Syringomyelia (SM) and the
Cavalier King Charles Spaniel

• IN SHORT
• IN DEPTH
• CM - OH - COMS
• What SM Is
• Symptoms
• Diagnosis
• - MRIs
• - CTs
• - thermography
• - ultrasound
• - BAER
• MRI Clinics
• Progression
• Treatment
• - drugs
• - alternative care
• - surgery
• - soundwave therapy
• Current Research
• Seminars
• Breeders' Responsibilities
• What You Can Do
• Related Links
• Veterinary Resources

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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 as many as 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... 

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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 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. 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...

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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 $900.00 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...

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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), 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...

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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 by buying 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.

4Donate to Rupert's Fund, which pays for MRIs of older dogs, to aid the Syringomyelia Genome Research Project.

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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Get this book! For the love of Ollie

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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, and there remains a lack of data about the prevalence and anatomical distribution of SM along the spinal cord.

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 up to 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.

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 Bichon Frisé, Boston terrier, Brussels Griffon (Griffon Bruxellois), bull terrier, Chihuahua, French bulldog, Havanese, King Charles spaniel (the English toy spaniel), Maltese terrier, minature dachshunds, minature and toy poodles, Papillon, Pomeranian, Pugs, Shih Tzu, Staffordshire bull terrier, and the Yorkshire terrier.

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Chiari-like malformation (CM or CLM) -- Occipital hypoplasia (OH) -- Caudal occipital malformation syndrome (COMS)

These three terms have been used to identify the malformation believed to play a role in the cause of syringomyelia.  Although they technically mean different things, they often are used interchangeably.  Some neurologists prefer one term over the others. However, researchers meeting at the International Conference on Syringomyelia at the Royal Veterinary College in London in November 2006 agreed upon the use of Chiari-like malformation (CM or CLM) to describe the malformation found in the Cavalier and to a lesser extent in a few other breeds.

4Chiari-like malformation (CM or CLM): The foramen magnum is a hole in the back of the skull, leading to the spinal cord. In the Cavalier breed, the back half of the skull -- the occipital bone -- reportedly* is smaller than the typical toy dog breed. This condition is called Chiari-like malformation, named after a similar condition in humans, discovered by Dr. Hans Chiari. Chiari-like malformation is defined as "decreased caudal fossa volume with caudal descent of the cerebellum, and often the brainstem, into or though the foramen magnum."  See Karen Kennedy's** Understanding Canine Chiari Malformation and Syrningomyelia for diagrams of the occipital bone and foramen magnum.

*There is some dispute about this finding. See the 2009 and 2010 UK study reports below.

**Karen Kennedy, RTMR, MappSc, is a magnetic resonance imaging specialist with The London Health Sciences Centre, London, Ontario, Canada.

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, of the Stone Lion Veterinary Centre in London, England, a leading investigator into SM, has described the three "classic features" of occipital 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."

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.

4Occipital 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.

4Caudal 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.

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.

4Is CM the real culprit? 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 -- of the volume of the total cranial cavity did not differ significantly between CKCS 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 brachy-cephalic 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".

In a 2010 UK study report in the Journal of Small Animal Practice (JSAP), Colin J. Driver, 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.

As noted above, the current definition of "Chiari-like malformation" is "decreased caudal fossa volume with caudal descent of the cerebellum, and often the brainstem, into or though the foramen magnum." However, based upon these 2009 and 2010 studies of brain size, "caudal fossa volume" may not the problem. Instead, the oversized cerebellum may be the culprit, or a combination of the two.

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 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.

This 2010 JSAP study helps to explain that CM may not be the cause of SM, and that a Cavalier can have CM without necessarily also having SM.  The key element in having SM may be a combination of the presence of CM -- a likely condition in most all Cavaliers -- along with the disproportionately higher volume of hindbrain.

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.

