Syringomyelia (SM) and the
Cavalier King Charles Spaniel
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IN SHORT - IN DEPTH
- CM - OH - COMS
- Chiari-like malformation
- - CM research history
- -CM recent findings
- - pain due to CM
- What SM Is
- Symptoms
- Diagnosis
- - MRIs
- - CTs
- - thermography
- - ultrasound
- - BAER
- MRI Clinics
- DNA Testing
- Progression
- Treatment
- - drugs
- - alternative care
- - surgery
- - soundwave therapy
- Seminars
- Breeders' Responsibilities
- What You Can Do
- Research News
- Related Links
- SM in Other Breeds
- Veterinary Resources
- Page 2 of Syringomyelia
IN SHORT:
Syringomyelia (SM) is an extremely serious condition in which fluid-filled cavities develop within the spinal cord near the brain. It is also known as "neck scratcher's disease", because one of its common signs is scratching in the air near the neck.
The back half of the cavalier King Charles spaniel’s skull typically may be too small to accommodate all of the brain’s cerebellum, which may also be too large, and so it squeezes through the foramen magnum – the hole at the back of the skull – partially blocking the flow of cerebrospinal fluid (CSF) down the spinal cord. The variable pressure created by the abnormal flow of CSF is believed to create the SM cavities – called syrinx – in the spinal cord.
SM is rare in most breeds but has become very widespread in cavalier King Charles spaniels. The number of diagnosed cases in cavaliers has increased dramatically since 2000. Researchers estimate that up to 95% of CKCSs have Chiari-like malformation (CM or CLM) – also known as caudal occipital malformation syndrome (COMS) or occipital hypoplasia (OH), the skull bone malformation present in all cases and believed to be at least part of the cause of syringomyelia – and that more than 50% of cavaliers have SM. The severity and extent of syringomyelia also appear to get worse in each succeeding generation of cavaliers. It is worldwide in scope and not limited to any country, breeding line, or kennel, and experts report that it is believed to be inherited in the cavalier. More►
Symptoms
SM seldom can be detected in young puppies, as symptoms of it usually are not evident before the age of six months or years later.
Pain is the most important clinical sign of the disorder. Symptoms
may vary widely among different dogs, but the earliest sign often is that
the dog feels a hypersensitivity in its neck area, causing in some an uncontrollable
urge to scratch at its neck and shoulders. Then usually follows severe pain
around its head, neck, and shoulders, causing it yelp or scream.
Click here
or the YouTube logo to see videos of cavaliers with SM symptoms. As the
disease progresses, it destroys portions of the cavalier's spinal cord, and
is so painful that the affected dog may contort its neck and even sleep and
eat only with its head held high. The dog's legs may become progressively
weaker, so that walking becomes increasingly difficult. Some dogs
deteriorate to the point of paralysis. More►
Diagnosis
The only accurate way of diagnosing the disease is through the use of magnetic resonance imaging (MRI) scanning, an extremely costly procedure. The MRI allows the veterinary neurologist to study the spine for the presence of any abnormality which might obstruct the flow of the cerebrospinal fluid. Accurate MRI results require that the dog be anesthetized. Clinic charges for MRI examinations of canines have been known to vary from a rare discounted rate of $600.00 to over $2,000.00.
The names and locations of veterinary neurologists who are board certified by the American College of Veterinary Internal Medicine (ACVIM) are on our Neurologists webpage.
Another disorder common to cavaliers and with symptoms similar to SM is Primary Secretory Otitis Media (PSOM), which is a highly viscous mucus plug which fills the middle ear and causes the tympanic membrane to bulge. Because the pain and other sensations in the head and neck areas, resulting from PSOM, are so similar to symptoms due to SM, the possibility that the cavalier has PSOM and not SM should be determined before diagnosing SM. More►
Treatment
Treatment options for SM are very limited. Before the disease
progresses to its severe form, the use of cortisteroids, such as
prednisolone, or non-steroidal anti-inflammatory drugs (NSAIDs, such as
Rimadyl and
Metacam) may relieve the symptoms but not the deterioration.
