial fossa parenchyma percentage) compared with small breeds and Labradors which had a similar percentage. Overcrowding in CKCS might therefore occur due to a mismatch in volumes in both the caudal fossa and cranial fossa of the skull, suggesting the cranial fossa is also involved in the pathophysiology of CM."
A possible cause of CM? In the same 2009 report comparing the cerebral cranium volumes of the CKCS with those of other small breeds and the Labrador retriever, Hannah Cross and Drs. Claire Rusbridge and Rodolfo Cappello conclude:
"The results support mesoderm* insufficiency or craniosynostosis* as the pathogenesis of Chiari-like malformation (CM) in CKCS. It presents evidence for overcrowding of the caudal fossa due to a mismatch of brain parenchyma and fossa volumes as to why CKCS and not other small dogs are affected.
"*The mesoderm is the middle of the three primary germ cell layers -- the others being ectoderm and endoderm -- in the early stage of an embryo. The mesoderm is responsible for developing various tissues and structures, such as bone, muscle, connective tissue, and the middle layer of the skin. Mesoderm insufficiency during embryology may cause insufficient scope for the mesoderm and ectoderm layers to develop. C
raniosynostosis is the premature closure of the skull's growth plate.4
May 2009: Cavalier fetal and neonatal specimens show signs of CM. Dr. Imelda McGonnell of the Department of Veterinary Basic Sciences, The Royal Veterinary College, has been leading a study looking at anomalies in different stages from the cavalier's early growth in the uterus to its maturity. The study has been examining aborted fetuses and deceased young puppies that have died for any reason. In an interim report, Dr. McGonnell advises that abnormal cell division in the immature occipital bone may cause growth of the skull to not keep up with the growth of the cerebellum. She writes:"Anatomical investigations have shown that the occipital bone overlying the cerebellum has an abnormal bulge in the centre. These investigations also show that the cerebellum is compressed in CKCS foetuses at birth. However this compression is not yet sufficient to cause descent of the brain into the foramen magnum. The region of the compression in the brain corresponds to the region where we see the bulge in the bone. It suggests that the abnormal skull is compressing the brain. When we looked at the occipital bone in more detail, using sectioning, we saw that there was a region where there were more cells than normal – this was the region of the bulge. These cells were also immature – they had not formed proper bone. We looked at the part of the spinal cord nearest the brain but did not see SM. We will continue to examine the remainder of the spinal cord.
"When we looked at the cerebellum, we also found that there were more cells in parts of the cerebellum. When we counted the numbers of cells that were dividing, they were statistically significantly increased. Usually if there are too many cells being produced, we see lots of cells dying. However we found there were fewer cells dying. Both the increased cell division and reduced cell death make the cerebellum bigger. We also saw that some cells in the cerebellum that control co-ordination of movement were also not properly formed. This all tells us that both the brain and the bone are growing too much and that as a result, some of the cells are more immature at birth than they should be.
"This all points to this condition being caused by abnormal cell division. Importantly, it tells us that the brain and bone are not able to communicate with each other. In the normal situation, if the brain was growing too much, the bone should keep up with it. In the CKCS this relationship is lost.
"We will follow up these findings by investigating what is controlling the cell division in the brain and bone. We will also investigate why these two tissues are unable to communicate with each other."
Owners willing to participate should contact Sheena Stevens in Devon, UK, telephone 01884 821080, email Kilnshena@hotmail.com The nervous system degenerates rapidly after death and must be handled appropriately, so please contact Ms. Stevens as soon as or ideally before the dog has been euthanatized.
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April 2009: Dr. Clare Rusbridge has introduced her website, veterinary-neurologist.co.uk, which discusses SM extensively, as well as other neurological disorders which she has researched. Her doctoral thesis, a 200+ page book, Chiari-like Malformation and Syringomyelia in the Cavalier King Charles Spaniel, also is available online.4
April 2009: German study of the volumes of cranial cavities in Cavaliers with Chiari-like malformation and other brachycephalic dogs concludes "that descent of the cerebellum into the foramen magnum and the presence of syringohydromyelia in CKCSs are not necessarily associated with a volume reduction in the CF of the skull." The study included 40 Cavaliers and 25 dogs of other brachycephalic breeds. March 2009: Study finds that Cavaliers have shallower caudal cranial fossa and abnormal occipital bones than control breeds. In a 2009 Scottish study led by Dr. Jacques Penderis, of 70 Cavaliers and 80 dogs of other breeds, the researchers found that "all [of the] CKCSs had abnormalities in occipital bone shape. ... CKCSs had a shallower caudal cranial fossa and abnormalities of the occipital bone, compared with those of mesaticephalic dogs. These changes were more severe in CKCSs with syringomyelia."4
January 2009: Drs. Cerda-Gonzalez and Olby find occipital hypoplasia to be the most important factor associated with neurologic signs of SM. Drs. Cerda-Gonzalez and Olby and others report in Veterinary Radiology & Ultrasound that:"Factors associated with the presence of neurologic signs [of SM] included syringohydromyelia and the ratio of caudal fossa/total cranial cavity volume; dogs with signs had significantly larger syringo-hydromyelia than asymptomatic dogs. Caudal fossa size was not associated with syringohydromyelia. A positive association was identified between foramen magnum size and length of cerebellar herniation. The prevalence of craniocervical junction abnormalities is high in Cavalier King Charles Spaniels. While several factors are associated with neurologic signs, occipital hypoplasia appears to be the most important factor."
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November 2008: Rusbridge's & Knowler's "Summary of genetic studies of Chiari-like Malformation with Syringomyelia (CM/SM) in the Cavalier King Charles Spaniels (CKCS)". Dr. Clare Rusbridge and Penny Knowler have published an updated summary of the genetic studies of CM and SM in the Cavalier. Read it here. They also are seeking MRI scans of dogs 5 years old or older and which do not have SM, along with MRIs of those dogs' family members. Here is there introduction to their Summary:"If we find the gene/s it is possible to prevent CM/SM rather than treat it and the fact that Clare was able to obtain collaboration with such an eminent geneticist as Dr Guy Rouleau has made this a possibility. We still have a way to go with this complex disorder. Unlike Chiari-like malformation, Syringomyelia is an acquired condition and a syrinx may develop at different rates over a period of time. Some dogs may never develop symptoms so you wouldn't know it was there. However these dogs when bred together can produce puppies with large painful syrinxes. This is our focus. Dogs that have pain and suffer. To help find all the factors that contribute to the formation of a syrinx we need to find 'normal' cavaliers. We are looking for dogs that been MRI'd over 5/6 years or older who DO NOT have Syringomyelia and their relatives if possible. Please help. I have written to Lesley Jupp and asked for our request to be passed to Regional Clubs but it is the ordinary members that make up a club and you can make a difference by having your older dogs scanned or encouraging information to be shared if you know of any."
The MRI report and pedigree should be sent to Clare (email neuro.vet@btinternet.com) or Penny (email penny.knowler@ntlworld.com).
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November 2008: Fetal and neonatal specimens of Cavaliers: Dr. Imelda McGonnell of the Department of Veterinary Basic Sciences, The Royal Veterinary College, has been leading a study looking at anomalies in different stages from the Cavalier's early growth in the uterus to its maturity. The study has been examining aborted fetuses and deceased young puppies that have died for any reason. In an interim report, Dr. McGonnell advised that little or no cerebellar herniation has been observed at birth. The researchers have not seen a single case of proper cerebellar herniation in any of the stillborn pups submitted. Owners willing to participate should contact Sheena Stevens in Devon, UK, telephone 01884 821080, email Kilnshena@hotmail.com The nervous system degenerates rapidly after death and must be handled appropriately, so please contact Ms. Stevens as soon as or ideally before the dog has been euthanatized.4
October 2008: Dr. Rusbridge Revises CM/SM Treatment Options Chart. Dr. Clare Rusbridge has updated her diagram of how to treat Cavaliers and other dogs showing clinical signs of pain and discomfort with MRI diagnosis of CM/SM. See her 2008 CM/SM Treatment Algorithim.4
October 2008: UK Kennel Club Plans Standardization of MRI Scanning for Syringomyelia. In July 2008, the UK Kennel Club held a conference which included veterinary neurologists, geneticists, CKCS club representatives, and the Animal Health Trust (AHT), at which they agreed to develop a protocol to standardize MRI scans for syringomyelia, which would include setting a minimum age for scans. On October 24, the panel of veterinary neurologists involved presently in MRI scanning met in London, and agreed upon a proposed "British Veterinary Association (BVA) / Kennel Club (KC) Syringomyelia MRI screening scheme" for scanning and evaluation. The panel will present their proposal to the BVA and KC at a meeting set for November 25. The panel requests that all CKCS clubs encourage their members to send copies of their Cavaliers' MRI scan results to AHT. Contact Dr. Blott at the Genetics Department, Animal Health Trust, , Lanwades Park Kentford, Newmarket, Suffolk CB8 7UU, telephone +44 1638 751000, fax +44 1638 555606, website: www.aht.org.uk4
October 2008: Dr. Blott's Preliminary Report on SM Gene Research. Dr. Sarah Blott, of UK's Animal Health Trust, reported to the UK neurologists at their October 24 meeting that:"Early estimates of the heritability of SM suggest it is
around 0.7-0.8 or that 70-80% of the variation between individuals is
genetic in origin and about 20-30% is environmental. The heritability is
sufficiently high that genetic selection against the disease should be very
successful. Heritabilities for CM, cerebellar herniation and ‘medullary
kinking’ are also very high. Genetic correlations between these traits and
SM are positive and less than one. This suggests that different genes may be
controlling the expression of SM and CM and that it will be possible to
select against SM even if dogs have CM.
"The computer model can also take account of other inherited disease, such
as mitral valve dysplasia, and generates an Estimated Breeding Values (EBV)
for each dog. An EBV is the best measure available for complex traits of the
genetic potential of individuals. EBVs can be calculated for most CKCS even
if they have not been MRI scanned, as long as they are related to dogs that
have been scanned. The predicted EBV of an individual is half the EBV of its
sire plus half the EBV of its dam. All dogs will have an EBV at birth but
the EBV may be modified by the dog’s subsequent clinical record or MRI scan
and by information coming from other relatives. The EBV becomes more
accurate as information on offspring becomes available, because we start to
gain insight into which half of the sire and dam genes were actually
inherited when we see transmission of the genes to offspring. The accuracy
of the EBV increases with numbers of offspring and this may take some time
to achieve."
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May 2008: Companion Animal Welfare Council (CAWC) Workshop Report on SM in the CKCS. A workshop of the CAWC has issued a report on syringomyelia in the Cavalier King Charles spaniel. It states:"Recent efforts, as yet unpublished, to learn more about the genetics of the disease have indicated that it has a high heritability. One implication of this is that intense efforts to eliminate it through selective breeding might be effective over a rather few generations (eg 4 or 5). However, syringomyelia is not the only genetic problem in CKCS, mitral valve disease also has a high prevalence and the need for simultaneous tackling of these diseases (and avoiding further inbreeding) complicates the approach.
"Efforts at the Animal Health Trust are being directed to the development of optimum breeding strategies and the establishment of a web-based interface for use by breeders to help them identify potential mates for their dogs that present the least risk of perpetuating genetic diseases. A third element of the programme will involve educational initiatives for breeders on these matters.
"CAWC is keen to assist in driving forward initiatives for tackling welfare problems that have arisen through selective breeding of companion animals. At this workshop various actions were proposed or emerged, including: That there seems to be a need for further debate about the relative merits of the three approaches to tackling these kinds of welfare problems (breeding to reduce prevalence or eliminate within the breed, outbreeding to reduce prevalence or eliminate, or ceasing to breed at all from potential carriers). That breed clubs and the Kennel Club might work more closely together further to find ways to make more health and welfare information available. That scientists studying the epidemiology and genetics of the disease should get together with breed club representatives, facilitated by the Kennel Club, to devise a scheme for collection of data on the epidemiology of the disease (including systems for assessing MRI results), for use in pursuit of its control or elimination.
"CAWC will explore ways to facilitate the first of these and looks forward to hearing of timescales for and progress with the second two initiatives and also of progress with other initiatives outlined at the workshop, including: development of genetic tests, development of web-based mate-selection advice, and initiatives for education and provision of better information on health and welfare for prospective owners."
The CAWC provides "independent advice and to inform public debate on matters relating to the welfare of companion animals. It pursues its objectives through undertaking independent and objective studies of companion animal welfare issues, identifying where further action is required, and preparing and publishing reports thereon. The Council is open to requests for objective views, advice and the carrying out of independent studies on issues concerned with the welfare of companion animals. CAWC is funded by the Welfare Fund for Companion Animals." CAWC may be contacted at CAWC Secretariat, The Dene, Old North Road, Bourn, Cambridge CB23 7TZ, website: www.cawc.org.uk, email: cawc@cawc.freeserve.co.uk
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May 2008: Role of Estimated Breeding Values (EBV) for SM to grade genetic potential of Cavalier breeding stock. Dr. Sarah Blott, PhD (Quantitative Genetics), MSc (Animal Breeding), of the Genetics Department of the Animal Health Trust, in the UK, has published her notes from a May 18, 2008 presentation, "Genetics of Syringomyelia and Breeding Strategies to Reduce Occurrence" at the Cavalier King Charles Spaniel Clubs Liaison Meeting in the UK. Read it here. Dr. Blott may be contacted at Genetics Department, Animal Health Trust, , Lanwades Park Kentford, Newmarket, Suffolk CB8 7UU, telephone +44 1638 751000, fax +44 1638 555606, website: www.aht.org.uk4
April 2008: CM/SM Status Report From Geoffrey Skerritt. Mr. Geoffrey Skerritt, BVSc, MIBiol ,CBiol, DipECVN, FRCVS, reported in April 2008 that SM is a "clinical disaster" facing Cavalier King Charles spaniels. He wrote:"At ChesterGates Referral Hospital, and before that Cranmore Veterinary Centre, we have seen approximately 600 Cavalier King Charles Spaniels since we were aware of this condition, and our experience is that about 85% of these are showing clinical signs and/or MRI features of CM. Work by geneticists has established that this is an inherited disease although there is some dispute about the precise factors that are genetically transmitted. The inheritance not only results in visibly affected dogs but, as carrier status almost certainly exists, an appreciable proportion of the 15% are capable of transmitting the condition. So, it is likely that there is only a handful of Cavaliers that do not possess genetic factors for CM, and maybe none in the UK. Admittedly CM is not a fatal disease on its own but it can be severely disabling and it seems that some individuals suffer considerable discomfort and actual pain; human Chiari patients can give a clear description of the sensations that result from the disruption of nervous tissue in the development of syringomyelia.
"To ignore CM and continue breeding of Cavaliers with no effort to exclude affected dogs is frankly irresponsible. The situation is almost irretrievable because of the high incidence, and success in saving the breed will take hard decisions and 100% cooperation by breeders. The Kennel Club could be highly influential in the rescue effort; awards in the show ring should not be given to affected dogs. All Cavaliers should be screened with MRI and provided with a certificate that clearly states the MRI findings. I should add that MRI is a highly accurate and advanced technique which can clearly differentiate between dogs that have CM and those that do not. However, it does not identify carriers that have no evidence of the condition. Incidentally I feel that there should be no need for sponsorship of an MRI screening scheme except for pet owners of poor means. Breeders should be prepared to pay something for the service – we, the operators of MRI have already made a huge reduction in the cost of scanning on the screening scheme."
Mr. Skerritt may be contacted at ChesterGates Animal Referral Hospital, Telford Court, ChesterGates, Chester, UK, CH1 6LT, telephone 01244 853823, email GCSkerritt@aol.com. (April 2008).
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March 2008: Identification of Genes Causing Chiari I Malformation with Syringomelia in the CKCS. Dr. Zoha Kibar, at the University of Montreal, is planning a study to identify and characterize the gene(s) defective in Chiari-like malformation (CM) and SM. She states that, "Identification of the CM/SM gene(s) will allow the development of a DNA test that will allow breeders to identify carriers and devise breeding strategies with the aim of reducing or eliminating this devastating condition in the dog. These studies will also help us better understand the pathogenic mechanisms involved in CM/SM for better treatment strategies."Dr. Kibar is a molecular geneticist in charge of fine mapping and identification of the gene(s) at the Centre for the Study of Brain Diseases, CHUM – Montreal. For more information about Dr. Kibar, click here. The aim of the project is to identify markers and genes for SM, so that dogs can be conclusively tested at birth. Financial sponsors thus far include AKC Canine Health Foundation, American Cavalier King Charles Spaniel Club Charitable Trust, and Cavalier King Charles Spaniel, USA Health Foundation.
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March 2008: Transcranial Magnetic MEP to assess motor and sensory pathways in Cavaliers' spinal cords. Drs. Roberto Poma and K. C. Wolfe of the Ontario Veterinary College, University of Guelph, in Ontario, report they are conducting a study to assess the functional integrity of the descending (motor) and ascending (sensory) pathways in CKCS dogs with magnetic resonance imaging of cervical spinal cord and brain suggestive of SM and Chiari-associated SM. They state:"Stimuli applied to the scalp can excite the motor pathways, inducing muscle action potentials from fore- and hind limbs. A motor evoked potential (MEP) can be elicited by transcranial magnetic stimulation. Transcranial Magnetic MEP (Transcranial Magnetic Motor Evoked Potential) is not painful and can be performed with or without sedation. ... In veterinary medicine especially, TMMEP has been used to assess the correlation between severity of clinical signs and motor evoked potentials (MEP) in large-breed dogs with cervical spinal cord diseases, in Doberman Pinscher with cervical vertebral instability and in chondrodystrophic breeds with intervertebral disc disease. ... In CKCS dogs with clinical signs of SM, intermittent neck pain is the most common neurological sign observed. The pain is likely to be multifactorial and related to obstruction of CSF flow and spinal cord damage. Damage to the dorsal horn of the spinal cord is a key feature in the chronic pain of SM The dorsal horn of the spinal cord is the most important relay center for transmission of sensory information to the brain. Somatosensory evoked potentials of the cervical spinal cord were performed in human patients affected by SM. Abnormal SEP latencies were detected in patients with neck pain supporting a sensory etiology affecting the cervical spinal cord of dogs affected with SM."