If the 2009 German and the 2009 and 2010 UK studies are on the right track, then we may have to either re-define "Chiari-like malformation" or use another term to describe the disorder, since the "malformation" may not be of the skull, but of the brain. A re-definition could be "increased cerebellar parenchyma volume with caudal descent of the cerebellum, and often the brainstem, into or though the foramen magnum."

Based upon these most recent reports, it appears unlikely that CM is the cause of SM.  While CM is very widespread in the Cavalier breed, and CM logically leads to syringomyelia because it looks like it ought to, the apparent severity of CM in the CKCS does not always accurately predict the presence or future presence of SM in the dog.  The UK studies in 2009 and 2010 suggest that CM may not be the cause of SM at all, and that, instead, a disproportionately large hind portion of the brain may be a necessary element.

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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.

4Role of the ventricle system: 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.

In the 2010 JSAP UK study (see, also 2009 ECVN abstract) and the 2010 BSAVA UK study, both led by Colin Driver, the researchers compared the dimensions of the ventricle cavities and found that their volumes had a direct correlation with the width of the syrinx. They concluded that this association supports the theory that the development of syrinxes are the result of CSF disturbances.

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.

(Note: There are other forms of syringomyelia in canines: (a) spinal dysraphism or spinal dysplasia, 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 forming completely in the womb; and (b) SM caused by tumors, cysts, or trauma; and (c) possible SM-like neurological symptoms due to Chiari-like malformation in brachycephalic breeds.  None are discussed here.)

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.

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Symptoms

The number of diagnosed cases in Cavaliers has increased dramatically since 2000. 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 have SM without displaying any outward symptoms at all.  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).

Symptoms may vary widely among different dogs, but the earliest sign often is that the dog feels a sensitivity in its neck area, causing 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.

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.  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 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.

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.

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.

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.  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.

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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.

-- 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

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."

-- ultrasound

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."

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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.

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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.

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 (scan, anesthesia and interpretation) for $450.00 per dog. The conditions for this low fee are: (a) the owner brings a current blood test report (no more than a month old); (b) there are no complicating health issues, such as heart problems; and (c) the owner also pays a $200.00 visit charge with the Neurology Service, which covers an evaluation before the scan and a follow-up conference to discuss the findings, treatment options, etc. Contact Dr. Schubert directly at telephone 352-392-2235 or his technician, Amy Reynolds, email Reynoldsa@vetmed.ufl.edu Advise them that you want to schedule a screening, so that they may coordinate with the anesthesia and radiology departments and thereby avoid extra costs.

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

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 mini-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.

4CHARLOTTE, NC: Dr. Peter J. Brofman, board certified neurologist at Carolina Veterinary Specialists, offers reduced rate of $1,000.00 for MRIs for breeding screening protocols only. The fee includes the MRI and anesthesia. The MRI is a 1.5T unit and is available for screenings Mondays through Fridays. Pre-anesthetic is not included in the fee. Carolina Veterinary Specialties is located at 2225 Township Road, Charlotte, North Carolina 28273, telephone 704-504-9608, email pbrofman@carolinavet.com, website www.carolinavet.com

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.

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

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.

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.

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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.

-- 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), and aspirin, 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.

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.

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, 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, as it may increase the risk of stomach cancer. 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.

Researchers have been examining the effects of cimetidine (Tagamet, Zatic), 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.

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-- 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.

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-- surgery

Surgery to allow the cerebrospinal fluid to flow normally may be necessary to reduce the pain and deterioration.  Surgery is recommended if there is significant pain or a deteriorating condition.  It usually is successful in significantly reducing the pain and improving the neurological deficits.  Neurologists experienced with CM and SM in Cavaliers have found that early surgical treatment is more successful than waiting and considering it as a last resort, and that the longer the dog has been in pain, the less likely it will recover.

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 as many as half 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.  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.

--- 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 Auburn University 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.

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."