Cortisteroids have serious side effects, such as weight, gait, and skin
changes, and harmful suppression of the immune system. Long term use
of these drugs is not advised.
Anticonvulsants, such as gabapentin (Neurontin, Gabarone), have been successful in some more severe cases, but they may be very expensive. Pregabalin (Lyrica), amitriptyline (Elavil, Tryptizol, Laroxyl, Sarotex), and oral opioids (pethidine or methadone) are alternatives. Methylsulfonylmethane (MSM) is recommended by some veterinary neurologists as a dietary supplement.
Drugs which reduce the production of cerebrospinal fluid, including proton pump inhibitors such as omeprazole (Prilosec), and the diuretic, furosemide (Lasix, Diuride, Frudix, Frusemide), and spironolactone (Aldactone), may be useful, but clinical data on their use and effectiveness is lacking. Carbonic anhydrase inhibitors, such as acetazolamide (Diamox) also serve to decrease the flow of cerebrospinal fluid, but their adverse side effects of abdominal pain, lethargy, and weakness limit long term use.
Surgery to allow the cerebrospinal fluid to flow normally may be necessary to reduce the pain and deterioration. However, such surgeries are technically difficult and should be performed only by specialists. In some cases a shunt is installed. Although surgery often is successful, it is very expensive, and many dogs either have a recurrence of the disease or still show signs of pain and scratching. The most frequent reason for recurrence reportedly is the development of post-operative scar tissue. At least one neurologist has been inserting titanium mesh, in an effort to prevent such scar tissue from building up. More►
Breeders' Responsibilities
SM has a tendency to be more severe in each subsequent generation, and with an earlier onset. Breeders should follow the SM Breeding Protocol. The aim of the breeding protocol is to reduce the incidence of symptomatic syringomyelia in the cavalier breed, and not to create litters of puppies guaranteed not to have SM. The chance of producing an affected dog cannot be predicted without knowing the inheritance.
What You Can Do
4Donate to Rupert's Fund, which pays for MRIs of older dogs, to aid the Syringomyelia Genome Research Project.
4Donate by buying the book, For the love of Ollie.
4Participate in the Syringomyelia Cavalier Collection Scheme. Read about it here.
4Donate funds to cavalier SM DNA research; payee "Syringomyelia DNA Research", address: Stone Lion Veterinary Hospital, Goddard Veterinary Group, 41 High Street Wimbledon Common London SW19 5AU, email neurovet@virginmedia.com, telephone: 020 8946 4228, fax: 020 8944 0871. Read about it here.
4Send MRI scans of cavaliers 5 years old or older and which do not have SM, along with MRIs of those dogs' family members, to Dr. Clare Rusbridge at neurovet@virginmedia.com Read about it here.
4Donate to the Cavalier Foetal Tissue Research Project. Also, contact Sheena Stevens in Devon, UK, telephone 01884 821080, email Kilnshena@hotmail.com, about sending aborted cavalier fetuses and deceased young puppies (that have died for any reason) to Dr. Imelda McGonnell at The Royal Veterinary College for research. Read about it here.
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Give to Rupert's Fund! |
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IN DEPTH:
Syringomyelia (SM -- also known as syrinx and hydromyelia, and
occasionally mis-identified as Arnold Chiari malformation) is a condition of
the development of fluid-filled cavities in the spinal cord, which is
believed by researchers to be due to abnormal
flow of cerebrospinal fluid (CSF) between the brain and the spinal cord
through the foramen magnum at the base of the skull.
Technically, hydromyelia is a dilatation of the central canal within the spinal cord, and syringomyelia is the cavitation of the spinal cord parenchyma. Combined, they are referred to either as syringo-hydromyelia (SHM) or hydro-syringomyelia. The disease is referred to generally as syringomyelia and SM herein. This condition is similar, but not identical, to Arnold Chiari Type I Syndrome in humans.
Syringomyelia also may be described as syringomyelia secondary to Chiari-like malformation (CM or CLM). CM is also referred to as occipital hypoplasia (OH) or caudal occipital malformation syndrome (COMS). The full relationship between CM and the development of SM is not fully understood.