Drs. Poma and Wolfe may be reached at telephone 519-824-4120, ext. 54129, email rpoma@uoguelph.ca
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January 2008: "Radiographic morphology of the cranial portion of the cervical vertebral column in Cavalier King Charles Spaniels and its relationship to syringomyelia". Researchers at the Department of Veterinary Medicine, University of Cambridge, England (Stalin CE, Rusbridge C, Granger N, Jeffery ND) published in January 2008 a report of their study to compare radiographic morphology of the atlantoaxial region between Cavaliers and other breeds and determine whether there was an association between radiographic morphology of the atlantoaxial region and syringomyelia in CKCSs. Sixty-five Cavaliers and 72 other dogs were examined. The result was that "the amount of overlap of the atlas and axis and the relative size of the spinous process of the axis were significantly smaller in CKCSs than in dogs of other breeds. However, the amount of widening of the atlantoaxial joint that occurred when the neck was moved from a neutral to a flexed position was not significantly different between groups, and no association was detected between syringomyelia and excessive atlantoaxial joint space widening or between syringomyelia and an excessively small axial spinous process." They concluded "that these differences do not account for why some CKCSs develop syringomyelia and others do not."4
November 2007: Dr. Rusbridge's Syringomyelia News Winter 2007 Research Update4
November 2007: Study of the treatment of neuropathic pain associated with syringomyelia in Cavalier King Charles Spaniels. The Royal Veterinary College of the University of London is conducting a clinic trial, beginning in November 2007, to assess the therapeutic value of a novel pharmacological agent in CKCSs with syringomyelia. Dogs enrolled onto the study will be treated with this novel agent, given orally, for 14 days. The researchers anticipate that the novel agent will ease clinical signs and offer a therapeutic advantage over current analgesic remedies. Eligibility Requirements: CKCS with SM confirmed by a MRI within 8 months prior to enrollment; clinical signs of: scratching, pain, sensitivity to touch; dogs must weigh 4Kg-12Kg; dogs must be aged 1yr – 10yrs; dogs currently on other pain medications are still eligible but a changeover program will be implemented.Participating dogs will receive free MRIs, CSFs, pre-anaesthetic blood profiles, and neurological evaluations if not been performed in the last 8 months. As a post study incentive, a veterinary care voucher will be given and may be used towards treatment of the condition. Contact: Clinical Investigation Centre, Veterinary Clinical Sciences, Royal Veterinary College, Tel: (01707) 666605, email: cic@rvc.ac.uk.
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October 2007: "The search for the gene(s) predisposing to Chiari 1 malformation with syringomyelia." At the International Symposium on Syringomyelia held in October 2007 in Rugby UK, Dr. Guy A. Rouleau, (M.D., Ph.D., Director, Centre for the Study of Brain Diseases, Montreal, Canada) reported: "Pedigree analysis in a large database of over 5,500 CKCS has suggested that Cm/SM is inherited where all clinically affected dogs share a small number of common ancestors. To date, no genetic factor predisosing to CMI has been identified in either humans or dogs. He further stated:"The CKCS is the only known naturally-occurring animal with a high frequency of CMI. We constructed a genealogy of more than 10,600 related CKCS dogs spanning 24 generations across 3 continents (North America, Australia, and Europe) from over 600 MRI confirmed dogs. A molecular genetic study of 173 CKCS dogs identified six chromosomal regions with potentionally significant results: chromosomes 3, 5, 9, 11, and 15. We are currently performing additional studies in additional dogs. Confirmed chromosomal regions will be further studied, with the aim of identifying the causative mutation(s) and gene(s). Identification of the CM/SM gene(s) will allow the development of a genetic test for the identification of carriers for breeding purposes with the ultimate aim of reducing or eliminating this devastating condition in the CKCS breed."
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October 2007: Alternatives to MRI Scans: Dr. Curtis W. Dewey, board certified veterinary neurologist and board certified veterinary surgeon, Cornell University in Ithaca, New York, and Dr. Dominic J. Marino, board certified veterinary neuro-surgeon and chief of staff at Long Island Veterinary Specialists (LIVS) in Plainview, New York, Dr. Georgina Barone (board certified veterinary neurologist), and other specialists at LIVS also have been researching the possible use of the brain stem auditory evoked response (BAER) test, infrared thermography (IRT), and helical (spiral) computed tomography (CT), as screening tools for identifying adult CKCSs with CM. BAER is a clinical electro-diagnostic tool used to evaluate hearing ability as well as the functional integrity of the brain stem.In an October 2007 update, Dr. Marino reported that 38 Cavaliers had been evaluated thus far. Of those, one dog had a normal MRI, BAER, and thermographic evaluation; 23 dogs without clinical signs of SM had abnormal MRI findings, with 16 of those 23 dogs (69.6%) also having abnormalities with BAER testing; and 14 dogs with clinical signs of SM had abnormal MRI findings, and 13 of those 14 dogs (92.8%) also had abnormal BAER tests. He concluded that “BAER testing may play a more useful role in screening ‘clinical’ dogs rather than dogs without clinical signs.”
Dr. Marino also reported that each dog was imaged with thermography, both awake and under general anesthesia. He stated that the complete analysis of thermal patterns is on-going, but that preliminary results revealed “cooler” thermographic patterns in dogs with abnormal MRI findings compared with the one dog with a normal MRI. Magnetic resonance imaging findings were classified as mild, moderate, and severe correlated with thermographic findings, 100%, 50%, and 0% of the time respectively. Based on these very preliminary findings, Dr. Marino concluded in his October 2007 report that "thermography may be a viable imaging modality to use as a screening tool to detect CLM in dogs." Dr. Marino may be contacted at telephone 516-501-1700, email Bongorno@aol.com LIVS's website is www.LIVS.org.
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September 2007: Dr. Rusbridge's Syringomyelia News Autumn 2007 Research Update4
June 2007: Association between frontal-sinus size and SM: Dr. Dewey and others (Drs. Peter V. Scrivani, Margret S. Thompson, Kevin R. Winegardner, and Janet M. Scarlett) report in a June 2007 article of a study of 62 dogs (four of them were CKCSs) that there may be an association between frontal-sinus size and SM in Cavaliers and other small-breed dogs. They state:"Our data do suggest, however, that the pathogenesis of syringohydromyelia in small-breed dogs may involve the supratentorial portion of the cranial cavity. We postulate that syringohydromyelia develops in many small-breed dogs and certain breeds in particular as a result of global malformation of the entire cranial cavity or supratentorial portion of the cavity and is not limited to the infratentorial portion of the cranial cavity. If this is true and results can be generalized to the target population, our understanding of the pathogenesis of syringohydromyelia in small-breed dogs and several aspects of clinical management (e.g., screening and diagnostic testing, breeding recommendations for dogs with dome-shaped heads, and treatments) will require further investigation."
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May 2007: Study of possible correlation between head shape and CM/SM in Cavaliers and other toy breeds. Dr. Rusbridge and Ms. Knowler report in their April/May 2007 Research Newsletter the the preliminary results of pilot study looking at the possible correlation between head shape and CM/SM in different toy breeds. They report:"In response to some observations made by breeders on head shape, a simple pilot study was devised. Dogs were selected on the basis of head length/breadth ratio, degree of doming, and presence or absence of a ski-slope shape to the back of the head. CM/SM status was confirmed by MRI. Early results of this pilot study found no correlation, however the investigation is still ongoing. This study has been a tremendously valuable exercise in other ways. On the basis of head shape, some dogs had been presumed to be affected, and owners had originally elected against MRI screening. However some of these dogs were actually found to be free of the condition. This suggests that it is not yet possible to predict CM/SM by a visual assessment of head shape. It also provided the opportunity to obtain blood DNA samples for the Genome study in Montreal. In particular, we would like to thank Lee Pieterse for co-ordinating the project in Australia. She and her husband Frank also contributed $4000 towards the research. Sandy Smith in Canada, generously donated $8000 from the ‘For the Love of Ollie’ Fund. An additional sum of $4000 came from the ‘Syringomyelia DNA Research’ Fund. Total $16,000." Donate to For the love of Ollie or directly to SM DNA Research
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Dr. Rusbridge's Syringomyelia News 2007 Research Update4
Geneticist to Research SM Breeding Protocol: Dr. Rusbridge and Ms. Knowler report in their Syringomyelia News 2007 Research Update that Dr. Sarah Blott MSc PhD of the Genetics Department at the Animal Health Trust has joined the CM/SM research team. Dr. Blott is a geneticist with a particular interest in developing breeding schemes for companion animals. She combines state-of-the-art knowledge in quantitative genetics with molecular genetic markers.4
June 2007: Development of Clinical Signs and CSF Flow: Dr. Natasha J. Olby, board certified veterinary neurologist, and Dr. Sofia Cerda-Gonzalez, both at North Carolina State University's College of Veterinary Medicine's Department of Clinical Sciences, reported in June 2006 that they and team members at IAMS Pet Imaging Center, Raleigh, NC. are in the process of conducting a three year study to determine whether abnormalities of the caudal fossa and cervical spine predict future development of clinical signs of SM.The NC State/IAMS Pet Imaging Center team also has been studying the dynamics of cerebrospinal fluid flow in Cavalier King Charles Spaniels, and the extent to which head positions of the dogs affect the flow patterns. They reported in June 2006 finding that turbulent flow occurs in dogs with SM and can be found within syrinxes, and that CSF flow velocity may be higher within the dorsal subarachnoid space of affected dogs. They stated that additional studies are needed to determine whether their findings are significant. For more information, go to http://www.cvm.ncsu.edu/docs/neuro_studies.html or contact Dr. Cerda-Gonzalez at scerdag@ncsu.edu.
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Progression of SM as Puppies Grow: Dr. Curtis W. Dewey, board certified veterinary neurologist and board certified veterinary surgeon, Cornell University in Ithaca, New York, is planning to begin a project of repeated MRI scanning of litters of Cavalier King Charles spaniel puppies to identify the prevalence of Chiari-like malformation in the breed, and its progression as the puppies grow. For more information, contact Dr. Dewey at cwd27@cornell.edu4
April 2006: Full Genome Scan & Genetic Mapping: Dr. Rusbridge and Ms. Knowler reported in August 2005 that their study of Cavalier King Charles spaniels diagnosed with syringomyelia has shown that the disease is a common condition in Cavaliers and appears to be more severe and have an earlier onset with increased inbreeding, especially when breeding from affected dogs. They have been leading a successful effort to collect DNA from thousands of Cavaliers from throughout the world, to conduct a survey to identify DNA markers. In an April 2006 research update, Dr. Rusbridge reports that "a full genome scan looking for the causal gene/s of syringomyelia and mitral valve disease is underway!" (A Dr. Clare Rusbridge video DVD "Syringomyelia Seminar" is available by contacting penny.knowler@ntlworld.com ). The Cavalier Health Foundation (associated with the Cavalier King Charles Spaniel Club, USA) has contributed a grant to help underwrite this project. Donate to the Cavalier Health Foundation and For the love of Ollie or directly to SM DNA Research!Also participating are Marie Pierre Dube, a genetics epidemiologist at the Montreal Heart Institute, and Dr. Zoha Kibar, the molecular geneticist in charge of fine mapping and identification of the gene(s) defective in SM in CKCSs, at the Centre for the Study of Brain Diseases, CHUM – Montreal. The study is searching for recessive genes which may be the cause of the disease. The researchers suspect that the disorder is not due to a simple recessive gene, but rather a complex trait. Their future plans include genotyping, linkage disequilibrium analysis gene mapping, and positional candidate gene cloning. Dr. Kibar commented about her current gene study, as follows:
"Breeders should understand that our study will not be the magic solution that will help them identify dogs that will not develop SM for breeding purposes (at least not in the short term). But identifying a gene will open the door to understanding pathways involved in the development of this disease and hopefully in the long run, a cure for these suffering dogs. Of course we are also interested in the biology. Irrespective of the complexity we are dealing with, we have to try to understand the disease with the tools we have and hence the genetic approach. And irrespective of this complexity, and if we don’t want to think about the multifactorial etiology, the breeding protocol scheme Dr. Rusbridge came up with is the best solution for now. Then later we can deal with the causes."
In the April 2006 update, Dr. Kibar reports:
"Both Syringomyelia and Mitral valve disease are particularly common in the Cavaliers. Such high incidence in a particular breed as compared to other breeds suggests the involvement of genetic factors. The mode of inheritance including the number, identity and relative contribution of the causative genes is not determined yet. The etiology of both conditions could be further complicated by variable penetrance of the various genotypes and the involvement of environmental factors.
"The first step which is genetic mapping is currently underway. Due to the complex inbreeding in the CKCS, a preliminary genetic analysis was necessary to evaluate the informativeness of the genetic markers and hence the feasibility of a whole genome scan in such breed. Consequently, 10 dogs were selected for genotyping with 122 markers distributed among the 38 autosomes and X chromosome. The markers were found to be sufficiently polymorphic and informative. Next, 200 dogs were selected for a whole genome scan, primarily for Chiari malformation. However with additional phenotypic information on mitral valve disease, it is possible to use the same data to map the gene(s) defective in this disease. The whole genome scan was conducted at the Mammalian genotyping Center [Center for Medical Genetics] at the Marshfield Clinic in Wisconsin, USA. The genotyping data will now be analyzed using both linkage-based and association studies. In the latter, we will be taking advantage of the founder effect demonstrated for both these disorders in the CKCS breed.
"This strategy involves: 1) genetic mapping of the underlying gene(s), 2) identification of these defective gene(s) using the positional candidate gene approach and characterization of the mutation(s) and 3) initial functional characterization of the protein(s) encoded by the gene(s). This will help better understand the underlying pathogenic mechanisms for better diagnosis, prognosis and clinical management of these devastating conditions. These studies will also help unravel some of the complexity involved in this malformation in humans and in the embryonic development of the affected structures."
Canadian physicians and researchers Dr. Guy A. Rouleau, at McGill University, and Dr. Berge Minassian, at the University of Toronto also are participating in this research. Drs. Rouleau's and Minassian's experience includes having isolated the canine gene deemed responsible for Lafora's disease, a form of epilepsy. Dr. Clare Rusbridge and Penny Knowler may be reached at Stone Lion Veterinary Centre, 41 High Street, Wimbledon, London, SW19 5AU, telephone 0208 946 4228, email Dr. Rusbridge neuro.vet@btinternet.com email Ms. Knowler penny.knowler@ntlworld.com
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April 2006: Positioning for MRIs: In April 2006, the Cavalier King Charles Spaniel Club, UK announced that it will be funding research into whether the positioning of the dog's head in the MRI's receiving coil influences the accuracy of the resulting MRI scan of the dog's brain and spinal canal. Dr. Rusbridge and Dr. Nick Jeffery, BVSc PhD CertSAO DSAS (soft tissue) DECVN DECVS FRCVS, at the University of Cambridge's Department of Veterinary Medicine, in Cambridge, England will be conducting this project. This research is expected to lead to greater accuracy and uniformity in MRI scans of dogs with CM and SM. For more information, contact Dr. Rusbridge at Stone Lion Veterinary Centre, 41 High Street, Wimbledon, SW19 5AU, telephone: 00 44 208 9464228, email neuro.vet@btinternet.com or Dr. Jeffery at telephone 01223 337621, email ndj1000@cam.ac.uk (April 2006)4
March 2006: Repeated MRIs Study: In March 2006, the Cavalier King Charles Spaniel Club of Canada (CKCSCC) announced plans for a syringomyelia research project to be conducted by Dr. Roberto Poma, DMV, DVSc, ACVIM Neurology, Assistant Professor, Department of Clinical Studies, Ontario Veterinary College. Participating Cavalier King Charles Spaniels first will undergo a preliminary examination, including blood work, by Dr. Poma to determine eligibility for the project. Once accepted, the dogs will have MRIs at a cost of about $600.00 (Canadian). The preferred age of participating Cavaliers is as young as 5 1/2 months. A second evaluation will be conducted 3.5 years. However, depending on the findings of the first MRI, the dog may be examined again at 1.5 years and then again at 3.5 years. As group of older dogs, over age 3.5 years, also may be included, with their data collected as a subset grouping. Anyone interested in having their Cavaliers participate in this program should contact Pat Barrington of the CKCSCC's Health & Education Committee to receive a questionnaire or for more information. Her email address is harley2@sympatico.ca4
2005 Ultrasound As SM Detector: Drs. Dominik Faissler and John McDonnell, board certified veterinary neurologists at the Cummings School of Veterinary Medicine at Tufts University in Massachusetts, are researching the use of ultrasonography to diagnose syringohydromyelia in dogs. In a 2005 interim report, the researchers stated, "This preliminary study indicates that cervical spinal cord ultrasound can be useful as a diagnostic aid for CM. It cannot rule out a diagnosis of CM, however no false positives were found. To investigate the sensitivity and specificity of this imaging modality blinded U/S examination of large numbers of dogs after MRI evaluation is planned."4
Post-mortem studies of Cavaliers: Owners of deceased Cavalier King Charles spaniels, which had been diagnosed with syringomyelia or Chiari-like malformation are urged to donate their dogs' bodies to researchers for post-mortem studies to enable the designing of a protocol for dealing with pathological material. Any owners interested in contributing their late Cavaliers to SM research should contact any of these researchers: Dr. Nick Jeffery, Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 OES, telephone 01223 337621, email ndj1000@cam.ac.uk; Dr. Jim Anderson, Glasgow University, email Gvsa07@udcf.gla.ac.uk; Dr. Rodolfo Cappello, The Royal Veterinary College, University of London, email RCappello@RVC.AC.UK; or Dr. Curtis Dewey, Cornell University, email cwd27@cornell.edu The nervous system degenerates rapidly after death and must be handled appropriately, so please contact these researchers as soon as or ideally before the dog has been euthanatized.Syringomyelia Seminars
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International Symposium on Syringomyelia held October 23, 24, 25, 2007 in Rugby UK, sponsored by The Ann Conroy Trust, with the University of Birmingham, the Society of British Neurological Surgeons, and the Spine Society of Europe. Speakers were Clare Rusbridge, Dominic Marino, Graham Flint, Guy Rouleau, and Sarah Blott. Obtain compact discs of all five talks and the hour long Q&A session with leading experts on syringomyelia and the Chiari-like malformation in cavaliers, for a contribution to support CKCS genome research at http://www.cafepress.com/cavaliertalk/43114564
Syringomyelia International Conference held November 11, 2006 at the Royal Veterinary College: Read summaries of presentations by Clare Rusbridge, Paul Mandigers, Laurent Cauzinille, Harvey Carruthers, Nick D. Jeffery, Catherine A. Loughin, Martin Deutschland, Dominic J. Marino, and G. Flint, and view their slide presentations.Breeders' Responsibilities
SM has a tendency to be more severe in each subsequent generation, and with an earlier onset. Breeders should follow the SM Breeding Protocol
.What You Can Do
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Donate by buying For the love of Ollie.4
Participate in the Syringomyelia Cavalier Collection Scheme. Read about it here.4
Donate funds to Cavalier SM DNA research; payee "Syringomyelia DNA Research", address: Stone Lion Veterinary Hospital, Goddard Veterinary Group, 41 High Street Wimbledon Common London SW19 5AU, email CRusbridge@goddardvetgroup.co.uk, telephone: 020 8946 4228, fax: 020 8944 0871. Read about it here.4
Donate to Rupert's Fund, which pays for MRIs of older dogs, to aid the Syringomyelia Genome Research Project.4
Send MRI scans of Cavaliers 5 years old or older and which do not have SM, along with MRIs of those dogs' family members, to Dr. Clare Rusbridge at neuro.vet@btinternet.com Read about it here.4
Contact Sheena Stevens in Devon, UK, telephone 01884 821080, email Kilnshena@hotmail.com, about sending aborted Cavalier fetuses and deceased young puppies (that have died for any reason) to Dr. Imelda McGonnell at The Royal Veterinary College for research. Read about it here.Related Links
SM Breeding Protocol
Board Certified Veterinary Neurologists
MRI Screening Protocol
Estimated Breeding Values
Cerebellar Infarcts
Primary Secretory Otitis Media (PSOM)
Questions for Cavalier Breeders
Canine Health Testing Clinics
Dr. Clare Rusbridge:
Dr.