-- other surgical techniques

Another form of surgery, performed by veterinary neurosurgeon Geoffrey Skerritt, BVSc, MIBiol ,CBiol, DipECVN, FRCVS, in the United Kingdom, and others, involves inserting a shunt, rather than removing the supraoccipital bone or a portion of the atlas.  He is said to prefer the shunt because it reduces the higher risk of nerve damage and blood loss in decompression surgery, and it lessens the possibility of the cerebellum continuing to herniate.  Mr. Skerritt may be contacted at ChesterGates Animal Referral Hospital, Telford Court, ChesterGates, Chester, UK, CH1 6LT, telephone 01244 853823, email GCSkerritt@aol.com.

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."   

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-- 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

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Current Research

4June 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.

4June 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.

4June 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.

4May 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 additonal mapping of the locus is under way.

4May 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.

4May 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."

4April 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.

4March 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.

4March 2010: Contribute to RUPERT’S FUND. RUPERT’S FUND is a project to help fund MRI scans of Cavaliers aged 6 years and older. These scans are a critical part of the Syringomyelia Genome Research Project, which is nearing completion. Please help these senior dogs help the breed’s future! As little as £10.00 makes a difference.

Rupert’s 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.

4February 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.

4October 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.

They reported at the 2009 ACVS Symposium:

"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."

4August 2009: UK researchers find no significant difference in spinal canal widths of 59 SM and 19 non-SM Cavaliers.

4August 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.  Craniosynostosis is the premature closure of the skull's growth plate.

4May 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.

4April 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.

4April 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.

4March 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."

4January 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."

4November 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).

4November 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.

4October 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.

4October 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.uk

4October 2008: Dr. Blott's Preliminary Report on SM Gene Research.  Dr. Sarah Blott, of UK's Animal Health Trust and who is leading the research to identify the genes controlling SM, 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."

4May 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

4May 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.uk

4April 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).

4March 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.

4March 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

4January 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."

4November 2007: Dr. Rusbridge's Syringomyelia News Winter 2007 Research Update

4November 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.

4October 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."

4October 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.

4September 2007: Dr. Rusbridge's Syringomyelia News Autumn 2007 Research Update

4June 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."

4May 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!

4Dr. Rusbridge's Syringomyelia News 2007 Research Update 

4Geneticist 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.

4June 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.

4Progression 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.edu

42005 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."

4April 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

4April 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)

4March 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.ca

4Post-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.

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Syringomyelia Seminars

4International 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. Summaries of presentations by Clare Rusbridge, Dominic Marino, Graham Flint, Guy Rouleau, and Sarah Blott are available at syringomyelia2007.org/symposium07_supplement.pdf.  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/4311456

4Syringomyelia 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.

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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.

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What You Can Do

4Donate by buying 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.

4Donate to Rupert's Fund, which pays for MRIs of older dogs, to aid the Syringomyelia Genome Research Project.

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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Related Links

 SM Breeding Protocol
Board Certified Veterinary Neurologists
MRI Screening Protocol
Estimated Breeding Values
Primary Secretory Otitis Media (PSOM)
Questions for Cavalier Breeders
Canine Health Testing Clinics

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Dr. Clare Rusbridge:
Dr. Rusbridge's Comprehensive Website
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

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A website devoted to syringomyelia in Cavaliers is Karlin Lillington's SM.CavalierTalk.com

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Two SM support email groups for owners of dogs with SM are Yahoo! Group: Arnold Chiari Dogs
and Yahoo! Group: CKCS SM-support

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Two SM email discussion groups are Yahoo! Group: CKCS-SM
and Karlin Lillington's CavalierTalk: SM and MVD Cavaliers Forum.

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A website and a book about a Cavalier diagnosed with syringomyelia is at For the love of Ollie.

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Cavalier Owners' Blogs:
Ella's Battle With Syringomyelia
Riley's Beating Syringomyelia
Abbey our CKCS and her family's Syringomyelia Journey
Lucy Magic Sky

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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

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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

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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.

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.

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.

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.

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). 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."

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."

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."

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