SM is rare in most breeds but has become very widespread in cavalier King Charles spaniels. Some researchers estimate that as many as 95% of CKCSs have Chiari-like malformation (CM or CLM), the skull bone malformation believed to be a part of the cause of syringomyelia, and that more than 50% of cavaliers have SM.* It is worldwide in scope and not limited to any country, breeding line, or kennel, and experts report that it is believed to be inherited in the cavalier King Charles spaniel. CM is so widespread in the cavalier that it may be an inherent part of the CKCS's breed standard.
* A 2011 study of 555 UK cavaliers, reported by their owners to be symptom-less, found 25% of one year olds and 70% of 6+ year olds had SM.
The severity and extent of syringomyelia also appear to get worse in each succeeding generation of cavaliers. Other breeds known to be affected to a lesser extent include the Affenpinscher, Bichon Frisé, Boston terrier, Brussels Griffon (Griffon Bruxellois), bull terrier, Chihuahua, French bulldog, Havanese, King Charles spaniel (the English toy spaniel), Maltese terrier, miniature dachshunds, miniature and toy poodles, Papillon, Pomeranian, Pugs, Shih Tzu, Staffordshire bull terrier, and the Yorkshire terrier. See SM in Other Breeds, below, for links to Internet articles about syringomyelia in some of these breeds.
Chiari-like malformation (CM or CLM) -- Occipital hypoplasia (OH) -- Caudal occipital malformation syndrome (COMS)
* Cavaliers have been determined to be brachycephalic. See 2011 report.
-- Chiari-like malformation (CM or CLM)
Chiari-like malformation (CM or CLM) is named after a similar condition in humans, discovered by Dr. Hans Chiari. Chiari-like malformation is defined* as "a condition characterized by a mismatch in size between the brain (too big) and the skull (too small). There is not enough room for the brain and the back part (cerebellum and medulla) is pushed out the foramen magnum." The foramen magnum is a hole in the back of the skull -- the occipital bone -- which leads to the spinal cord. The cavalier appears to have a brain more appropriate for a bigger dog, about the size as that of a Labrador retriever.
* The definition of this term underwent a revision in 2010. Previously to 2010, CM was defined as "decreased caudal fossa volume with caudal descent of the cerebellum, and often the brainstem, into or though the foramen magnum."
CM can be progressive, in the sense that over a period of several months, the length of the cerebellar herniation can increase significantly. However, the severity of CM in a dog does not predict the presence of syringomyelia in that dog. Therefore, other factors are believed to influence the development of a syrinx.
See Karen Kennedy's** Understanding Canine Chiari Malformation and Syrningomyelia for diagrams of the occipital bone and foramen magnum.
** Posted with the permission of Karen Kennedy, RTMR, MappSc, a magnetic resonance imaging specialist with The London Health Sciences Centre, London, Ontario, Canada. She prepared these diagrams on behalf of the Health & Education Committee of the CKCSC of Canada.
--- history of Chiari-like malformation research
There is not yet a consensus among veterinary investigators as to how to
measure the cavalier's occipital bone to determine what should be the shape
of the cerebellum within a "normal" CKCS's occipital bone.
Dr.
Clare Rusbridge, BVMS, MRCVS, PhD, DipECVN (right), of the Stone
Lion Veterinary Centre in London, England, a leading investigator into SM,
has described the three "classic features" of Chiari-like malformation as:
(1) loss of the normal round shape of the cerebellum, which can appear to be
indented by the occipital bone; (2) displacement of the cerebellum into and
through the foramen magnum, i.e. herniation; and (3) kinking of the medulla.
2009 and 2010 UK studies in which Dr. Rusbridge later participated
(discussed below) suggest that caudal fossa volume may also play a role in
CM.
In a 2006 study conducted by Dr. Natasha J. Olby and Dr. Sofia Cerda-Gonzalez, both board certified veterinary neurologists, and others at North Carolina State University's College of Veterinary Medicine's Department of Clinical Sciences and the IAMS Pet Imaging Center in Raleigh, NC., they have concluded that the incidence of caudal fossa and cervical spinal abnormalities is high in Cavaliers, and that the pathogenesis of syringomyelia is multi-factorial rather than due to a single malformation.