Rusbridge's Comprehensive Website
Rusbridge/Knowler 2010 Research into CM Report
Dr. Rusbridge's Syringomyelia News Winter 2007 Research Update
Dr. Rusbridge's Syringomyelia News Autumn 2007 Research Update
Dr. Rusbridge's Syringomyelia News 2007 Research Update
Dr. Clare Rusbridge video DVD "Syringomyelia Seminar", contact penny.knowler@ntlworld.com
A website devoted to syringomyelia in Cavaliers is Karlin Lillington's SM.CavalierTalk.com
Margaret Carter's "About SM" webpage
Two SM support email groups for owners of dogs with SM are
Yahoo! Group:
Arnold Chiari Dogs
and
Yahoo! Group:
CKCS SM-support
Two SM email discussion groups are
Yahoo! Group: CKCS-SM
and Karlin Lillington's
CavalierTalk: SM
and MVD Cavaliers Forum.
A website and a book about a Cavalier diagnosed with syringomyelia is at For the love of Ollie.
UK Cavalier Club's List of MRI Scanned USA Cavalier Breeding Stock
Cavalier Owners' Blogs:
All about Minnie
(Moo)
Ella's
Battle With Syringomyelia
Riley's Beating
Syringomyelia
Abbey our
CKCS and her family's Syringomyelia Journey
Lucy Magic Sky
Brussels Griffon Owner's Blog:
Friends of Lola
Webpages from Laura Lang's
CKCS Info Center website,
showing additional MRIs
and x-rays of SM-affected or CM Cavaliers:
MRI image primer
MRI
images of Cavaliers diagnosed with and without the malformation and SM
For answers to frequently asked questions about MRIs and what to expect if your dog is to undergo one, see PetsDx - Pet Owners Frequently Asked Questions
SM in Other Breeds
Other breeds known to be affected by Chiari-like malformation and syringomyelia include the Affenpinscher, Bichon Frisé, Boston terrier, Brussels Griffon (Griffon Bruxellois), bull terrier, Chihuahua, French bulldog, Havanese, King Charles spaniel (the English toy spaniel), Maltese terrier, miniature dachshunds, miniature and toy poodles, Papillon, Pomeranian, Pugs, Shih Tzu, Staffordshire bull terrier, and the Yorkshire terrier. Click on their hyperlinked names to link to Internet articles about CM and SM in those breeds.
Veterinary Resources
Mechanism of the decrease in intracranial pressure as affected by furosemide. Pinegin LE, Dolzhenko DA, Natochin IuV. Biull Eksp Biol Med 1984;98:682–685.
Furosemide lowers intracranial pressure by inhibiting CSF production. Lorenzo AV, Hornig G, Zavala LM, et al. Z Kinderchir 1986;41(Suppl 1):10–12.
Dorsal notch of foramen magnum due to incomplete ossification of supraoccipital bone in dogs. Watson, A.G., De Lahunta, A., and Evans, H.E. J. Small Anim. Prac. 1989 30:666-673.
Effect of histamine H2 receptor antagonists on the secretion of cerebrospinal fluid in the cat. Naveh Y, Kitzes R, Lemberger A, Ben-David S, Feinsod M. J Neurochem. 1992 Apr;58(4):1347-52.
Occipital dysplasia and associated cranial spinal cord abnormalities in two dogs. Rodney S. Bagley, Michael L. Harrington, Russell L. Tucker, Ronald D. Sande, Charles R. Root, Robert W. Kramer. Vet. Rad. & Ultra. Sept 1996; 37(5): 359.
Persistent scratching in Cavalier King Charles spaniels. Rusbridge C. Vet Rec. Aug 1997;141(7):179.
Different effects of omeprazole and Sch 28080 on canine cerebrospinal fluid production. Javaheri S., Corbett W. S., Simbartl L. A., Mehta S., Khosla A. Brain Research 1997; 754(1-2); 321-324. Quote: "We investigated the effects of omeprazole and Sch 28080, a more specific and a more potent inhibitor of K+,H+-ATPase than omeprazole, in canine cerebrospinal fluid (CSF) production. ... [T]he percent decreases in CSF production in the omeprazole treated group were ... significantly more than the respective values in the control group. ... We conclude that in the canine model, physiological doses of omeprazole decrease CSF production by about 26. However, the effect is independent of the K+,H+-ATPase activity, since Sch 28080 which is more potent than omeprazole did not significantly affect CSF production."
A syndrome of syringomyelia in the cavalier King Charles spaniel, and its treatment by syringo-subarachnoid shunting. Skerritt GC, Hughes D: In Proceedings from the 12th Annual Symposium of the European Society of Veterinary Neurology, Vienna, 23: 1998.
Syringohydromyelia in Cavalier King Charles spaniels. Rusbridge C, MacSweeny JE, Davies JV, Chandler K, Fitzmaurice SN, Dennis R, Cappello R, Wheeler SJ. J Am Anim Hosp Assoc. 2000 Jan-Feb;36(1):34-41.
Chiari 1/syringomyelia complex in a King Charles Spaniel. Churcher RK, Child G. Aust Vet J. 2000 Feb;78(2):92-5. Quote: "A 9-year-old King Charles Spaniel presented with a history of progressive forelimb weakness and paroxysmal involuntary flank scratching over a 2-year period. Neurological examination suggested a myelopathy of C1 to C4 spinal cord segments. Advanced imaging studies revealed hydrocephalus, caudal herniation of part of the caudal lobe of the cerebellum through the foramen magnum and marked syrinx formation to the level of the caudal thoracic spine, resembling Arnold-Chiari malformation with secondary hydromyelia in humans. Mechanical obstruction at the craniocervical junction, altering CSF flow dynamics, may lead to syrinx formation. Response to diuretic therapy was moderate but surgical decompression may offer better long term prognosis."
Dorsal dens angulation and a Chiari type malformation in a Cavalier King Charles Spaniel. Bynevelt M, Rusbridge C, Britton J. Vet Radiol Ultrasound. 2000 Nov-Dec;41(6):521-4.
Primary secretory otitis media in the Cavalier King Charles spaniel: a review of 61 cases. Stern-Bertholtz W.; Sjöström L.; Wallin Håkanson N. J Small Anim. Prac., June 2003, 44(6): 253-256(4).
Hereditary aspects of occipital bone hypoplasia and syringomyelia (Chiari type I malformation) in cavalier King Charles spaniels. Rusbridge C, Knowler SP. Vet Rec. Jul 2003;153(4):107-12.
Neurological signs and results of magnetic resonance imaging in 40 cavalier King Charles spaniels with Chiari type 1-like malformations. Lu D, Lamb CR, Pfeiffer DU, Targett MP. Vet Rec. Aug 2003;153(9):260-3.
Suboccipital Craniectomy and Cranial Dorsal Laminectomy as a Treatment Option for Chiari Type I Malformation Malformation In the Cavalier King Charles Spaniel. K. Vermeersch; L. Van Ham; J. Caemaert; M. Tshamala; O. Taeymans; S. Bhatti; I. Polis1. ESVN 2003 Symposium Abstract 14, J.Vet.Int.Med. 19(2). Quote: "Syringohydromyelia combined with cerebellar tonsil herniation, known as Chiari type I malformation (CIM) is known to occur in Cavalier King Charles spaniels in many countries. The dogs either have progressive cranial (eg, facial deficits, seizures, vestibular syndrome) or spinal (eg, hyperesthesia with persistent scratching of shoulder and neck region) symptoms. Diagnosis is best made by magnetic resonance imaging (MRI): fluid-filled cavity within the spinal cord and cerebellar tonsil herniation. As therapeutic options medical treatment with corticosteroids, acetazolamide, NSAIDs or oral opioids may give an improvement but most often not a resolution of signs. It is thought that syrinx formation in humans and dogs with CIM occurs secondary to partial obstruction of CSF flow at the cranio-cervical junction. Therefore, in human medicine, a suboccipital craniectomy and cranial dorsal laminectomy with opening of the dura mater is the procedure of choice for surgical treatment of CIM. This surgical technique was performed on 4 Cavalier King Charles spaniels diagnosed with Chiari type I malformation by symptoms (scratching of neck region) and by MRI. The dogs were evaluated neurologically 24 hours, 1 month and 3 months postoperatively. Control MRI took place 3 months postoperatively. Three dogs recovered uneventfully from anesthesia. The fourth dog was euthanized within 24 hours after surgery at owners request due to progressive seizures and decreased capability of oxygen saturation. Neurologically, the 3 dogs did worse 24 hours after surgery (neck pain, neck weakness and head tilt), improved gradually and by 3 months postoperatively, achieved the same neurological state as before surgery. Control MRI of the 3 dogs at that time showed no regression of syrinx size. The results of this study indicate that there is no improvement on short term basis in either syrinx size or clinical symptoms after surgical intervention with a suboccipital craniectomy and cranial dorsal laminectomy with opening of the dura. Seen the progressive nature of the disorder, follow-up over a longer period of time is necessary to see if this surgical technique may influence the progression of syrinx formation and clinical signs in Cavalier King Charles spaniels with Chiari type I malformation."
Sound Wave Therapy Not So Shocking. Kate Chope, José M. García-López. Tufts Vety School, Dec 2003 Case Report. http://www.tufts.edu/vet/vet_common/pdf/petinfo/dvm/case_dec2003.pdf
Caudal occipital malformation syndrome in dogs. Dewey CW, Berg JM, Stefanacci JD, et al. Compend. Contin. Educ. Pract. Vet. 2004:26:886-896.
Gabapentin is a first line drug for the treatment of neuropathic pain in spinal cord injury. Levendoglu F, Ogun CO, Ozerbil O, et al. Spine 2004;29:743–751.
Suboccipital craniectomy, dorsal laminectomy of C1, durotomy and dural graft placement as a treatment for syringohydromyelia with cerebellar tonsil herniation in Cavalier King Charles spaniels. Vermeersch K, Van Ham L, Caemaert J, Tshamala M, Taeymans O, Bhatti S, Polis I. Vet Surg. 2004 Jul-Aug;33(4):355-60. Quote: "Objective— To evaluate retrospectively the efficacy of the suboccipital craniectomy and dorsal laminectomy of C1 with durotomy and placement of a dural graft for treatment of syringohydromyelia (SHM) because of cerebellar tonsil herniation in Cavalier King Charles spaniels (CKCS). This technique is used with great success in human medicine. Study Design— Four CKCS diagnosed by Magnetic resonance imaging (MRI) of SHM because of cerebellar tonsil herniation and not responsive to medical therapy underwent a suboccipital craniectomy and dorsal laminectomy of C1 (2 dogs) and of C1 and partial C2 (2 dogs) with durotomy and placement of a dural graft. Three dogs were evaluated neurologically 24 hours, 1 month, and 3 months postoperatively and evaluations were compared with preoperative neurological examination. Repeat MRI took place 3 months postoperatively. Results— Neurological examinations showed neither improvement nor progression of clinical signs 3 months postoperatively. MRI showed no regression of syrinx size 3 months postoperatively. Conclusion— Improvement was not seen. Given the progressive nature of the disorder, evaluation over a longer period of time is necessary to detect if progression has stopped. Some modification to the surgical technique is needed to accomplish the same results as in human medicine. A study of a larger population is needed to attain more reliable information. Clinical Relevance— Suboccipital craniectomy and dorsal laminectomy of C1 with durotomy and placement of a dural graft is a feasible technique in CKCS, but needs some modification to accomplish the same results as in human medicine."
Inheritance of occipital bone hypoplasia (Chiari type I malformation) in Cavalier King Charles Spaniels. Rusbridge C, Knowler SP. J Vet Intern Med. 2004 Sep-Oct;18(5):673-8.
Hindbrain decompression in a dog with scoliosis associated with syringomyelia. Takagi S, Kadosawa T, Ohsaki T, Hoshino Y, Okumura M, Fujinaga T. JAVMA, 2005 Apr.; 226 (8).
Neurological diseases of the Cavalier King Charles spaniel. Rusbridge, C. J. Small Anim. Prac., June 2005, 46(6): 265-272.
Treatment of Caudal Occipital Malformation Syndrome in Dogs by Foramen Magnum Decompression. CW Dewey, JM Berg, G Barone, DJ Marino, JD Stefanacci. J Vet Intern Med; May/June 2005;19(3) (ACVIM 23rd Ann. Vet. Med. Forum Abstract Program: Abstract 71).
CSF flow abnormalities in caudal occipital malformation syndrome. PA March, CJ Abramson, M Smith, and J Murakami. J Vet Intern Med 2005;19:418 (ACVIM 23rd Annual Veterinary Medical Forum Abstract Program: Abstract 72).
The Use of Ultrasonography to Diagnose “Caudal Occipital Malformation Syndrome” in Dogs – a Prospective Study in 12 Dogs. B Levitin, JJ McDonnell, D Faissler, AS Tidwell. J Vet Intern Med; May/June 2005;19(3) (ACVIM 23rd Ann. Vet. Med. Forum Abstract Program: Abstract 209).
Inherited Occipital Hypoplasia/Syringomyelia in the Cavalier King Charles Spaniel: Experiences in Setting Up a Worldwide DNA Collection. Rusbridge C., Knowler P., Rouleau G. A., Minassian B. A., and Rothuizen J. J.Heredity, Jun 2005; 10:1093.
Surgical Management of Combined Hydrocephalus, Syringohydromyelia, and Ventricular Cyst in a Dog. Hasegawa T., Taura Y., Kido H., Shibazaki, and Katamoto H. J. Am. Anim. Hosp. Assoc., July/August 2005; 41: 267 - 272.
Foramen magnum decompression for treatment of caudal occipital malformation syndrome in dogs. Dewey C.W., Berg J.M., Barone G., Marino D.J., and Stefanacci J.D. JAVMA, Oct. 2005 ; 227 (8): 1270-1275.
Syringomyelia and genetic challenges [in Cavalier King Charles Spaniels]. Dunn, T.J., Jr. Dog World, Apr. 2006; 91(4): 14-15.
Bakre skallgropens form hos hund: en studie av occipital hypoplasi hos hund. Spångberg, Camilla. Dept. of Small Animal Clinical Sciences, Swedish University of Agricultural Sciences. Examensarbete (Sveriges lantbruksuniversitet, Fakulteten för veterinärmedicin och husdjursvetenskap, Veterinärprogrammet) vol. 2006:51. Quote: "The aim of the study was to examine whether there is a difference in the shape of the caudal fossa between CKCS, small bred dogs with a similar head shape and dogs with a normal head shape and if occipital bone hypoplasia is related to a head shape with a steep back of the head. Other aims of the study were to examine the crowding of nervous tissue in the foramen magnum in each breed group, the extent of syringohydromyelia and to what extent the malformation had caused neurological signs. ... This study showed that there is a difference in the shape of the caudal fossa between dogs with a normal head shape and small bred dogs with a steep back of the head. This indicates that occipital bone hypoplasia is related to a head shape where the back of the head is steep and that the malformation is common in these breeds. The study also showed that occipital bone hypoplasia not inevitably causes syringohydromyelia. Only one of the dogs with occipital bone hypoplasia or possible bone hypoplasia had had neurological signs that with certainty were related to the malformation. This result gives further support to previous studies that have stated that occipital bone hypoplasia occurs asymptomatic." http://exepsilon.slu.se/archive/00000866/
Syringomyelia: Current Concepts in Pathogenesis, Diagnosis, and Treatment. Clare Rusbridge, Dan Greitz, and Bermans J. Iskandar. J Vet Intern Med; May/June 2006;20(3):469–479. Quote: "Syringomyelia is a condition that results in fluid-containing cavities within the parenchyma of the spinal cord as a consequence of altered cerebrospinal fluid dynamics. This review discusses the history and the classification of the disorder, the current theories of pathogenesis, and the advanced imaging modalities used in the diagnosis. The intramedullary pulse pressure theory (a new pathophysiologic concept of syringomyelia) also is presented. In addition, the current understanding of the painful nature of this condition is discussed and the current trends in medical and surgical management are reviewed."
Morphology of the Caudal Fossa in Cavalier King Charles Spaniels. S Cerda-Gonzalez, NJ Olby, TP Pease,S McCullough, N Massoud, R Broadstone. J Vet Intern Med; May/June 2006;20(3) (ACVIM 24th Ann. Vet. Med. Forum Abstract Program: Abstract 95); Vet. Radiology & Ultrasound, Jan/Feb 2009;50(1):37-46.
Characteristics of Cerebrospinal Fluid Flow in Cavalier King Charles Spaniels. S Cerda-Gonzalez, NJ Olby, TP Pease,S McCullough, N Massoud, R Broadstone. J Vet Intern Med; May/June 2006;20 (ACVIM 24th Ann. Vet. Med. Forum Abstract Program: Abstract 96).
Foramen Magnum Decompression with Cranioplasty for Treatment of Caudal Occipital Malformation Syndrome in Dogs. CW Dewey, KS Bailey, DJ Marino, G Barone, P Bolognese, TH Milhorat, DJ Poppe. J Vet Intern Med; May/June 2006;20(3) (ACVIM 24th Ann. Vet. Med. Forum Abstract Program: Abstract 267).
Brain Stem Auditory Evoked Response (BAER) Testing in Cavalier King Charles Spaniels with Caudal Occipital Malformation Syndrome. CW Dewey, KS Bailey, G Barone, J Stefanacci. J Vet Intern Med; May/June 2006;20(3) (ACVIM 24th Ann. Vet. Med. Forum Abstract Program: Abstract 270).
Intracranial Epidermoid Cyst and Syringohydromyelia in a Dog. Edward Mackillop, Scott J. Schatzberg, Alexander De Lahunta. Vet. Rad. & Ultra. July-Aug. 2006; 47:339.
Syringomyelia in Cavaliers. Bruce Fogle. Dogs Today, Aug 2006, pg. 56.