In a 2009 Scottish study led by Dr. Jacques Penderis, of 70 cavaliers and 80 dogs of other breeds, the researchers found that "all [of the] CKCSs had abnormalities in occipital bone shape. ... CKCSs had a shallower caudal cranial fossa and abnormalities of the occipital bone, compared with those of mesaticephalic dogs. These changes were more severe in CKCSs with syringomyelia."
However, in a January 2009 article, Drs. Sofia Cerda-Gonzalez, Natasha J. Olby, Susan McCullough, Anthony P. Pease, Richard Broadstone, and Jason A. Osborne failed to find the same association when comparing the caudal fossa of CKCS with and without syringomyelia using three-dimensional measurement methods.
Research journal articles published in 2009 and 2010 point to evidence that cavaliers' hind-skull volumes are not different from other small breeds, particularly those with short muzzles, and that the percentage of the volume of the caudal fossa -- the hind-skull cavity -- to the volume of the total cranial cavity, did not differ significantly between those CKCSs with and without SM.
However, these studies also found that the volume of hindbrain within the hind-skull was significantly greater for young -- 2-years and younger -- cavaliers with SM than older dogs -- 5 years and older -- without SM. They also found that increased hindbrain volume in CKCSs with SM, compared to that of the hind-skull, was directly correlated with the size of the dogs' syrinxes.
The first of these investigations was a 2009 German study of 40 cavaliers and 25 dogs of other brachycephalic breeds. The researchers found that: (1) "All CKCSs had cranial characteristics consistent with CLM"; and (2) "There were no significant differences between CKCSs and brachycephalic dogs with respect to the ... volumes of the CF [caudal fossa*] ...". They concluded: "Results of this study suggested that descent of the cerebellum into the foramen magnum and the presence of syringohydromyelia in CKCSs are not necessarily associated with a volume reduction in the CF of the skull."
* The caudal ( for "rear") cranial fossa is part of the cavity within the skull. It contains the brainstem and cerebellum, and towards its rear, it is enclosed by the occipital bone, which also frames the opening called the foramen magnum.
Similarly, in a 2009 UK study comparing the cerebral cranium volumes of the CKCS with those of other small breeds and the Labrador retriever, Hannah Cross and Drs. Rusbridge and Rodolfo Cappello found that cavaliers do not have a proportionately smaller caudal fossa compared to other small breeds, but that the CKCS's brain is comparatively large.
In that 2009 UK study, the researchers stated:
"When compared with Labradors, CKCS had proportionately the same volume of parenchyma [hindbrain] in their caudal fossa [skull], hence there is a mismatch of volumes with too much parenchyma in a too small caudal fossa causing overcrowding. ... Other small breeds of dogs had a proportionately smaller volume of parenchyma in their caudal fossa which can explain why, despite having a similar sized caudal fossa to CKCS, they do not experience overcrowding. It is hypothesised that through the miniaturisation process of other small dogs, both the cranium and brain are proportionately smaller but in CKCS only the cranium has reduced in volume, hence why there is a higher incidence of CM in CKCS than other small breeds.
"Cavalier King Charles spaniels also had a greater percentage of their cranial fossa filled with parenchyma (cranial fossa parenchyma percentage) compared with small breeds and Labradors which had a similar percentage. Overcrowding in CKCS might therefore occur due to a mismatch in volumes in both the caudal fossa and cranial fossa of the skull, suggesting the cranial fossa is also involved in the pathophysiology of CM."
They conclude:
"The results support mesoderm* insufficiency or craniosynostosis** as the pathogenesis of Chiari-like malformation (CM) in CKCS. It presents evidence for overcrowding of the caudal fossa due to a mismatch of brain parenchyma and fossa volumes as to why CKCS and not other small dogs are affected."
*The mesoderm is the middle of the three primary germ cell layers -- the others being ectoderm and endoderm -- in the early stage of an embryo. The mesoderm is responsible for developing various tissues and structures, such as bone, muscle, connective tissue, and the middle layer of the skin. Mesoderm insufficiency during embryology may cause insufficient scope for the mesoderm and ectoderm layers to develop.
**Craniosynostosis is the premature closure of the skull's growth plate.
This suggests both a possible genetic cause of the displacement of the cerebellum through the foramen magnum, as well as evidence that the cavalier's skull may not be too small, but that its hindbrain is too large, hence the "mismatch".
To the contrary, however, in a 2009 Scottish study led by Dr. Jacques Penderis, of 70 cavaliers and 80 dogs of other breeds, the researchers found that "all [of the] CKCSs had abnormalities in occipital bone shape. ... CKCSs had a shallower caudal cranial fossa and abnormalities of the occipital bone, compared with those of mesaticephalic dogs. These changes were more severe in CKCSs with syringomyelia."
In a 2010 UK study report
in the Journal of Small Animal Practice (JSAP),
Colin J. Driver
(right), Dr. Clare Rusbridge, et al.
reiterated findings that
the variations in the dimensions of the cavaliers' posterior
[caudal] cranial
fossa* may not be associated with syringomyelia, since cavaliers do not have
a proportionately smaller caudal cranial fossa compared to other small
breeds. See, also, an abstract of that study
presented before the European College of Veterinary Neurology (ECVN).
*The posterior (or caudal -- for "rear") cranial fossa is part of the cavity within the skull. It contains the brainstem and cerebellum.
The JSAP 2010 study researchers found that a cavalier with a higher volume of hindbrain within the skull is more likely to have SM, and the greater the volume of hindbrain, the larger the syrinx. They also found a direct relationship between between the dimensions of the brain ventricles ("ventriculomegaly" -- see below) and the size of the syrinx.
In addition, the 2010 JSAP research suggested that there may be a "failure of communication" between the paraxial mesoderm* and the cranial somites** with the closing neural tube*** in the embryo, resulting in loss of coordination between the growth of the skull and the hindbrain. When functioning properly, the growth of the mesoderm supports and helps to facilitate the closure process of the neural tube. They concluded that overgrowth of the cerebellum in the embryo may cause the mis-match, because cavaliers have proportionately more hindbrain volume than other small breed dogs. They stated: "Early growth plate closure may result in CM because despite the dynamic nature of osseous tissue, it would be unable to accommodate the developing brain."
*Paraxial mesoderm forms the supraoccipital bone.
**Cranial somitic mesoderm forms the exoccipital and basioccipital bones.
***The neural tube in the embryo develops the brain and spinal cord.
Then, later in 2010, the authors of the 2010 UK JSAP report presented an abstract before the 2010 congress of the British Small Animal Veterinary Association (BSAVA), in which they re-affirmed that, while SM occurs in cavaliers which have CM, it is the mis-match between the volumes of the hindbrain and the hind-skull which is believed to actually lead to SM, if not be the cause of SM. In that abstract, the authors go on to conclude that the more marked volume mis-matches they found between the hindbrain and the skull, the more severe the SM which affected the young dogs -- under 2 years of age -- in the study.
In a December 2010 UK study, led by Colin Driver, the researchers' results were consistent with the previous findings that ventriculomegaly and a small but significant increase in caudal fossa parenchyma are associated with syringomyelia. Further, this December 2010 study also found that the volume of the skulls of CKCS under 2 years of age and SM-affected were significantly smaller than the skull volumes of cavaliers over 5 years of age and SM-clear.
The UK studies in 2009 and 2010 suggest that a disproportionately large hind portion of the brain may be a necessary element of SM in the breed. These 2009 and 2010 research reports explain why CM has been re-defined as "a condition characterized by a mismatch in size between the brain (too big) and the skull (too small). There is not enough room for the brain and the back part (cerebellum and medulla) is pushed out the foramen magnum."
In a June 2011 study, which included Drs. Rusbridge, Driver, and McGonnell, they reported that twelve CM-affected cavaliers' foramen magnums and the length of cerebellar herniation "increased significantly" between MRI scans 9.5 months apart. they concluded:
"This work could suggest that overcrowding of the caudal cranial fossa in conjunction with the movements of cerebrospinal fluid and cerebellar tissue secondary to pulse pressures created during the cardiac cycle causes pressures on the occipital bone. This leads to a resorption of the bone and therefore an increase in caudal cranial fossa and foramen magnum size allowing cerebellar herniation length to increase."