Association Between Spinal Cord Dorsal Involvement and Pain in Syringomyelia Secondary to Canine Chiari Malformation. C Rusbridge. H. Caruthers, Marie-Pierre Dube´, M Holmes, N.D. Jeffery. 2006 ESVN Symposium, Abstract #13. J.Vet.Intern.Med. 21(5). Quote: "This study was designed to test the hypothesis that pain associated with syringomyelia in dogs is related to spinal cord dorsal horn damage. Syrinx dimensions and precise location within the spinal cord were determined by masked observers from magnetic resonance images of 55 cavalier King Charles spaniels (CKCS) with syringomyelia. After removal of masking, syrinx parameters were compared between the cohort of dogs that exhibited pain with those that did not. Maximum syrinx width was the strongest predictor of pain in dogs with syringomyelia. Syrinx width was also correlated with scratching behaviour and scoliosis. Syrinx width was strongly correlated with dorsal horn involvement. Dogs with pain were also more likely to have extensive dorsal grey column damage. Large syrinxes with dorsal horn damage are associated with persistent pain which may have implications for the success of surgical and medical management. Our results suggest that the pain behaviour expressed by this group of patients is likely to be ‘neuropathic pain’, resulting from disordered neural processing in the damaged dorsal horn. As such it is likely that conventional analgesic medication may be ineffective."
Coexistence of occipital dysplasia and occipital hypoplasia/syringomyelia in the cavalier King Charles spaniel. C. Rusbridge and S. P. Knowler. J. Small Anim. Prac. Oct. 2006, 47(10):603-606. Quote: "Concurrent occurrence of occipital dysplasia and occipital hypoplasia in two dogs is described in this report. Occipital hypoplasia results in reduced volume of the caudal fossa, leading to overcrowding of the neural structures and, in severe cases, development of syringomyelia. In occipital dysplasia, there is a failure of complete ossification of the supraoccipital bone. When the two conditions occur concurrently, it is possible that syringomyelia may develop more slowly, resulting in presentation with clinical signs in middle to old age. This has implications for screening tests for early detection of syringomyelia, with a view to using the dog for breeding purposes, as dogs with an apparently mild phenotype for occipital hypoplasia/syringomyelia may actually have a more severe genotype. ... [On post-mortem examination of CKCS and other small breed dogs that the supraoccipital bone overlying the cerebellar vermis is remarkably thin and sometimes eroded so that the foramen magnum is enlarged dorsally]."
Chiari-like malformation and Syringomyelia in the Cavalier King Charles Spaniel. Clare Rusbridge. PhD. thesis. Utrecht University, Utrecht, The Netherlands. 2007.
Pathophysiology and treatment of neuropathic pain associated with syringomyelia. Clare Rusbridge, Nick D. Jeffery. Vet.J. 2007 Feb 19. Quote: "The pain behaviour expressed by dogs with syringomyelia suggests that they experience neuropathic pain, probably due to disordered neural processing in the damaged dorsal horn. As such it is likely that conventional analgesic medication will be ineffective. In this review, physiological and pathological pain processing through the dorsal horn is summarised and mechanisms by which syringomyelia could result in a persistent pain state are discussed. Finally, current knowledge regarding treatment of Chiari malformation and syringomyelia is reviewed and possible drugs which may give improved pain relief in affected dogs are discussed."
New name agreed as international attention focuses on syringomyelia. Clare Rusbridge. Veterinary Times. Apr. 2007.
Association between frontal-sinus size and syringohydromyelia in small-breed dogs. Peter V. Scrivani, Margret S. Thompson, Kevin R. Winegardner, Curtis W. Dewey, Janet M. Scarlett. Am. J. Vet. Research, June 2007, Vol. 68, No. 6, Pages 610-613. Quote: "Our data do suggest, however, that the pathogenesis of syringohydromyelia in small-breed dogs may involve the supratentorial portion of the cranial cavity. We postulate that syringohydromyelia develops in many small-breed dogs and certain breeds in particular as a result of global malformation of the entire cranial cavity or supratentorial portion of the cavity and is not limited to the infratentorial portion of the cranial cavity. If this is true and results can be generalized to the target population, our understanding of the pathogenesis of syringohydromyelia in small-breed dogs and several aspects of clinical management (e.g., screening and diagnostic testing, breeding recommendations for dogs with dome-shaped heads, and treatments) will require further investigation."
Chiari-Like Malformation with Syringomyelia in the Cavalier King Charles Spaniel: Long-Term Outcome After Surgical Management. Clare Rusbridge. Veterinary Surgery 2007 Jul;36(5):396-405. "Cranial cervical decompression surgery is associated with low mortality and morbidity, and results in clinical improvement in most dogs. The procedure seemingly does not result in syrinx collapse and resolution. Clinical improvement may not be sustained and some dogs can be expected to deteriorate."
Report from the Chiari-Like Malformation and Syringomyelia Working Group Round Table. Rodolfo Cappello, organizer, Clare Rusbridge, chairman. Veterinary Surgery 2007 Jul;36 (5), 509–512.
Foramen Magnum Decompression with Cranioplasty for Treatment of Caudal Occipital Malformation Syndrome in Dogs. Curtis W. Dewey, Dominic J. Marino, Kerry S. Bailey, Catherine A. Loughin, Georgina Barone, Paolo Bolognese, Thomas H. Milhorat, Dorothy J. Poppe. Veterinary Surgery 2007 Jul;36 (5), 406–415. "Foramen Magnum Decompression (FMD) with cranioplasty was well tolerated, with no intraoperative complications, and minor postoperative complications. Most dogs improved clinically, and none required further surgery at the original FMD site."
It's Time. Richard A. LeCouteur. Veterinary Surgery 2007 Jul;36 (5), 390–395. "Medical history is replete with examples of invasive procedures and pharmacologic interventions that were widely accepted based on results of case studies, only to later be rejected based on results of controlled clinical trials. ... It’s time to adopt a more structured scientific approach to the study of the management of neurologic conditions that may benefit from surgical intervention. The randomized (preferably) double-blinded (preferably) placebo-controlled study is the gold standard for evaluating a new treatment intervention."
Syringomyelia in cavalier King Charles spaniels: the relationship between syrinx dimensions and pain. C Rusbridge, H Carruthers, M-P Dubé, M Holmes, N D Jeffery. J Small Anim. Pract. 2007 Aug;48(8):432-6. Quote: "Objectives: This study was designed to test the hypothesis that pain associated with syringomyelia in dogs is dependent upon size and involvement of the dorsal part of the spinal cord. Methods: Masked observers determined syrinx dimensions and precise location within the spinal cord on magnetic resonance images of 55 cavalier King Charles spaniels with syringomyelia. After removal of masking, syrinx size and location were compared between the cohorts of dogs that exhibited pain with those that did not. Results: Maximum syrinx width was the strongest predictor of pain, scratching behaviour and scoliosis in dogs with syringomyelia. Both pain and syrinx size were positively correlated with syrinxes located in the dorsal half of the spinal cord. Clinical Significance: Large syrinxes associated with damage to the dorsal part of the spinal cord are associated with persistent pain suggesting that the pain behaviour expressed by this group of patients is likely to be 'neuropathic pain', resulting from disordered neural processing in the damaged dorsal horn. As such it is likely that conventional analgesic medication may be ineffective."
Radiographic morphology of the cranial portion of the cervical vertebral column in Cavalier King Charles Spaniels and its relationship to syringomyelia. Catherine E. Stalin, Clare Rusbridge, Nicolas Granger, and Nick D. Jeffery.. Am J Vet Res. 2008 Jan;69(1): 89-93. Quote: "Results suggested that radiographic morphology of the atlantoaxial region in CKCSs differs from morphology of that region in dogs of other breeds, but that these differences do not account for why some CKCSs develop syringomyelia and others do not."
Pathophysiology and treatment of neuropathic pain associated with syringomyelia. Clare Rusbridge and Nick D. Jeffery. Vet. J. 2008 Feb; 175(2): 164-172. Quote: "The pain behaviour expressed by dogs with syringomyelia suggests that they experience neuropathic pain, probably due to disordered neural processing in the damaged dorsal horn. As such it is likely that conventional analgesic medication will be ineffective. In this review, physiological and pathological pain processing through the dorsal horn is summarised and mechanisms by which syringomyelia could result in a persistent pain state are discussed. Finally, current knowledge regarding treatment of Chiari malformation and syringomyelia is reviewed and possible drugs which may give improved pain relief in affected dogs are discussed."
A Practical Guide to Canine and Feline Neurology. Curtis W. Dewey. John Wiley & Sons; 2008; 4-6,129. Quotes: ""Breed-associated neurologic abnormalities of dogs and cats. ... Cavalier King Charles Spaniels ... Caudal occipital malformation syndrome (with syringohydromyelia) " pp. 4-6. ""Caudal occipital malformation syndrome is the canine analog of Chiari type I malformation of people. Although only recently described in dogs, COMS appears to be a very common neurologic disorder in this species. This disease is almost exclusive to small breed dogs, with the Cavalier King Charles Spaniel (CKCS) being the most overrepresented." p. 129.
Ultrasonographic Appearance of the Craniocervical Junction in Normal Brachycephalic Dogs and Dogs with Caudal Occipital (Chiari-like) Malformation. Martin J. Schmidt, Antje Wigger, Sebastian Jawinski, Tanja Golla, Martin Kramer. Vet. Radiology & Ultrasound. Aug 2008; 49(5): 472 - 476. Quote: "Ultrasonographic evaluation of the spine, especially of the spinal cord, has been rarely reported in dogs. The atlanto-occipital junction provides a small acoustic window through which examination of the craniocervical transition can be performed. Normal sonographic findings of this region in 10 normal brachycephalic dogs are presented and compared with sonographic findings from 25 Cavalier King Charles Spaniels with the caudal occipital malformation syndrome. Sonographic findings were compared with magnetic resonance imaging findings to determine the extent of cerebellar herniation and syringohydromyelia. Cerebellar displacement into the foramen magnum was clearly identified sonographically; however, syringohydromyelia was not discernable due to bone overlay."
Chiari-like malformation and syringomyelia in normal cavalier King Charles spaniels: a multiple diagnostic imaging approach. J. Couturier, D. Rault, L. Cauzinille. J Small Anim. Pract. 2008 Sept; 49(9):438-443. Quote: "Results: Of the 16 [CKCS] dogs in the study, 7 had syringomyelia (43.7%). All dogs had cerebellar herniation, suggesting Chiari-like malformation and also a tendency to occipital dysplasia. Computed tomography measurements of the caudal fossa are reported. In one dog, a syrinx was identified by ultrasonography. The only difference between dogs with or without syringomyelia was that dogs with Chiari-like malformation/syringomyelia were statistically older. Clinical Significance: The incidence of Chiari-like malformation and syringomyelia may be high in an asymptomatic population of cavalier King Charles spaniel. Computed tomography measurements reported in this study should now be compared with those of a symptomatic population to evaluate the hypothesis that dogs with Chiari-like malformation/syringomyelia syndrome have a smaller caudal fossa. This study did not identify a smaller caudal fossa in an asymptomatic cavalier King Charles spaniel population with syringomyelia. Ultrasonography probably has a low sensitivity for diagnosis of Chiari-like malformation/syringomyelia."
Intermittent "greeting" due to Chiari-like malformation/syringomyelia (CM/SM) and occipital dysplasia in a Cavalier King Charles Spaniel. Balthen-Nothen, A., Bull, C., Fehr, M., Fork, M., Tipold, A. Tieraerztliche Praxis Ausgabe Kleintiere Heimtiere 2008; 36(2):119-125. Quote: "A 5.5-year-old male Cavalier King Charles Spaniel (CKCS) was presented with an intermittent gait abnormality of one front limb. During these episodes the dog flexed one front limb for some minutes like a kind of 'greeting'. Between these episodes the dog's gait was normal. Neurological examination the neuroanatomical localization was considered to be primarily in the upper motor neuron of the cervical spine. As a diagnostic imaging tool, a magnetic resonance imaging (MRI) of the brain, cervical and thoracic spinal cord was performed and the area of the foramen magnum was shown by computed tomography. Results: In this patient a moderate herniation of the cerebellum and severe syringohydromyelia of the cervical and thoracic spinal cord (Chiari-like malformation and syringomyelia; CM/SM) was diagnosed. The foramen magnum was dorsally widened in a keyhole shape. As therapy of the syringohydromyelia a dorsal laminectomy at the level of the first cervical vertebra with fenestration of the dura mater was performed. Up to a post surgery follow-up eight weeks later, the dog no longer showed 'greeting', although in a repeated MRI the dimensions of the syrinx still remained. Conclusion: Many neurologic signs are described in association with a syrinx. This is the first case report of a CKCS presenting intermittent 'greeting'. Furthermore the dog showed a combination of two anomalies: Chiari-like malformation and syringomyelia (CM/SM) and occipital dysplasia. Clinical relevance: It is recommended that the CKCS should be screened for breeding purposes not only for occipital hypoplasia but also for occipital dysplasia. A surgical decompression of the cerebrospinal fluid-filled space can result in resolution of clinical signs, whereas MRI failed to demonstrate an improvement of the syrinx. Further studies with advanced MRI techniques would be necessary in the future to diagnose morphologic as well as functional options of the cerebrospinal fluid-filled space and -flow."
Morphology of the Caudal Fossa in Cavalier King Charles Spaniels. Sofia Cerda-Gonzalez, Natasha J. Olby, Susan McCullough, Anthony P. Pease, Richard Broadstone, Jason A. Osborne. Vet. Radiology & Ultrasound, Jan/Feb 2009;50(1):37-46. Quote: "Chiari malformations and syringohydromyelia are an important disease complex in Cavalier King Charles Spaniels. Although abnormalities in caudal fossa morphology are considered major contributors to the development of this disease, limited information exists on the range of morphologies in Cavalier King Charles Spaniels and on the relationship of these to clinically evident disease. Sixty-four Cavalier King Charles Spaniels were studied. Each underwent a neurologic examination and magnetic resonance imaging of the cervical spine and brain. T2-weighted sagittal images were used to determine both the morphologic characteristics and volume of the caudal fossa in each dog. This volume was also analyzed as a percentage of total cranial cavity volume. Each attribute was correlated with neurological grade and presence of syringohydromyelia. Fifteen dogs had neurologic signs, and 59 had morphologic abnormalities of the craniocervical junction. While 27 dogs had syringohydromyelia, 13 of these were clinically normal. Cerebellar herniation and occipital dysplasia were common findings but were not associated with syringohydromyelia. Dorsal compressive lesions were noted at the first and second cervical vertebral junction. Factors associated with the presence of neurologic signs included syringohydromyelia and the ratio of caudal fossa/total cranial cavity volume; dogs with signs had significantly larger syringohydromyelia than asymptomatic dogs. Caudal fossa size was not associated with syringohydromyelia. A positive association was identified between foramen magnum size and length of cerebellar herniation. The prevalence of craniocervical junction abnormalities is high in Cavalier King Charles Spaniels. While several factors are associated with neurologic signs, occipital hypoplasia appears to be the most important factor."
Use of magnetic resonance imaging for morphometric analysis of the caudal cranial fossa in Cavalier King Charles Spaniels. Carrera I, Dennis R, Mellor DJ, Penderis J, Sullivan M. Am J Vet Res; 2009 Mar;70(3):340-5. Quote: "Objective-To perform morphometric analysis of the caudal cranial fossa in Cavalier King Charles Spaniels (CKCSs), to assess the relationship between caudal fossa dimensions and the frequency of magnetic resonance imaging (MRI) features of occipital abnormalities in CKCSs (with and without syringomyelia), and to compare caudal cranial fossa measurements in CKCSs with measurements of 2 groups of mesaticephalic dogs. Animals-70 CKCSs and 80 mesaticephalic (control) dogs. Procedures-Dogs were placed into 4 groups as follows: Labrador Retrievers (n = 40), spaniel-type dogs (40; English Springer Spaniels and Cocker Spaniels), CKCSs with syringomyelia (55), and CKCSs without syringomyelia (15). Multiple morphometric measurements (linear, angular, and area) were obtained from cranial midsagittalT2-weighted magnetic resonance images including the brain and cervical portion of the spinal cord. Several specific MRI findings were also recorded for CKCSs that appeared to affect the occipital bone and cervicomedullary junction. Results-No significant difference was identified among breeds in control groups and between sexes in any of the groups for all morphometric measurements. Significant differences were identified in CKCSs, compared with mesaticephalic dogs, in the area of the caudal cranial fossa and for several linear measurements that reflected the length of the ventral aspect of the occipital bone. These differences were greater in CKCSs with syringomyelia. All CKCSs had abnormalities in occipital bone shape. Conclusions and Clinical Relevance-CKCSs had a shallower caudal cranial fossa and abnormalities of the occipital bone, compared with those of mesaticephalic dogs. These changes were more severe in CKCSs with syringomyelia."
Evaluation of the volumes of cranial cavities in Cavalier King Charles Spaniels with Chiari-like malformation and other brachycephalic dogs as measured via computed tomography. Schmidt MJ, Biel M, Klumpp S, Schneider M, Kramer M. Am J Vet Res. 2009 Apr;70(4):508-12. Quote: "Objective-To measure the absolute and relative volumes of cranial vaults of
Cavalier King Charles Spaniels (CKCSs) and other brachycephalic dogs for the purpose of evaluating a possible association between the volume of the caudal fossa (fossa caudalis cerebri; CF) and existence of Chiari-like malformation (CLM) and syringohydromyelia in CKCSs. Animals-40 CKCSs and 25 brachycephalic dogs. Procedures-The intracranial vault of all dogs was evaluated via computed tomography followed by magnetic resonance imaging. Volumes of the CF and the rostral and medial fossa (fossa rostralis et medialis cerebri) were determined. The ratio of the absolute volumes was calculated as the volume index (VI). Results-All CKCSs had cranial characteristics consistent with CLM. There were no significant differences between CKCSs and brachycephalic dogs with respect to the VI and absolute volumes of the CF and rostral and medial fossas. The CKCSs without syringohydromyelia (n = 26) had a median VI of 0.1842, and CKCSs with syringohydromyelia (14) had a median VI of 0.1805. The median VI of other brachycephalic dogs was 0.1864. The VI did not differ among these 3 groups. Conclusions and Clinical Relevance-Results of this study suggested that descent of the cerebellum into the foramen magnum and the presence of syringohydromyelia in CKCSs are not necessarily associated with a volume reduction in the CF of the skull."Muscular dystrophy in Cavalier King Charles spaniels. Piercy, Richard. J. and Walmsley, Gemma. Vet Rec. 2009 165 (2), p. 62. Quote: "We have recently identified the genetic cause of a form of muscular dystrophy in CKCS. The causative mutation is in the dystrophin gene and the X-linked disease is associated with weakness, muscle atrophy and exercise intolerance, detectable from a few months of age. Prominent signs in affected dogs are dysphagia [the symptom of difficulty in swallowing] and macroglossia (enlarged tongue)[tongue enlargement that leads to functional and cosmetic problems]. Serum creatine kinase is usually markedly elevated. Male dogs with the mutation [are] clinically affected and female dogs with the mutation are silent carriers. We are also keen to hear from veterinary surgeons who believe they may have seen an affected dog in their practice, in order to estimate the prevalence of this disease and limit its spread by genetic testing." Contact Dr. Piercy at the Royal Veterinary College's Comparative Neuromuscular Diseases Laboratory at rpiercy@rvc.ac.uk
Does size matter? The continuing riddle of Chiari and
syringomyelia. Simon R. Platt, Marc Kent, and Scott J. Schatzberg. J
Small Anim. Pract. 2009 Aug; 50(8):383-384.