--- most recent findings of Chiari-like malformation research
In an
April 2012 study by
Thomas A. Shaw, Imelda M. McGonnell, Colin
J. Driver, Clare Rusbridge, and Holger A. Volk, they
concluded that:
"the CKCS has a relatively larger cerebellum [in purple at right] than small breed dogs and Labradors and there is an association between increased cerebellar volume and SM in CKCS. In contrast to small breed dogs and Labradors, CKCS exhibit correlation between increased cerebellar volume and cerebellar crowding within the caudal CCF, suggesting that CCF growth in CKCS is not keeping pace with the growth of the cerebellum.
"These findings support the hypothesis that it is a multifactorial disease process governed by increased cerebellar volume and failure of the CCF to reach a commensurate size."
They also found:
(a) "CKCS under the age of 2 with SM have an increased cerebellar volume when compared to CKCS over the age of 5 without SM. This supports hypothesis that increased cerebellar volume in CKCS is associated with syringomyelia. Previous volumetric studies in CKCS have shown that there is an association between SM and CCF parenchyma volume, but this is the first time that cerebellar volume has been linked to SM. The cerebellum to brain volume ratio is consistent between normal dogs and has been shown to decrease with cerebellar degenerative disorders, but it has never been shown to be increased in size in a canine neurological disorder."
(b) "The degree of cerebellar crowding in the caudal CCF is correlated with increased volume of the cerebellum in CKCS, and this is not seen in small breed dogs or Labradors."
(c) "The degree of crowding may determine the degree of foramen magnum obstruction, and in turn the tendency for syrinxes to form. Cerebellar volume is potentially a key factor in determining the degree of obstruction and interference in normal CSF flow through the foramen magnum, which disposes dogs to the subsequent development of SM."
(d) "In CKCS an increase in relative cerebellar volume is correlated with an increase in cerebellar crowding in the caudal CCF. It should be noted that small breed dogs and Labradors do not show the same relationship. We infer from this result that during cranial development in Labradors and small breed dogs, a compensatory mechanism maintains the relationship between cerebellar volume and CCF dimensions, and this mechanism is defective in CKCS."
(e) "We also found in CKCS that cerebellar crowding in the caudal CCF is more sensitive to changes in relative cerebellar volume than cerebellar crowding in the rostral CCF, which is consistent with the theory that increased cerebellar volume results in the cerebellum shifting caudally and causes obliteration of dead space in the caudal CCF. This also causes herniation of the cerebellum through the foramen magnum (i.e. CM)."
(f) "In this study, we find that in CKCS, unlike small breed dogs or Labradors, there is a positive correlation between the volume of the cerebellum and degree of crowding in the caudal CCF, which suggests that CM may be due to CCF development not keeping pace with growth of the cerebellum. This supports the idea that CM/SM in CKCS may in fact be multifactorial and an abnormal development process affecting the CCF may be acting as a disease modifier."
(g) "Impaired CCF development may be caused by a failure of communication between one or more of these progenitors and the developing neural tube (specifically, rhombomere 1, which gives rise to the cerebellum). Alternatively, it could simply be explained by premature closure of growth plates between the bones of the CCF."
(h) "It has also been noted on post-mortem examination of CKCS and other small breed dogs that the supraoccipital bone overlying the cerebellar vermis is remarkably thin and sometimes eroded so that the foramen magnum is enlarged dorsally, which could indicate that there has been substantial bone resorbtion. Work is needed to elucidate the mechanisms of occipital growth in dogs to determine the extent to which an osteoresorbtive process can mitigate an enlarged cerebellum in CKCS and in other breeds."