Association between cervical and intracranial dimensions and
syringomyelia in the cavalier King Charles spaniel. H.
Carruthers, C. Rusbridge, M.-P. Dubé, M. Holmes, and N. Jeffery. J Small
Anim. Pract. 2009 Aug; 50(8):394-398. Quote: "Objectives: To investigate the
possible association between caudal fossa area and cervical vertebral
dimensions and the presence of syringomyelia in cavalier King
Charles spaniels. Methods: From magnetic resonance imaging scans of
78 cavalier King Charles spaniels, measurements were made
of the widest vertical spinal width at C1/C2, C2, C2/C3 and C3; angulation
of the C2/C3 spine; and estimated caudal fossa area. A correlation between
these measurements and syringomyelia was sought. Results: A total of 59 dogs
with and 19 without syringomyelia were compared. Older dogs had a
significantly higher incidence of syringomyelia. No difference in incidence
was noted between genders. There was no significant difference in vertebral
canal width at C1/C2 and C2, or angulation of C2/C3 between syringomyelia
and non-syringomyelia groups. The width of the canal at C2/C3 and C3 was
significantly increased in syringomyelia dogs. There was no significant
difference in the caudal fossa area between groups. Clinical Significance:
Although syringomyelia was shown to be more prevalent in older dogs, the age
beyond which dogs were considered at greater risk was not deducible from the
dataset. The association identified between wider spinal canal at C3, and
C2/C3 and syringomyelia presence is of questionable clinical significance,
as the difference between syringomyelia and non-syringomyelia groups is too
small to be measured in a clinical setting."
Chiari-like malformation in the Griffon Bruxellois. C. Rusbridge,
S. P. Knowler, L. Pieterse, and A. K. McFadyen. J Small Anim. Pract. 2009
Aug; 50(8):386-393. Quote: "It should also be realised that although
this study found a method of predicting CM in the [Griffon Bruxellois], this
may not be transferable to other breeds. This may be especially true for the
CKCS where CM is almost ubiquitous ... ."
Comparison of cerebral cranium volumes between cavalier King Charles spaniels with Chiari-like malformation, small breed dogs and Labradors. H. R. Cross, R. Cappello, and C. Rusbridge. J Small Anim. Pract. 2009 Aug; 50(8):399-405 Quote: "Objectives: To ascertain whether cavalier King Charles spaniels (CKCSs) have a proportionately smaller caudal fossa compared with other small dogs and with Labradors. ... Labradors were chosen as a 'control' group because their skull is relatively dolichocephalic and a large database of MRI scans was available. ... To evaluate if cerebellar herniation in CKCS correlates with caudal fossa volume. Methods: In this retrospective study, three-dimensional images were created from magnetic resonance imaging brain series of 117 dogs (split into three groups: CKCS, Labradors and small breeds) from which the volumes of the fossae and brain parenchyma were calculated. These volumes were transformed into percentages of total cranial cavity and parenchyma volumes, respectively. The percentages were statistically compared among the groups. The percentage of herniated cerebellum in the CKCS was compared using linear regression with the caudal fossa and parenchyma percentages. Results: ... When compared with Labradors, CKCS had proportionately the same volume of parenchyma in their caudal fossa, hence there is a mismatch of volumes with too much parenchyma in a too small caudal fossa causing overcrowding. This supports either theory of pathogenesis of CM as mesoderm insufficiency during embryology − causing insufficient scope for the mesoderm and ectoderm layers to develop ... − or alternatively premature growth plate closure. Other small breeds of dogs had a proportionately smaller volume of parenchyma in their caudal fossa which can explain why, despite having a similar sized caudal fossa to CKCS, they do not experience overcrowding. It is hypothesised that through the miniaturisation process of other small dogs, both the cranium and brain are proportionately smaller but in CKCS only the cranium has reduced in volume, hence why there is a higher incidence of CM in CKCS than other small breeds. Cavalier King Charles spaniels also had a greater percentage of their cranial fossa filled with parenchyma (cranial fossa parenchyma percentage) compared with small breeds and Labradors which had a similar percentage. Overcrowding in CKCS might therefore occur due to a mismatch in volumes in both the caudal fossa and cranial fossa of the skull, suggesting the cranial fossa is also involved in the pathophysiology of CM. From this study, all CKCS are at an increased risk of showing cerebellar distortion visible on MRI scans due to caudal fossa overcrowding, but the volume measurements are unable to predict cerebellar herniation which may be influenced by other skull abnormalities like occipital dysplasia resulting in a wider FM ... . Furthermore, RI scans of young CKCS may not help to predict the development of SM in later life as a complication to CM. Therefore, it is necessary for further studies to be conducted in order to investigate correlations between cranium volumes and disease progression and clinical signs."
Characteristics of Cerebrospinal Fluid Flow in Cavalier King Charles Spaniels Analyzed Using Phase Velocity Cine Magnetic Resonance Imaging. Sofia Cerda-Gonzalez, Natasha J. Olby, Richard Broadstone, Susan Mccullough, Jason A. Osborne. Vet. Rad. & Ultrasound, Sep/Oct 2009, 50(5):467-476. Quote: "Syringomyelia is an important morbidity source in Cavalier King Charles Spaniels. Although abnormal cerebrospinal fluid (CSF) flow secondary to Chiari malformations is thought to cause syringomyelia in humans, this relationship is unknown in dogs. We used phase-contrast magnetic resonance (MR) imaging to evaluate CSF flow in dogs. Fifty-nine Cavalier King Charles Spaniels were assigned a neurologic grade reflecting their neurologic status. Five normal control dogs of other breeding were imaged for comparison. The presence of syringomyelia was noted from sagittal MR images. The pattern and velocity of CSF flow were assessed using phase-contrast cine MRI at the foramen magnum, C2–C3 disc space, and within syrinxes. Flow was measured most easily with the neck flexed to mimic standing. CSF flow velocity in the dorsal aspect of the subarachnoid space at the foramen magnum was significantly higher in control dogs than Cavalier King Charles Spaniels (P=0.035). Flow was obstructed at the foramen magnum in 41 of 59 Cavalier King Charles Spaniels. Turbulent flow and jets were associated with syringomyelia presence and severity, and CSF flow velocity at C2/3 dorsally was inversely related to the presence of syringomyelia (P=0.0197). Peak dorsal subarachnoid space CSF flow velocity at the foramen magnum and C2–C3 were together highly predictive of syringomyelia. CSF flow can be assessed in dogs using phase-contrast cine MRI. Obstruction to flow at the foramen magnum is common in Cavalier King Charles Spaniels and CSF flow pattern and velocity are related to the presence of syringomyelia."
Volumetric Analysis Of Brain Parenchyma Within The Caudal Fossae Of Cavalier King Charles Spaniels. C Driver, C Rusbridge, H Cross, HA Volk. 22nd ECVN Annual Symposium, Sept. 2009; J Vet Intern Med, Jan/Feb 2010;24(1):242. Quote: "Chiari-like malformation (CM) and syringomyelia (SM) is a debilitating disease complex recognized in the Cavalier King Charles Spaniel (CKCS). Mesoderm insufficiency during embryogenesis has been suggested as the pathogenesis of Chiari type-I malformations in humans leading to a small posterior fossa but a normally developed hindbrain. No volumetric evidence exists regarding the role of hindbrain volume within the caudal fossa in the development of SM in dogs. Magnetic resonance (MR) images of 59 CKCS with CM and no other systemic disease were retrospectively reviewed. ... Volumes of hindbrain parenchyma were analyzed as percentages of caudal fossa volume and caudal fossa volume was analyzed as a percentage of total cranial cavity volume. The volume of the ventricular system was recorded as a percentage of total parenchymal volume. If SM was present, syrinx size was measured from T2 weighted MR images from the maximal dorsoventral dimension within the cervical spine. SM was present in 40/59 (68%) dogs. All data was normally distributed. There was no significant (t-test, p
=5 0·702) age difference between dogs with (61.2 ± 33.8 months; 6.8–128.9) or without SM (57.4 ± 37.1 months; 3.9–122.8). Caudal fossa percentage of the total cranial cavity volume did not differ significantly (t-test, p=5 0·520) between dogs without (14.4 ± 1.5%) or with (14.9 ± 1.3%) SM. However, there was a significant difference (p=50·002) between the two groups looking at hindbrain parenchyma percentage of the caudal fossa (86.7 ± 4.1% and 89.9 ± 1.67% respectively). Furthermore, in the SM group a significant positive association was found between the hindbrain parenchyma percentage and syrinx size (spearman r=5 0·437). No significant difference (p=5 0·164) was found between the two groups for ventricular volume (5.30 ± 7.68% and 7.73 ± 5.36% respectively), however when a syrinx was present a strong positive correlation was found between ventricular and syrinx size (spearman r=5 0·500). This work supports recent evidence that caudal fossa size is not associated with SM, but that overcrowding of the caudal fossa leads to SM and may be caused by mesoderm insufficiency. The association between ventricle and syrinx dimensions supports the theory that SM develops as a result of altered CSF dynamics."Anatomical Distribution of Syringomyelia in Cavalier King Charles Spaniel With Chiari.Like Malformation. S Loderstedt, L Benigni, K Chandler, C Lamb, C Rusbridge, HA Volk. 22nd ESVN Annual Symposium, Sept. 2009; J Vet Intern Med, Jan/Feb 2010;24(1):253. Quote: "The objective of this study was to evaluate the prevalence and anatomical distribution of syringomyelia (SM) in clinically-affected CKCS. It was hypothesised that (1) SM is not restricted to the cervical region of the spine, (2) the maximal syrinx diameter can occur anywhere along the spinal cord, (3) there is an association between cervical syrinx diameter and distribution and SM in other regions of the spinal cord. Thirty-seven CKCS with clinical evidence of SM were studied prospectively. Magnetic resonance (MR) imaging of the brain and the entire spinal cord of each dog were performed at 1.5 Tesla. ... SM was not limited to the cervical region. SM was present in the region of the C1-C4 vertebral bodies in all dogs (100%) however it often was not limited to that area being also found at C5- T1 in 31/37 (84%), T2-L2 in 29/37(78%) and L3-L6 in 21/37 (57%). Maximal SM diameter occurred at C1-C4 in 19/37 (51%) dogs, at C5- T1 in 2/37 (5%), at T2-L2 in 15/37 (41%) and at L3-L6 in 1/37(3%) dogs, respectively. There was no significant difference between the mean syrinx diameter at the region C1-C4, C5- T1 and T2-L2 but mean syrinx diameter was less in the region L3-L6. Mean syrinx diameter at C1-C4 was positively correlated with mean syrinx diameter at C5- T1, T2-L2 and L3-L6 respectively. Many CKCS with a cranial cervical syrinx also have a syrinx affecting more caudal regions of the spinal cord. Dogs with a large cranial cervical syrinx tend to also have a large syrinx more caudal. MR imaging restricted to the cervical region will underestimate the extent of the syrinx and the severity of the disease process in the majority of dogs."
Foramen Magnum Decompression with Free Autogenous Adipose Tissue Graft for Treatment of Caudal Occipital Malformation Syndrome in Dogs. Erin Y. Akin, Nora H. Ortinau, Andy Shores, M. B. Carnes, Jill Narak. 2009 ACVS Vet. Symposium Abstract. Quote: "The objective of this study was to describe and evaluate a modified surgical technique using foramen magnum decompression (FMD), durotomy, duroplasty with swine intestinal submucosa (SIS), and a free autogenous adipose tissue graft (FAATG) for the treatment of canine caudal occipital malformation syndrome (COMS). Fourteen client-owned dogs with MRI evidence of COMS and surgical treatment with FMD were included in this 18-month prospective study (10/07 – 3/09). Breeds treated included Cavalier King Charles Spaniel (11), Chihuahua (2), and Pomeranian (1). Surgical decompression of the foramen magnum and durotomy were performed in a fashion similar to previously described techniques. ... The dura was marsupialized, suturing it to the surrounding fascia using simple interrupted sutures of 5-0 polydioxanone (fig 3). The SIS was sutured to the dura in a tent-like fashion using simple interrupted sutures of 5-0 polydioxanone. The FAATG, typically obtained from the gluteal region, was placed over the defect followed by a sheet of gelatin foam. ... Overall, recovery was considered to be good to excellent by owners. To date, none of the patients that have undergone this surgical procedure have required further surgical intervention due to postoperative compressive scar formation that has been reported in the previous literature. ... In dogs that require FMD in the treatment of COMS, this modified technique using a FAATG should be considered. Current clinical outcomes of patients that were treated for COMS using this technique showed excellent results similar to current published literature without intraoperative complications and clinical improvement with a decrease in clinical signs postoperatively. The use of the titanium mesh, placement of the screws, and the exothermic reaction of the overlying methyl methacrylate may contribute to tissue trauma. The authors conclude that with the results of this study, this procedure is clinically effective and the use of a titanium mesh, additional hardware and methyl methacrylate offers no advantage in canine COMS patients."
Heritability of syringomyelia in Cavalier King Charles spaniels. Tom Lewis, Clare Rusbridge, Penny Knowler, Sarah Blott, John A. Woolliams. Vet.J. 183(3): 345-347 Mar. 2010. Quote: "Mixed model analysis of 384 Cavalier King Charles spaniels (CKCS), with a magnetic resonance imaging diagnosis for the presence or absence of a syrinx, in conjunction with the Kennel Club pedigree records of all dogs registered from the mid 1980s to September 2007, revealed a moderately high estimate of heritability of syringomyelia (h2 = 0.37 ± 0.15 standard error) when analysed as a binary trait. Inspection of cases where the disease segregated within families pointed to genes at more than one locus influencing syringomyelia. The availability of estimated breeding values for Kennel Club registered CKCS is a significant step in being able to select against syringomyelia, particularly given the difficulty of ascertaining the disease phenotype."
Syringomyelia in the Cavalier King Charles spaniel (CKCS) dog. Katheryn C. Wolfe, Roberto Poma. Can Vet J;51:95-102; Jan 2010. Quote: "Recent data suggest that CM in the Cavalier King Charles spaniel (CKCS) is inherited. The incidence of CM in the CKCS breed is an estimated 95% and current studies suggest that SM is present in more than 50% of dogs with CM with approximately 35% of affected dogs exhibiting clinical signs. ... Overall, the prognosis for CM/SM-affected dogs depends on the severity of clinical signs and on the response to medication. Chiari-like malformation and syringomyelia is a progressive condition in those dogs that are affected clinically. Some dogs will need constant dose adjustments to adequately treat their symptoms. Unfortunately, some dogs afflicted with severe and disabling pain do not respond to medical management and are not surgical candidates, in which cases a thorough evaluation of their quality of life is necessary."
Optimisation of breeding strategies to reduce the prevalence of inherited disease in pedigree dogs. Lewis, T.W.; Woolliams, J.A.; Blott, S.C. Animal Welfare 19(Supp 1):93-98(6), May 2010. Quote: "One option for improving the welfare of purebred dog breeds is to implement health breeding programmes, which allow selection to be directed against known diseases while controlling the rate of inbreeding to a minimal level in order to maintain the long-term health of the breed. The aim of this study is to evaluate the predicted impact of selection against disease in two breeds: the Cavalier King Charles spaniel (CKCS) .... Heritabilities for mitral valve disease, syringomyelia in the CKCS ... were estimated to be 0.64 (± 0.07), 0.32 (± 0.125) ... respectively, which suggest encouraging selection responses are feasible based upon the estimation of breeding values (EBVs) if monitoring schemes are maintained for these breeds. Although using data from disease databases can introduce problems due to bias, as a result of individuals and families with disease usually being over-represented, the data presented is a step forward in providing information on risk. EBVs will allow breeders to distinguish between potential parents of high and low risk, after removing the influence of life history events. Analysis of current population structure, including numbers of dogs used for breeding, average kinship and average inbreeding provides a basis from which to compare breeding strategies. Predictions can then be made about the number of generations it will take to eradicate disease, the number of affected individuals that will be born during the course of selective breeding and the benefits that can be obtained by using optimisation to constrain inbreeding to a pre-defined sustainable rate."
Genome wide linkage studies identifies a novel locus for syringomyelia associated with Chari-like malformation in the Cavalier King Charles Spaniels. Quoc-Huy Trink, Penny Knowler, Alexandra Thibault, Marie-Pierre Dubé, Guy A. Rouleau, Clare Rusbridge, and Zoha Kibar. May 20, 2010. On-line pdf here.
Relationship of brain parenchyma within the caudal cranial fossa and ventricle size to syringomyelia in cavalier King Charles spaniels. C. J. Driver, C. Rusbridge, H. R. Cross, I. McGonnell, and H. A. Volk. J Small Anim. Pract.; July 2010; 51(7):382-386 Quote: "Objectives: To assess if the volumes of the caudal cranial fossa (CCF), parenchyma within the caudal cranial fossa (CCFP) or ventricles (V) are associated with syringomyelia (SM) in cavalier King Charles spaniels (CKCS) with Chiari-like malformation (CM). To evaluate if volumes are associated with transverse syrinx width. Methods: Magnetic resonance images of 59 CKCS with CM were retrospectively reviewed and grouped with or without SM. Three-dimensional images were created and volumes of the fossae, brain parenchyma and ventricular system were calculated from which percentages of CCF, CCFP and V were created. If present, syrinx size was measured from its maximal transverse width. The percentages were statistically compared between groups, and correlation between percentages and syrinx dimensions was made. Results: CKCS with SM had significantly higher CCFP (P=0·0001) and V (P=0·0002) to those without but no significant difference in CCF (P=0·925). There was a positive correlation between CCFP and syrinx width (Pearson r=0·437) and ventricle size to syrinx width (Spearman r=0·627). Clinical Significance: A more marked overcrowding of the CCF is associated with SM, which may explain the high incidence of SM in CKCS with CM. The association between ventricle and syrinx dimensions supports the theory that SM development is the result of altered cerebrospinal fluid dynamics." See also: Volumetric Analysis Of Brain Parenchyma Within The Caudal Fossae Of Cavalier King Charles Spaniels, above.
Canine Chiari-like Malformation: A Comparison of Ventricular and Caudal Fossa Volumes in Cavalier King Charles Spaniels > 5 years of age that have not developed Syringomyelia vs those Affected when < 2 years. C Driver, C Rusbridge, HA Volk. Abstract at 2010 BSAVA conference. MRIs of 21 Cavalier King Charles spaniels under 2 years affected with CM/SM, and 14 CKCSs over 5 years with only CM were analyzed. Conclusion: Severe SM in Cavaliers under 2 years old is associated with greater mis-match between hindbrain and caudal fossa volume than found in older CKCSs with CM but no SM. They also measured the dimensions of the brain's ventricle cavities of SM-affected Cavaliers, and they found that the ventricle volumes had a direct correlation with the width of the syrinx.
Transcranial Magnetic Motor Evoked Potentials, Somatosensory Evoked Potentials, Spinal Evoked Potentials and Brainstem Auditory Evoked Potentials in Cavalier King Charles Spaniel Dogs with and Without Syringomyelia. K Wolfe, S Nykamp, DG Allen, J Armstrong, R Poma. J Vet Intern Med 2010;24:--- (ACVIM 28th Ann. Vet. Med. Forum Abstract Program: Abstract 231). Quote: "The aim of this study was to evaluate the validity of transcranial magnetic motor evoked potentials (TMMEP), somatosensory evoked potentials (SSEP), spinal evoked potentials (SEP) and brainstem auditory evoked responses (BAER) in the assessment of motor and sensory pathways throughout the central nervous system of CKCS dogs with and without SM diagnosed by MRI. Fifty CKCS dogs were evaluated. Neurologic deficits were graded 0–3 (0 5 normal, 1 5 cervical or thoracolumbar pain on palpation, 2 5 cervical or thoracolumbar pain on palpation plus evidence of neuropathic pain, 3 5 ataxia or paresis). TMMEP, SSEP, SEP, and BAER were performed on all dogs under sedation with hydromorphone (0.05 mg/kg IV) and acepromazine (0.025 mg/kg IV). Onset latencies (msec) were measured for TMMEP, SSEP and SEP and IV interpeak latencies were measured for BAER. Dogs were anesthetized for brain and spinal cord MRI (cervical, thoracolumbar, lumbar) including sagittal and transverse T2-weighted images. ... Based on neurologic score and MRI findings, all dogs were classified into group A (n 5 16) (neurologic abnormalities and MRI confirmed SM), B (n 5 9) (neurologic abnormalities and no SM), C (n 5 11) (normal neurologic examination and MRI-confirmed SM), and D (n 5 14) (normal neurologic examination and no SM). There were no significant differences observed in the mean latencies of TMMEP, SSEP, SEP and BAER between groups A, B, C and D. However, a significant linear correlation was observed between the severity of neurologic dysfunction and size of the syrinx (p 5 0.017; t-test procedure, SAS) with a larger syrinx being associated with more severe neurologic signs. In conclusion, TMMEP, SSEP, SEP and BAER do not appear to be valuable tests in detecting functional abnormalities of the motor and sensory pathways throughout the central nervous system of CKCS dogs with and without neurological signs secondary to SM diagnosed by MRI."
Association between Chiari-like malformation and syringomyelia in cavalier King Charles spaniels. C. J. Driver, C. Rusbridge, H. R. Cross, I. McGonnell, and H. A. Volk. Vet Rec., Aug. 2010 167:306.
Breed Predispositions to Disease in Dogs & Cats (2d Ed.). Alex Gough, Alison Thomas. 2010; Wiley-Blackwell Publ. 52.
Concurrent occipital hypoplasia, occipital dysplasia, syringohydromyelia, and hydrocephalus in a Yorkshire terrier. Laura Cagle. Can Vet J. 2010 Aug.; 51(8): 904–908.
The Incidence of Syringomyelia in the Cavalier King Charles Spaniel. J. E. Parker, S. P. Knowler, C. Rusbridge, T. J. McKinley, E. Noorman and N. D. Jeffery. Abstract at 23d ECVN symposium, Sept. 2010. Quote: "The epidemiology of cervical syringomyelia in a population of 804 Cavalier King Charles Spaniels (CKCS) was investigated using the results of a voluntary MRI screening programme that is ongoing in the United Kingdom (UK) and the Netherlands. The aim of the study was to establish the incidence of disease and to determine the risk factors for its development. ... The lifetime risk of developing syringomyelia in the study population was estimated to be 55%. Of the variables investigated, only the age at which a scan was performed significantly predicted the outcome of screening and the likelihood of detecting the disease increased with age-at-scan up to the age of four years. The predictive accuracy of the final model was 62.4% and factors not evaluated by this study are therefore also likely to contribute to the timing of disease manifestation. It is concluded that syringomyelia is likely to be one of the most common disease conditions of the CKCS. The age at which an MRI scan is performed predicts the likelihood of disease detection and a susceptible individual may not express the diagnostic phenotype until the age of four. Performing screening before this time may give a false negative result for the lifetime risk of disease development."
Interim Breeding Guidelines -- 4 Year Report. SP Knowler, AK McFadyen, C Rusbridge. Abstract at 23d ECVN symposium, Sept. 2010. Quote: "...a cohort of 465 dogs (307 females, 158 males) were identified which had either one (316 dogs) or both parents (149 dogs) with MRI confirmed CMSM status. Of these, 393 were CKCS [cavalier King Charles spaniels] and 72 were Griffon Bruxellois. All dogs were assigned an A - F CMSC grade according to the current breeding guidelines. Grade A implies a SM unaffected dog over 2.5 years old. In addition, to estimate the influence of late onset SM, an Grade A* was assigned to Grade A dogs over 5 years old. The CMSM grade of all offspring from all possible breeding combinations including using one parent of unknown status (Grade U) was ascertained. Offsrping without SM only occurred when there was at least one parent of Grade A status. There were higher numbers of SM clear offspring if both parents had A status. In addition all A* offspring also had at least one A* parent and higher numbers of A* offspring resulted from crosses where both parents were A*. There was no influence of gender on SM affectedness. All offspring were SM affected if both parents were SM affected. SM affected offspring may also occur when SM unaffected dogs are used (15.4% from A x A parent crosses and 7.7% from A* x A* parental crosses). Using dogs of unknown status was risky for SM affectedness. Fifty percent of older offspring were SM affected in A x U parental crosses and there were higher numbers of SM affected dogs with other parental combinations that included one Grade U dog. In conclusion, to increase the number of SM unaffected offspring, at least one parent should be ascertained to be free of SM by MRI at 2.5 years of age. Ideally both parents would be free of SM at 2.5 years of age and the true SM status of the grandparents at least 5 years old should be established. It is recommended that all breeding dogs from breeds susceptible to CMSM be MRI screened and results submitted to an officially recognised central database."
Morphometric Assessment Of Cranial Volumes In Age-Controlled Cavalier King Charles Spaniels With And Without Syringomyelia. C. J. Driver, C. Rusbridge, I. M. McGonnell, H. A. Volk. Vet.Rec.; Dec 2010; 167:978-979. Quote: "Cavalier King Charles spaniels (CKCS) with Chiari-like malformation (CM) and syringomyelia have more brain parenchyma within the caudal cranial fossa (CCF) (CCFP), and also display ventriculomegaly, compared with CKCS with CM alone (Driver and others 2010). ... This short communication describes a retrospective, volumetric comparison of three variables (CCF, CCFP and ventricular dimensions) between CKCS with syringomyelia when less than two years of age and CKCS older than five years without syringomyelia. ... Dogs were grouped into those diagnosed with CM and syringomyelia when less than two years of age, and those with only CM aged five years or older when scanned. ... There was a significant difference in ventricular dimensions between the young dogs with syringomyelia ... and the unaffected older dogs ... Similarly, mean (sd) CCFP was significantly different between the groups.... Furthermore, the young CKCS with syringomyelia had a smaller mean ... than the unaffected older dogs ... These results are consistent with previous findings that ventriculomegaly and a small but significant increase in caudal fossa parenchyma are associated with syringomyelia (Driver and others 2010). The present results suggest that the CCF volume is also significantly smaller in dogs with syringomyelia. ... The development of syringomyelia may be related to a cumulative effect of a small CCF and enlarged CCFP; however, as there is little difference between the measurements numerically, it is unknown how this would affect CKCS clinically and biologically. Further cohort and longitudinal studies are required to assess whether measuring the ventricular dimensions would be useful in differentiating CKCS that will develop syringomyelia from those that will not."
Distribution of syringomyelia along the entire spinal cord in clinically affected Cavalier King Charles Spaniels. Shenja Loderstedt, Livia Benigni, Kate Chandler, Jacqueline M. Cardwell, Clare Rusbridge, Christopher R. Lamb, and Holger A. Volk. Vet.J. 2011 187:---. Quote: "Chiari-like malformation (CM) and syringomyelia (SM) is an important disease complex in the Cavalier King Charles Spaniel (CKCS) but data about the anatomical distribution of SM along the spinal cord are lacking in veterinary medicine. The objective of this study was to define the anatomic distribution of SM in CKCS clinically affected by CM/SM. Magnetic resonance imaging (MRI) of the brain and the entire spinal cord of 49 dogs was performed and different morphological parameters compared. ... CM was present in all patients. ... All dogs in the present study were clinically affected. ... SM was absent in 25% of dogs with clinical signs. ... {I}maging only the cervical spine in clinically affected CKCSs is likely to underestimate the total syrinx size and the anatomical distribution of SM. The presence of cervical SM in all dogs with MRI evidence of SM could however justify the restricted imaging under screening purposes. ... In the majority of cases in our study, the syrinx borders were not well demarcated on T2-weighted MR images. Syrinx outlines were however distinctly visible in T1-weighted images. ... The results of our study showed syrinx formation in all regions of the spinal cord with no significant differences of [syrinx size] between the cervical, cervicothoracic and thoracolumbar regions, but significantly smaller syrinx in the caudolumbar spinal region. ... In our study Smax was most often seen within the C1–C4 region and, interestingly, also over T2–L2 vertebral bodies. ... Our data offer a description of the distribution and size of SM in clinically affected CKCS and challenge the current pathophysiological theories. ... We found that the severity of SM was positively correlated with patient age. This is consistent with previous studies indicating that CKCS with SM were significantly older than dogs without SM (Couturier et al., 2008). It seems likely therefore, that SM is a progressive disease in dogs. ... There is a very high potential for CKCS with clinical signs of CM/SM to develop SM in more than one spinal cord region. Diagnostic imaging limited to the cervical spine in clinically affected CKCS is likely to underestimate the degree and severity of SM. It can be hypothesised that SM has a progressive nature in CKCS, which requires further characterisation."
Growth of Clinical Veterinary Magnetic Resonance Imaging. Patrick R. Gavin. Vet.Rad. & Ultra.; Mar/Apr 2011; 52(s1):52-54. "In the spine, MR imaging reveals conditions which were previously difficult to diagnose ante-mortem, and may facilitate study of their pathophysiology. Examples include syringohydromyelia associated with Chiari-like malformation in the Cavalier King Charles spaniel... ."
Correlating Magnetic Resonance Findings with Neuropathology and Clinical Signs in Dogs and Cats. Charles H. Vite, Johnny R. Cross. Vet.Rad. & Ultra. Mar/Apr 2011; 52(1),Supp. 1:S23–S31.
Evaluation of cerebrospinal fluid in Cavalier King Charles Spaniel dogs diagnosed with Chiari-like malformation with or without concurrent syringomyelia. Whittaker DE, English K, McGonnell IM, Volk HA. J Vet Diagn Invest. 2011 Mar;23(2):302-7. "Syringomyelia is a common clinical problem in the Cavalier King Charles Spaniel dog population. The underlying pathophysiology of the development and progression of syringes is currently unknown. The primary aim of the current study was to determine whether development of syringomyelia is accompanied by alterations in cerebrospinal fluid composition. Patient records of Cavalier King Charles Spaniels with Chiari-like malformations, with or without concurrent syringomyelia, that had magnetic resonance imaging and cerebrospinal fluid analysis between December 2004 and December 2009, were retrospectively reviewed. Total nucleated cell count per microliter, with differential count, red blood cell count per microliter, and protein concentration (g/l), were reviewed. Data were analyzed with the Mann-Whitney U-test. Spearman rank test was used to test association between cerebrospinal fluid composition and syrinx size, and the Fisher exact test was used to compare the presence of macrophages, reactive lymphocytes, and myelin. A P value of ≤0.05 was considered significant for statistical tests. Dogs with syringomyelia had a higher total nucleated cell count (syringomyelia: 4/µl [range, 0-15/µl] vs. without syringomyelia: 2/µl [0-8/µl]; P = 0.0047), higher protein concentration (syringomyelia: 0.26 g/l [0.07-0.42 g/l] vs. without syringomyelia: 0.2 g/l [0.12-0.39 g/l]; P = 0.039), and an increased neutrophil percentage (syringomyelia: 0% [0-37%] vs. without syringomyelia: 0% [0-21%]; P = 0.0203) than those with the Chiari-like malformation alone. There was a positive correlation between total nucleated cell count and syrinx size (r = 0.51; P = 0.0068). Development of syringomyelia is accompanied by alterations in cerebrospinal fluid composition. The pathogenesis of syringomyelia has not been fully elucidated; therefore, the exact origin of cerebrospinal fluid changes remains unclear."
Effects of syringomyelia on electrodiagnostic test results in Cavalier King Charles Spaniels. Thomas R. Harcourt-Brown, Zoe Belshaw, John E. Parker, Nick D. Jeffery, Nicolas Granger. Am J Vet Res, May 2011;72(5):595-600. Quote: "Objective — To determine the effects of syringomyelia on electromyography (EMG) findings, somatosensory-evoked potentials (SEPs), and transcranial magnetic motor-evoked potentials (TMMEPs) in Cavalier King Charles Spaniels (CKCSs). Animals — 27 client-owned CKCSs that underwent prebreeding magnetic resonance imaging screening or investigation of clinical signs consistent with syringomyelia. Procedures — In dogs with (n = 11) and without (16) magnetic resonance imaging-confirmed syringomyelia, the median nerve in each thoracic limb was stimulated and SEPs were recorded over the C1 vertebra; onset latency and latency and amplitude of the largest negative (N1) and positive (P1) peaks were measured. The TMMEPs were recorded bilaterally from the extensor carpi radialis and tibialis cranialis muscles; onset latencies in all 4 limbs were measured. Bilateral systematic needle EMG examination was performed on the cervical epaxial musculature, and the number of sites with spontaneous activity was recorded. Results — In dogs with syringomyelia, amplitudes of N1 and P1 and the amplitude difference between P1 and N1 were significantly smaller than those recorded for dogs without syringomyelia (approx 2-fold difference). No difference in SEP latencies, TMMEP latencies, or the proportion of dogs with > 2 sites of spontaneous activity detected during EMG examination was detected between groups. Conclusions and Clinical Relevance — Results indicated that SEP amplitude at the C1 vertebra was a more sensitive measure of spinal cord function in CKCSs with syringomyelia, compared with results of EMG or TMMEP assessment. Measurement of SEP amplitude may have use as an objective assessment of the evolution and treatment of this disease."
Whole Genome Study Identifies a Candidate Region for Chiari-like Malformation in Brussels Griffon. LeMay P, Trinh QH, Dubé MP, Rusbridge C, Rouleau GA, and Kibar Z. Sainte-Justine University Hospital Center Research Center 18 June 2011. Quote: “Chiari malformation type 1 (MCI) ... in humans is similar to a disease in dogs called Chiari-like malformation (CM). This disease has a particularly high incidence in the Brussels Griffon breed (GB). ... Results: Analysis of type case / control genotypes generated by the study of whole-genome association identified six genomic regions with significant scores. ...[A] genomic region on chromosome 2 was significantly associated with MC (P = 1.9x10-5 when corrected EIGENSOFT). Haploview identified a haplotype block extending over a region of 2.9 Mb which is significantly associated with CM with a P value of 6.87 x10-10. The fine mapping has identified three new SNPs significantly associated with CM with P values of 1.938x 10-6, 1.61x 10-5, 5.36x 10-6 in addition to allowing a reduction in haplotype 1.7 Mb. Conclusion: A region of a 1.7 Mb on chromosome 2 is associated with CM in the GB. To reduce this region, other breeds genetically related to GB and affected by CM will be genotyped to identify a region shared by CM affected. In addition, a case / control over a larger cohort will increase the resolution of this region."
Prevalence of asymptomatic syringomyelia in Cavalier King Charles spaniels. J. E. Parker, S. P. Knowler, C. Rusbridge, E. Noorman, N. D. Jeffery. Vet.J. June 2011. Quote: "The prevalence of syringomyelia was investigated in a sample population of 555 Cavalier King Charles spaniels. All dogs, which were declared by their owners to be showing no clinical signs of syringomyelia, underwent MRI to determine the presence or absence of the condition. Data were analysed by logistic regression to determine the effects of sex and age on the prevalence of syringomyelia. Only increased age was found to have a significant effect. The prevalence of syringomyelia was 25 per cent in dogs aged 12 months, increasing to a peak of 70 per cent in dogs aged 72 months or more. ... The evidence for a lower prevalence in younger animals is more reliable (because of the higher numbers included in the present study and the lower likelihood of false inclusion) and this effect lasts until dogs are at least three years of age. This finding has important implications for the design of a screening test procedure and may conflict with the current recommendations that the optimum age for screening should be 30 months. These data would imply that it is probable that dogs aged up to three years may yet have reduced odds for the diagnosis of syringomyelia. However, there is a need for the dogs to be screened when they are reasonably young so that breeders can decide at an early stage whether their animals are suitable for breeding; many breeders would consider 36 months unduly old.... The high lifetime prevalence of syringomyelia raises concerns for the welfare of the CKCS breed and also suggests that eliminating the genetic risk factors for the disease by selective breeding may be difficult, because the heritability has previously been shown to be complex, and the prevalence of the determinant genes within the population is therefore likely to be high. The true prevalence of syringomyelia in the general CKCS population is expected to be higher than that found in this sample population because symptomatic dogs were specifically excluded."
Preliminary Morphometric Evaluation of Syringomyelia in American Brussels Griffon Dogs. A.C. Freeman, S.R. Platt, M. Kent, E. Huguet. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract N-3). Quote: "The aims of this study were to investigate the ABG for (i) the prevalence of skull abnormalities; (ii) the prevalence of SM; (iii) an association between lateral ventricular size, cerebellar size and SM; and (iv) associations between SM, skull abnormalities, CSF pleocytosis and clinical signs. Seventy-six ABGs, recruited as part of a larger epidemiological and genetic study, underwent brain and spinal MRI evaluation ... . All dogs were evaluated neurologically, recording deficits and the presence of spinal pain. ... . Forty-five dogs underwent atlanto-occipital cerebrospinal fluid tap at the time of MRI and the white blood cell (WBC) count was recorded. ... The mean age of the 30 males (24 intact) and the 46 females (34 intact) was 50.4 months (range 8–135; median 44 months). Neurological deficits and neck pain were noted in 21 (27%) and 15 (19.7%) of dogs respectively; 5 dogs (6.57%) exhibited both. Cerebellar deviation and vermal herniation were present in 37 (48.68%) and 46 (60.52%) dogs respectively; twenty-three dogs (30.26%) had both. Mean height of the CC was 2.3mm (0–7.2 mm). Forty (52.63%) Ccs were greater than 2mm in height; the mean length of these lesions was 2.03 vertebrae (0.5–7). Mean CSF WBC count was 4.97/µl (0– 39). Syrinx height and extent were significantly higher in dogs with neurological signs (size p = 0.01; extent p 5= 0.0004). There were no significant differences in syrinx sizes and extent in dogs with or without skull abnormalities or spinal pain. There were no associations of syrinx height or extent with CSF WBC count or age of dog. Intact females had a significantly lower syrinx extent than intact males (p = 0.009). There were no significant differences in presence of spinal pain or neurological signs between dogs with or without skull abnormalities. There was a significant negative association of ventricular percentage and cerebellar percentage (p < 0.0001). There was a significant association of ventricular percentage with syrinx percentage (p = 0.0015) and height (p = 0.0007). This study suggests that SM and CM are prevalent in ABGs. Syrinx size and extent are associated with neurological signs and ventriculomegaly is associated with both small cerebellar size and large syrinx size. However, SM may not be associated with CM as defined by cerebellar herniation and deviation and is not associated with CSF inflammation."
Chiari-like Malformation, Syringomyelia and Neuropathic Pain: Cerebrospinal Fluid Neurotransmitter and Cytokine Levels. S.R. Platt, A.C. Freeman, M. Kent, E. Huguet, G. Edwards, R. Barber. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract 93B). Quote: "The pathogenesis of neuropathic pain (NP) and syringomyelia (SM) in association with Chiari-like malformation (CLM) in dogs has focused on the anatomical anomalies and secondary cerebrospinal fluid (CSF) flow abnormalities. Neuropathic pain in humans has been associated with abnormalities of neurotransmitters such as glutamate and serotonin as well as immunologic mechanisms. The aim of this study was to investigate the CSF neurotransmitter and cytokine levels in Brussels Griffon dogs (BGs) with CLM, SM and NP. As part of an MRI study investigating the prevalence of SM in BGs, atlanto-occipital CSF was acquired from 46 dogs and stored at -80C until analysis. ... Deproteinized CSF samples were analysed for presence of serotonin (ng/ml), glutamate, glycine and GABA (mg/ml) by high performance liquid chromatography. ... All hypothesis tests were 2-sided and the significance level was á = 0.05. NP was detected in 8 dogs (17%); SM was present 24 dogs (52%); and CM was detected in 24 dogs (52%). IFN-g levels were significantly lower in dogs with NP than without (p = 0.036). There were significant positive correlations between syrinx size and IL-8 (p = 0.017),KC(p = 0.025) and MCP-1 (p = 0.003). There were significant negative correlations between IFN-g and syrinx height (p = 0.025) and extent (p = 0.042). There was a significant negative correlation between IL-2 and syrinx height (p = 0.042). Neurotransmitter levels were not associated with skull abnormalities or spinal pain, but there was a positive correlation of glycine with IL-2 (p = 0.004) and MCP-1 with glutamate (p = 0.0147) and serotonin (p = 0.0059). The size of the syrinx in BGs with SM is associated with several cytokine elevations but only a decrease of IFN-g was associated with NP. Based on this study it does not appear that excitotoxicity plays a role in either SM development or NP. Further work is justified on the role of the immune system in CM, SM and NP."
Effect of Omeprazole on Serum Gastrin Concentrations and Calcium Metabolism in Healthy Dogs. O. Dossin, K. Jones, M. Ridgway, S. Clark-Price, JM. Steiner, JS. Suchodolski. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract GI-5). Quote: "Proton pump inhibitors (PPI) are widely used in human and also veterinary medicine. Side-effects of PPI treatment reported in people are atrophic gastritis, gastric and esophageal cancer, and rebound hyperacidity following cessation of treatment, which has been speculated to be due to a sustained increased in circulating gastrin concentration. Moreover, long-term PPI treatment has been associated with an increased risk for osteoporosis in people. Little is known about the effect of PPI treatment on serum gastrin concentration or calcium metabolism in dogs. Eight healthy adult research dogs (4 males and 4 females) were enrolled into the study. The dogs received an average dose of 1.1 mg/kg of omeprazole orally twice daily for 15 days. ... This study shows that treatment with omeprazole for 2 weeks results in a profound and sustained increase in serum gastrin concentration in dogs. This effect is rapidly reversible after cessation of the treatment. No effect on calcium metabolism was observed. However, this study documents only the effect of short-term treatment and it is possible that the effects of long-term administration are different."
Relationship of Cerebellar Volume to Syringomyelia in the Cavalier King Charles Spaniel. TA Shaw, I McGonnell, CJ Driver, C Rusbridge, HA Volk. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract N-12). Quote: "The objective of this study was to assess the role of cerebellar volume in caudal cranial fossa overcrowding and syringomyelia. ... Forty-five small breed dogs (SB), 58 CKCS and 31 Labradors (LD) were compared. As SM is thought to be a late onset disease process, two subgroups were formed for comparison: 21 CKCS younger than 2 years with SM (group 1) and 13 CKCS older than 5 years without SM (group 2). CKCS had a larger cerebellar caudal cranial fossa percentage than the other groups (CKCS 52.19% [40.07–58.76%] vs. SB 47.81% [40.36–62.91%] and LD 41.32% [32.59–52.95%]; p o 0.001). The cerebellar brain percentage was also larger in CKCS compared to the other groups (CKCS 8.90% [6.62–11.46%] vs. SB 7.37% [5.25– 11.34%] and LD 7.23% [6.36–9.54%]; p o 0.001). Group 1 had a significantly larger cerebellar caudal cranial fossa percentage than group 2 (53.71% 1.27 vs. 49.31% 2.35, p 5 0.001) and a significantly larger cerebellar brain percentage (9.45% 0.43 vs. 8.58% 0.55, p 5 0.021). Our findings show that the CKCS has a relatively larger cerebellum than small breed dogs and Labradors and there is an association between increased cerebellar volume and SM in CKCS."
Changes over Time in Caudal Cranial Fossa Volumes and of Cerebellar Herniation in Cavalier King Charles Spaniels with Chiari-like Malformation. S. Hamilton, L. De Risio, C. Rusbridge, CJ Driver, R. Dennis, I McGonnell, HA Volk. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract N-13). Quote: "There is currently a lack of information if the morphological changes seen in CKCS with CM are progressive or non-progressive. In this retrospective study we used established measurements of cerebral volumes, foramen magnum height and cerebellar herniation length to assess if there is a significant difference between subsequent magnetic resonance (MR) imaging of the brain of the same dog. Electronic patient records were reviewed for CKCS with CM which had two separate MRI scans, which were a minimum of 3 months apart. CKCS with diseases affecting measurements were excluded. ... Volumes of the caudal cranial fossa parenchyma were analyzed as percentages of caudal cranial fossa volume and caudal cranial fossa volume was analyzed as a percentage of total cranial cavity volume. The volume of the ventricular system was recorded as a percentage of total parenchymal volume. Data was assessed for normality and the appropriate statistical test was used to compare means/medians. Twelve CKCS were included with a median scan interval of 9.5 months (3–83 months). The size of the foramen magnum increased significantly between the first and second scan ..., as did the length of cerebellar herniation ... There was no significant difference noted between the two time points in any of the other volumetric measurements ... This work could suggest that overcrowding of the caudal cranial fossa in conjunction with the movements of cerebrospinal fluid and cerebellar tissue secondary to pulse pressures created during the cardiac cycle causes pressures on the occipital bone. This leads to a resorption of the bone and therefore an increase in caudal cranial fossa and foramen magnum size allowing cerebellar herniation length to increase."
Morphometric Features of the Craniocervical Junction Region in Dogs with Suspected Chiari-like Malformation: 274 Cases (2007–2010). Dominic J. Marino. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract 95A). Quote: "Concurrent malformations of the cranio-cervical junction are commonly identified in humans with Chiari type I malformation. Recent evidence suggests such craniocervical junction abnormalities (CJAs) also occur in dogs suspected of having Chiari-like malformation (CLM). The purpose of this study was to objectively describe morphometric features of the craniocervical junction region of dogs with suspected CLM and to investigate for associations between these features and the occurrence of other malformations in this region. Magnetic resonance (MR) and computed tomographic (CT) images from 274 dogs with CLM were evaluated. Three regions of neural tissue compression were assessed: cerebellar compression (CC); ventral compression at the C1/C2 articulation, termed ‘‘medullary kinking’’ (MK); and dorsal compression (DC) at the C1/C2 articulation. A compression index (CI) was calculated for all abnormal regions for each dog. Multiple logistic regression analysis was performed (p o 0.05) to ascertain whether CI values for the different regions of compression were associated with the incidence of other cranio-cervical junction abnormalities. 68% of dogs had MK and 38% of dogs had DC. 28% of dogs also had evidence of atlanto-occipital overlapping (AOO). Breed and severity of CC were the only significant predictors of AOO (p o 0.0001 and po0.0092). 28% of suspected CLM cases have AOO as the anatomic abnormality responsible for CC. Compression index values may help differentiated subtypes of CJAs in dogs."
Medical Infrared Imaging (Thermography) of Type I Thoracolumbar Disk Disease in Chondrodystrophic Dogs. CA Loughin, DJ Marino. J Vet Intern Med 2011;--- (ACVIM 29th Ann. Vet. Med. Forum Abstract Program: Abstract 95B). Quote: "Medical infrared imaging (MII) is a non-invasive diagnostic imaging technique that measures skin surface temperature and generates thermal pattern maps based on predetermined color scales. Because skin temperature, dependent on regional perfusion, is under direct control of the sympathetic nervous system, MII provides information about the function of the autonomic nervous system. Because of recent advances in technology and lack of sedation needed to image patients, MII has potential use as a screening test for a variety of conditions that may result in autonomic dysregulation like Chiari-like malformation in dogs (CLM). The purposes of this study were to establish a MII protocol for dogs suspected of having CLM, to identify thermal imaging patterns for various regions of interest (ROI), to evaluate changes in thermal patterns and compare the results to those of MRI findings, considered the standard for diagnosing CLM in dogs. One hundred and five Cavalier King Charles Spaniel dogs with clinical signs attributable to CLM and confirmed CLM with MRI were evaluated with a complete blood count and chemistry profile, examination by a board certified surgeon/neurologist, mult-idetector CT scan of the cranio-cervical junction, whole body MRI and MII. The protocol for thermal imaging included cranial and caudal views of the body, full lateral right and left body views, dorsal views of the head and body, and right and left lateral views of the head. Thermal patterns were assessed with custom image recognition software. After each dog was imaged awake, general anesthesia was administered and the dogs re-imaged using the same protocol. MRI findings in dogs with severe or moderate cerebellar compression and cerebellar herniation were compared with MII results. The top of head and front of head ROI were 89.2% and 97.3% successful in identifying dogs with CLM. Based on these preliminary findings, MII may be a viable screening tool to detect CLM in dogs."
Cephalometric Measurements and Determination of General Skull Type of Cavalier King Charles Spaniels. M. J. Schmidt, A. C. Neumann, K. H. Amort, K. Failing, M. Kramer. Vet. Rad. & Ultra, 26; Jul/Aug 2011;52(4):436-440. Quote: "The general skull morphology of the head of the Cavalier King Charles Spaniel (CKCS) was examined and compared with cephalometric indices of brachycephalic, mesaticephalic, and dolichocephalic heads. Measurements were taken from computed tomography images. Defined landmarks for linear measurements of were identified using three-dimensional (3D) models. The calculated parameters of the CKCS were different from all parameters of mesaticephalic dogs but were the same as parameters from brachycephalic dogs. However, the CKCS had a wider braincase in relation to length than in other brachycephalic breeds. Studies of the etiology of the chiari-like malformation in the CKCS should therefore focus on brachycephalic control groups. As Chari-like malformation has only been reported in brachycephalic breeds, its etiology could be associated with a higher grade of brachycephaly, meaning a shorter longitudinal extension of the skull. This has been suggested for other breeds."
Understanding Chiari-like malformation: where are we now? Rita Gonçalves. Vet Rec Sept 2011;169:275-276. Quote: "Over recent years, numerous studies have been done to try to enhance our understanding of CM in the CKCS. Several studies used morphometric measurement methods to quantify the size of the different components of the caudal cranial fossa (CCF) and quantify the degree of mismatch between them and the CCF. Initial studies suggested that CKCS with CM/ syringo-myelia have a smaller relative caudal fossa area, compared with control dogs such as labradors (Carrera and others 2009). However, subsequent studies failed to find the same association when comparing the caudal fossa of CKCS with and without syringomyelia using three-dimensional measurement methods (Cerda-Gonzalez and others 2009, Schmidt and others 2009, Driver and others 2010a). CKCS have also been shown to have proportionally the same volume of parenchyma within the CCF as labradors (Cross and others 2009). A more recent study considered the fact that signs of syringomyelia often only shows at an older age. In this study, CKCS with CM older than five years of age (controls) were compared with CKCS with CM/syringomyelia aged two years or less. This revealed a significantly smaller CCF in CKCS with CM/syringomyelia (Driver and others 2010b). Recently it was also shown that a more marked overcrowding of the CCF due to an increased brain parenchyma volume is associated with syringomyelia (Driver and others 2010a, 2010b). A combined evaluation of these findings suggests that a combination of a reduced CCF and an increase in the parenchyma contained within the CCF most likely contribute to the pathogenesis of this complex condition. ... It is common to detect CM in dogs presenting for other problems, and a study recently published in Veterinary Record showed that the prevalence of syringomyelia in dogs considered asymptomatic by their owners was 25 per cent in dogs aged one year and 70 per cent in those aged six years or more (Parker and others 2011). This discrepancy between the imaging findings and the clinical signs poses a major difficulty when designing studies aimed at improving our knowledge about this condition. These results also have important implications in the design of a screening test procedure, which was previously recommended for dogs aged two to three years, and suggests that eliminating the disease by selective breeding may be virtually impossible. ... In a paper summarised in this issue of Veterinary Record, Upchurch and others (2011) aimed to investigate the effect of positioning of the dog’s head during MRI on the severity of CM, ... Chiari-like malformation has for a decade now been widely identified in the CKCS population but despite its high prevalence, little is still known about its pathogenesis. Further studies are necessary to increase our understanding of this condition in order to allow the development of new treatment options and improve the welfare of the CKCS affected."
Influence of head positioning on the assessment of Chiari-like malformation in Cavalier King Charles spaniels. J. J. Upchurch, I. M. McGonnell, C. J. Driver, L. Butler, H. A. Volk. Vet Rec Aug2011; doi:10.1136/vr.d4395. Quote: "Chiari-like malformation (CM) is almost omnipresent in the Cavalier King Charles spaniels (CKCS), often leading to syringomyelia (SM). Morphometric studies have produced variable results concerning relationship between the brain parenchyma within the caudal cranial fossa (CCF) and SM. The present study assesses the effect of head position, one potential confounder. Magnetic resonance images of CKCS with CM were reviewed in extended and flexed head positions. ... Fourteen CKCS were included into the study, seven dogs with CM and seven with CM/SM. ... The degree of cerebellar herniation was significantly worse in dogs with a flexed compared to an extended head position. ... Cerebellar herniation did not differ significantly between CKCS with and without SM in the extended head position. However, in the flexed head position the cerebellum herniated more caudally in CKCS with CM/SM compared to CKCS with CM alone. This highlights that the non-flexed head position may underestimate the true extent of cerebellar herniation and could explain why previous studies have missed an association with SM. ... It is well documented that flexing the head opens the CSF space of the cisterna magna and this could explain the morphometric measurements. The brainstem reduces in size to accommodate this increase in CSF space. ... When CSF space between the cerebellum and brainstem was compared in CKCS with and without SM, there was a significant increase in CSF space in CKCS with CM alone compared to those with CM/SM when head position was flexed. ... The reduced CSF space in CM/SM dogs reported in this study could explain this jet like CSF flow in dogs with CM/SM compared to those with CM alone. ... Furthermore, there is an association between head position and level of foramen magnum overcrowding. Based on these findings it may be appropriate to position patients in a more flexed head position for optimal imaging in order to identify morphologic changes more accurately. This is important to consider for imaging CKCS with CM especially when studying the pathogenesis of CM/SM. It should also be considered when taking a cisternal CSF sample as the spinal needle might be traumatic to the herniated cerebellum."Histopathological Investigation of Syringomyelia in the Cavalier King Charles Spaniel. H.Z. Hu, C. Rusbridge, F. Constantino-Casas, N. Jeffery. J Comp Path. Sept. 2011. Quote: "Syringomyelia (SM) in Cavalier King Charles spaniels (CKCSs) is identified commonly on magnetic resonance images and is sometimes associated with clinical signs of pain and cervical hyperaesthesia. However, the mechanism by which SM develops in this breed has not been fully elucidated and the associated effects on spinal cord structure have not been reported previously. The aims of this study were to describe changes found in the spinal cord of CKCSs, to compare findings between symptomatic and asymptomatic dogs and to determine whether syrinx formation was associated with tissue destruction. Anomalies of the central canal were found in all specimens and many dogs had grossly visible fluid-filled cavities within the spinal cord. Prominent microscopical findings were spongy degenerative changes associated with neuronal necrosis and Wallerian degeneration. The ependyma was discontinuous in many specimens, notably in symptomatic individuals, and there was evidence of angiogenesis and fibrous tissue proliferation around blood vessels adjacent to syrinx cavities. Compared with two different samples of the normal dog population, dogs with syrinxes had significantly less grey matter, although this decrease was associated with generalized loss of spinal cord area. Therefore, SM is associated with degenerative changes in the spinal cord and may develop through primary disruption of ependymal integrity followed by vascular hypertrophy and proliferation. Glial and fibrous proliferation appears to be associated with expression of clinical signs. ... The pathology suggested that the primary development of syringomyelia is associated with central canal dilatation and damage which is accompanied by blood vessel changes. This is an important finding because there is so much debate on how syringomyelia develops in all species."
Distribution of substance P and calcitonin gene-related peptide in the spinal cord of Cavalier King Charles Spaniels affected by symptomatic syringomyelia. Hilary Zhaoxu Hu, Clare Rusbridge, Fernando Constantino-Casas, Nick Jeffery. Research in Vet Sci; Sept 2011;doi:10.1016/j.rvsc.2011.08.012. Quote: "The causes of clinical signs associated with syringomyelia in the Cavalier King Charles Spaniel (CKCS) are incompletely understood. In this study we compared expression of two pain-related neuropeptides: substance P (SP) and calcitonin gene related peptide (CGRP), in the spinal cord dorsal horn of normal dogs with that in CKCS with and without clinical signs of syringomyelia. There was a decrease in expression of both peptides in CKCS with ‘symptomatic’ syringomyelia that was also associated with significant asymmetry in SP-I and similar, though non-significant, asymmetry in CGRP-I compared with other groups. ... This current study provides evidence to suggest that the disruption of the dorsal horn structure is a significant event in the production of clinical signs in CKCS. The spinal cord dorsal horn in symptomatic CKCS is significantly more asymmetric than that of control animals, whereas the asymptomatic CKCS have changes that are midway between control and symptomatic CKCS. This suggests the possibility that progression from mild to severe asymmetry in CKCS is associated with development of clinical signs; however such a conclusion cannot be definitively supported by this study because of the cross sectional nature of the data collected. "
Effectiveness of breeding guidelines for reducing the prevalence of syringomyelia. S. P. Knowler, A. K. McFadyen, C. Rusbridge. Vet Rec Oct 2011; doi:10.1136/vr.100062; Vet Rec Dec 2011;169:679-680. Quote: "Several toy breed dogs are predisposed to syringomyelia (SM), a spinal cord disorder, characterised by fluid-filled cavitation. SM is a complex trait with a moderately high heritability. Selective breeding against SM is confounded by its complex inheritance, its late onset nature and high prevalence in some breeds. This study investigated the early outcome of existing SM breeding guidelines. Six hundred and forty-three dogs, 550 Cavalier King Charles spaniels (CKCS) and 93 Griffon Bruxellois (GB), were identified as having either one (454 dogs) or both parents (189 dogs) with MRI-determined SM status. Offspring without SM were more common when the parents were both clear of SM (SM-free; CKCS 70 per cent, GB 73 per cent). Conversely, offspring with SM were more likely when both parents had SM (SM-affected; CKCS 92 per cent, GB 100 per cent). A mating of one SM-free parent with an SM-affected parent was risky for SM affectedness with 77 per cent of CKCS and 46 per cent of GB offspring being SM-affected. ... This paper serves to report the early outcome of using the 2006 breeding guidelines for dogs contributing to a genome project and whose pedigrees were known. The study suggested that SM-free offspring were more likely if both parents were SM-free and SM-affected offspring were more likely if both parents had SM. There was a trend that older SM-free dogs (*A) only resulted when at least one parent was *A. This finding seems logical but since *A and A grade dogs are in a minority it is problematic for breeders to select SM-free dogs especially when the SM status of the dog can alter with age. Often, the true SM status may not be known until after the dog is used for breeding. In 2010, there were 2136 CKCS litters registered with the UK kennel club (8095 puppies). Of these, 33 per cent had a sire aged younger than 2.5 years on the day of mating and 36 per cent had a dam younger than 2.5 years on the day of mating. This translates as 55 per cent of the KC registered CKCS puppies having one parent younger than 2.5 years and 14 per cent having both (Grahame Ford, personal communication). Thus, a recommendation that only A or *A grade parents be used is unlikely to be practical for breeders. If a younger SM-free dog (C grade) is mated with an older dog (A grade), then there is greater risk for SM than with two A grade parents. The data in the study (Tables 3 and 4) suggested that 63 per cent (12/19) of offspring were SM-free from A or*AxC parents. This is likely to be an overestimation of the proportion of SM-free dogs since these figures include C grade offspring, which may develop SM as they become older. However, it could be argued that a recommendation to include at least one A grade dog in any proposed mating is a reasonable, practical alternative since it allows breeders to use their younger dogs. However, a far better proposal for prevention of SM and maintaining genetic diversity is a proposed mate select programme using estimated breeding values (EBV). ... The most controversial part of the 2006 breeding recommendations was that it permitted older clinically asymptomatic SM-affected dogs to be bred to older SM-free dogs. This was because there were only a few A grade dogs identified when the breeding guidelines were first proposed and overuse of these might limit genetic diversity, reducing the effective population size. This investigation showed that a proportion of the offspring from such a cross can be SM-free, however, in the CKCS, the number of SM-affected dogs was far greater than SM-free dogs (77 per cent SM-affected). Moreover, where these offspring had siblings, the ratio of SM-free to SM-affected was 1:1 compared with 3.5:1 for *A or Ax*A or A parents or 1:1.7 for D or ExU parents (Knowler and Rusbridge, unpublished data). It is debatable whether it is ethical to knowingly breed a dog with an inherited disease especially when the majority of the offspring may be destined for the pet-owning public, and this study suggested that it is not advisable to use SM-affected dogs for breeding. However, if the prevalence of SM is as high as 70 per cent in the CKCS (Parker and others 2011), this will have dire consequences for the effective population size of the breed. Again it is hoped that using an EBV mate select programme may allow safer parental crosses, maintaining genetic diversity while decreasing the number of SM-affected offspring. One problem noted with the 2006 breeding guidelines was that if the dog was deemed asymptomatic but SM-affected when first scanned over 2.5 years old it was attributed a grade D status. However, in some cases it was suspected, due to the size of the syrinx, that if the dog had been scanned when younger then the syrinx would have been apparent, in other words, the dog was actually an E grade. It was also possible that some dogs may have been clinically affected (ie, an F grade) as the early behavioural signs of pain from SM and/or CM can be subtle and/or intermittent and may not be detected in a routine clinical examination. In addition, some breeders fail to recognise or acknowledge clinical signs of SM and/or CM. Since the aim of the guidelines is to reduce the incidence of early onset and clinical SM, a future recommendation is that a D status (or equivalent) will only be appropriate if the dog was first proved by MRI to be SM-free before 2.5 years of age. One encouraging observation was that the proportion of grade E (SM-affected younger than 2.5 years of age) dropped from an average of 15 dogs per year in years 2004 to 2006 to 11 dogs per year in years 2007 to 2009, that is, the breeding guidelines may be achieving the goal of reducing the risk of early onset SM, however, this hypothesis would be needed to be tested in a more vigorous study. ... In conclusion, the results from this study suggest that it is appropriate to continue using the breeding guidelines for both the CKCS and GB until a more robust system based on EBV or genetic testing is available. The following modifications are suggested but it should be realised that these are the recommendations that are based on limited data and consequently should be subjected to further prospective vigorous study: To increase the number of SM-free offspring, at least one parent should be ascertained to be SM-free by MRI as a young adult. In ideal circumstances, both parents would be SM-free. According to the study by Parker and others (2011), the optimum age for this early MRI screening is 36 months. If an SM-affected dog is used, for example, to preserve desirable traits or to increase genetic diversity then ideally the chosen mate would either be selected on the basis of its EBV and/or would be an older SM-free dog (five years or older). The offspring of the proposed mating should also be MRI scanned and ideally bred to older SM-free dogs. The SM status of the dog when at least five years old should be established. SM has a complex inheritance and an EBV mate select programme should allow breeders to select safer breeding combinations. To ensure success, the programme requires a substantial collection of accurate populationwide data. Consequently, all breeding dogs from breeds susceptible to CM and SM should be MRI screened and these results should be submitted to a central source. Pedigree and clinical history from dogs presenting with clinical signs of CM and/or SM should also be submitted to this central system. ‘D’ status (or equivalent) will only be appropriate if the dog was first proved to be SM-free before 36 months of age. Future breeding recommendations should also take account of dogs with CCD less than 2 mm. ..."
Dorsolateral spinal cord compression at the C2-C3 junction in two Cavalier King Charles spaniels. K. P. Harris, T. C. Saveraid, and S. Rodenas. Vet Rec Oct 2011;169(16):416. Quote: "Due to the high incidence of Chiari-like malformation (CM) and syringomyelia (SM) in Cavalier King Charles spaniels (CKCS), the presentation of this breed with a history of apparent neck pain often prompts an early suspicion for CM-SM. Conversely, CM-SM findings upon MRI have been reported in many asymptomatic CKCS and thus other differentials for neck pain such as vertebral trauma, meningioencephalomyelitis or myelocompression must be exhaustively excluded. Cervical spondylomyelopathy (CSM), also referred to as cervical vertebral malformation-malarticulation syndrome, cervical vertebral stenotic myelopathy and wobbler syndrome among other terms, is a common multifactorial neurological disorder affecting mainly large/giant breed dogs. Cases of CSM have been broadly classified by their mechanism of spinal cord and/or nerve root compression as either disc-associated (DA-CSM) or osseous-associated (OA-CSM). This short communication describes dorsolateral compressive lesions of the spinal cord at the C2-C3 junction, similar to those described in giant breed dogs with OA-CSM, in two CKCS with concurrent CM, being evaluated with MRI for neck pain. To the author's knowledge, this is the first report of such MRI findings in this breed. In case 1, a 13.9 kg two-year-old male neutered CKCS presented with a three-month history of intermittent periods of apparent discomfort manifested as very abrupt rising from rest. Two weeks earlier, the owner had observed an isolated episode of ataxia during which the dog fell to the left, had a left-sided head tilt and facial twitching. The dog remained responsive to the owner throughout and returned to normal within 30 minutes. The owner also reported that the dog frequently scratched at one ear (the side unknown). Neurological and otoscopic examination revealed no abnormalities. Moderate to severe hyperaesthesia was evident upon manipulation of the cervical spine."
Use of the loop diuretic torsemide in three dogs with advanced heart failure. Mark A. Oyama, Gordon D. Peddle , Caryn A. Reynolds, and Gretchen E. Singletary. J Vet Cardio; Oct 2011; doi:10.1016/j.jvc.2011.10.001. Quote: "Diuretics are a mainstay of therapy in dogs with heart failure. In dogs with advanced heart failure, moderate to high doses of loop diuretics such as furosemide are used with diminishing effects as profound activation of neuroendocrine systems promote signs of congestive heart failure. The loop diuretic torsemide has several characteristics that make it suitable for treatment of advanced heart failure including longer half-life, increased potency of diuretic action, and anti-aldosterone effects. ... This case series describes 3 dogs [including a 12 year-old cavalier King Charles spaniel] with advanced heart disease that despite treatment with multiple cardiac medications and moderate to high doses of furosemide experienced frequently recurring episodes of CHF. ... In each dog, replacement of furosemide with a torsemide dose, in terms of mg/kg, at one-tenth to one-thirteenth of the daily furosemide dose were associated with apparent resolution of CHF for relatively long durations of time. We speculate that when switching to torsemide, restoration of diuretic response was the most likely cause of this observation. In these and other cases managed by the authors, pet owners report notable increases in their dog’s diuresis and water consumption following institution of torsemide. In a small prospective blinded cross-over study,13 dogs with heart failure experienced significantly higher serum albumin and significantly lower urine specific gravity when receiving torsemide as compared to furosemide, suggesting that torsemide is associated with a relatively greater diuretic response. ... Torsemide’s safety and superior efficacy have previously been established in human patients with CHF. ... The restoration of diuretic responsiveness and the accompanying volume depletion that follows torsemide administration might increase risk for renal insufficiency, and care should be taken to limit or reduce administration of concurrent diuretics such as hydrochlorothiazide and to closely monitor renal function when administering torsemide. The authors also recommend that owners of dogs receiving torsemide closely monitor their dog’s urine production, water consumption, and appetite. ... Torsemide has several attractive pharmacologic properties that might aid in the long-term treatment of canine heart disease. Clinical guidelines or recommendations involving torsemide should follow from prospective clinical trials demonstrating the long-term safety and potential superiority of torsemide over furosemide and other commonly used diuretics."
Distribution of syringomyelia along the entire spinal cord in clinically affected Cavalier King Charles Spaniels. Shenja Loderstedt, Livia Benigni, Kate Chandler, Jacqueline M. Cardwell, Clare Rusbridge, Christopher R. Lamb, Holger A. Volk. Vet J Dec 2011;190:359–363. Quote: "The objective of the present study was to define the anatomic distribution of SM in CKCS clinically affected by CM/SM. Our hypotheses were that in dogs with SM, (1)SM is present at multiple locations throughout the whole spinal cord; (2) the prevalence of SM is greatest in the cervical spine versus other regions; (3) the presence of SM in the cervical spinal cord is associated with the presence of SM in further caudal spinal cord regions; (4) the maximal syrinx size in each patient is in the cervical spine, and (5) there is a positive association between patient age and total syrinx size. ... 49 dogs were included in the present study. The median age of the dogs included in the study was 5 years (1.2–10.8 years). CM was present in all patients. ... All dogs in the present study were clinically affected. ... However, in our study SM was absent in 25% of dogs with clinical signs. ... There was no evidence of SM on MRI in 12/49 (25%) dogs. In all dogs with MRI evidence of SM (37/49; 75%), SM was present within the C1–C4 region (Figs. 2 and 3). Of those dogs with SM within C1–C4 region, 76% (28/37) also had SM within the C5–T1 and/ or T2–L2 regions, but only 49% (18/37) had SM within the L3–L7 region. ... The results of our investigation show that imaging only the cervical spine in clinically affected CKCSs is likely to underestimate the total syrinx size and the anatomical distribution of SM. The presence of cervical SM in all dogs with MRI evidence of SM could however justify the restricted imaging under screening purposes. ... The results of our study showed syrinx formation in all regions of the spinal cord with no significant differences of Sx between the cervical, cervicothoracic and thoracolumbar regions, but significantly smaller Sx in the caudolumbar spinal region. ... In our study Smax was most often seen within the C1–C4 region and, interestingly, also over T2–L2 vertebral bodies. ... We found that the severity of SM was positively correlated with patient age. This is consistent with previous studies indicating that CKCS with SM were significantly older than dogs without SM (Couturier et al., 2008). It seems likely therefore, that SM is a progressive disease in dogs. ... Conclusions: There is a very high potential for CKCS with clinical signs of CM/SM to develop SM in more than one spinal cord region. Diagnostic imaging limited to the cervical spine in clinically affected CKCS is likely to underestimate the degree and severity of SM. It can be hypothesised that SM has a progressive nature in CKCS, which requires further characterisation."
Can breeding strategies modify or eliminate the syringomyelia phenotype? Colin J. Driver, Holger A. Volk. Vet Rec; Dec 2011;169:679-680.
Syringosubarachnoid shunt as a management for syringohydromyelia in dogs. L. Motta, G. C. Skerritt. J.Sm.An.Prac. Apr.2012; 53(4):205-212. Quote: "Objective: To evaluate retrospectively the efficacy of syringosubarachnoid shunt for the management of syringohydromyelia/syringomyelia. (The aim of the surgical procedures would be to decompress the neural tissue, to re-establish CSF flow and so decrease the syrinx size. In consequence, there may be reduction of neuropathic pain and spinal cord function may be promoted, providing that there has not been significant damage to the dorsal grey column and/or spinothalamic tracts.) (The S-S shunting drains the syrinx fluid into the subarachnoid space where the usual CSF circulation and absorption mechanisms exist. This reduces the syrinx size and eases the clinical signs associated with SHM/SM.) Methods: Eleven dogs (9 cavalier King Charles spaniels and 2 Yorkshire terriers) diagnosed with syringohydromyelia/syringomyelia by magnetic resonance imaging associated with Chiari-like malformation underwent placement of a syringosubarachnoid shunt at the cervical (nine dogs) or lumbar (two dogs) spinal cord. In one dog, a suboccipital decompression (foramen magnum decompression) was performed 4 months before inserting a syringosubarachnoid shunt (A silicone veterinary ocular lavage catheter by Smiths Medical was used to create the shunt.) (In nine cases, this was carried out at C3-C4 and in the remaining two cases at L1-L2). All dogs were evaluated neurologically a few hours after surgery, 2 weeks and 6 months postoperatively. Retrospectively, cases were assigned a preoperative and postoperative pain score. Results: There were no intra- or peri-operative complications. One dog (9%) was euthanased 5 weeks after surgery. Progressive neurological improvement was observed in nine dogs (81·8%) 2 weeks and 6 months postoperatively. No clinical improvement was seen in another dog (9%). One dog (9%) had replacement of the syringosubarachnoid shunt. Seven dogs (63·6%) were still alive 1 to 4 years (mean, 2·6 years) after surgery. Clinical Significance: Placement of a syringosubarachnoid shunt in the presence of a sufficiently large syrinx appears to be beneficial in dogs with Chiari-like malformation and associated syringohydromyelia/syringomyelia. (This small retrospective clinical study showed that S-S shunting is a safe and relatively effective surgical technique that may improve the neurological signs and the quality of life of dogs affected by CM and associated SHM/SM. Postoperative complications or lack of clinical improvement may occur in a small number of cases and a secondary surgery may be needed. This study also suggests that the S-S shunt may lead to a satisfactory outcome in dogs where the FMD technique has failed. Comparisons between different surgical techniques are needed to create objective criteria that may suggest which procedure will produce the best surgical results.)"
Increase in Cerebellar Volume in Cavalier King Charles Spaniels with Chiari-like Malformation and Its Role in the Development of Syringomyelia. Thomas A. Shaw, Imelda M. McGonnell, Colin J. Driver, Clare Rusbridge, Holger A. Volk. PLoS ONE; April 2012; 7(4):e33660. http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033660 Quote: "Previous research in Cavalier King Charles Spaniels (CKCS) has found that Chiari-like malformation and syringomyelia (CM/SM) are associated with a volume mismatch between the caudal cranial fossa (CCF) and the brain parenchyma contained within. The objectives of this study were to i) compare cerebellar volume in CKCS (a “high risk’ group which frequently develops CM/SM), small breed dogs (medium risk – occasionally develop CM/SM), and Labradors (low risk – CM/SM not reported); ii) evaluate a possible association between increased cerebellar volume and CM/SM in CKCS; iii) investigate the relationship between increased cerebellar volume and crowding of the cerebellum in the caudal part of the CCF (i.e. the region of the foramen magnum). Volumes of three-dimensional, magnetic resonance imaging derived models of the CCF and cerebellum were obtained from 75 CKCS, 44 small breed dogs, and 31 Labradors. As SM is thought to be a late onset disease process, two subgroups were formed for comparison: 18 CKCS younger than 2 years with SM (CM/SM group) and 13 CKCS older than 5 years without SM (CM group). Relative cerebellar volume was defined as the volume of the cerebellum divided by the total volume of brain parenchyma. ... Our results show that the cerebellum is proportionately larger in CKCS (and a similar brainstem volume) when compared to Labradors and small breed dogs and also larger in young CKCS with CM and SM than in older CKCS with CM alone. ... Furthermore, the degree of cerebellar crowding in the caudal CCF is correlated with increased volume of the cerebellum in CKCS and this is not seen in small breed dogs or Labradors. These findings have implications for the understanding of the pathological mechanisms of CM/SM, and support the hypothesis that it is a multifactorial disease process governed by increased cerebellar volume and failure of the CCF to reach a commensurate size. ... In this study we found that CKCS under the age of 2 with SM (the CM/SM group) have an increased cerebellar volume when compared to CKCS over the age of 5 without SM. ... In CKCS there is an association between increased cerebellar volume and SM. These findings have implications for the understanding of the pathological mechanisms of CM/SM, and support the hypothesis that it is a multifactorial disease process governed by increased cerebellar volume and failure of the CCF to reach a commensurate size."