However, in a June 2012 article, German researchers Martin J. Schmidt, Martin Kramer, and Nele Ondreka compared the volumes of occipital bones of cavaliers with and without syringomyelia and of French bulldogs. They did not find a reduced volume of the occipital bone of CKCSs, compared to the bulldogs. They concluded:
"These results do not support occipital hypoplasia as a cause for syringomyelia development, challenging the paraxial mesoderm insufficiency theory. This also suggests that the term Chiari-like malformation, a term derived from human studies, is not appropriate in the Cavalier King Charles spaniel."
The authors of this 2012 German article seemed mired in the pre-2010 definition of Chiari-like malformation. They state:
"... [T]he Chiari-like malformation in the Cavalier King Charles spaniel is characterized by indentation of the occipital (bone) with cerebellar herniation and is more correctly termed caudal occipital malformation syndrome."
They also appear to be unduly dismissive of the studies beginning in 2009 which found that the cavalier's cerebellum is relatively larger than that in other breeds. The authors of the 2012 German article did not include cerebellum size in their study, and their comment about the 2009-2012 reports simply is:
"Results of studies proposing a mismatch between cerebellar and caudal cranial fossa volume in this breed and in comparison to other breeds were controversial. In some studies, there was a mismatch between caudal fossa parenchyma and caudal fossa volume in dogs with syringomyelia and overcrowding was proposed as a cause of syringomyelia development. In most studies, however, no difference was found between caudal fossa volume in Cavalier King Charles spaniels with and without syringomyelia, although this was not universal." (Emphasis added.)
In a February 2013 report, UK researchers T. A. Shaw, I. M. McGonnell, C. J. Driver, C. Rusbridge, and H. A. Volk compared MRI scans of 45 CKCSs, 38 dogs of other small breeds, and 26 Labrador retrievers, and concluded:
"The data support the hypothesis that CM/SM in CKCS is a multifactorial disease process governed by the effects of increased hindbrain volume and impaired occipital bone development. The present authors recently reported that CM/SM is linked to increased cerebellar volume (Shaw and others 2012). In view of this, the aetiopathogenesis of CM/SM may equivocally be mediated by conditions independently affecting the developing occipital bones and cerebellum, or by dysregulation of a signalling mechanism coordinating the growth of the developing hindbrain and occipital skull."
--- other factors leading to SM
The severity of CM in a dog does not predict the presence of syringomyelia in that dog. Therefore, other factors are believed to influence the development of a syrinx. Ongoing research into genetic correlations between CM and SM seeks to determine whether different genes may control the expression of SM and CM. If so, it may be possible to select breeding stock which has been diagnosed to have CM but may not be expected to produce offspring with SM genes.
-- occipital hypoplasia (OH)
Occipital hypoplasia (OH) has been used to describe the displacement of the cerebellum into the area of the foramen magnum and a kinking of the medulla and an indentation of the cerebellum. "Hypoplasia" is a medical term defined as underdevelopment or incomplete development, and so, "occipital hypoplasia" in this instance means an underdeveloped or incompletely developed occipital bone, which is part of the back of the skull. However, at the November 2006 London conference, this term was rejected because there is no proof yet that the condition is related to a hypoplastic occipital bone. The actual disorder is believed to be caused either by an unusually small occipital bone or a confining membrane within the occipital bone, resulting in the cavity in the skull containing the cerebellum to be too small to fully contain it, leading to overcrowding of the caudal fossa and obstruction of the neural structures, including the incomplete closure or development of the neural tube through which flows the cerebrospinal fluid (CSF).
In a
January 2009 article,
Drs. Sofia Cerda-Gonzalez, Natasha J. Olby (left), 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."
However, in a June 2012 article, German researchers Martin J. Schmidt, Martin Kramer, and Nele Ondreka compared the volumes of occipital bones of cavaliers with and without syringomyelia and of French bulldogs. They did not find a reduced volume of the occipital bone of CKCSs, compared to the bulldogs. They concluded: "These results do not support occipital hypoplasia as a cause for syringomyelia development, challenging the paraxial mesoderm insufficiency theory."
Occipital hypoplasia is to be distinguished from occipital dysplasia, which is an incomplete ossification of the supraoccipital bone, causing a widening of the foramen magnum. The more brachycephalic is the shape of the dog's skull, the more likely there will be occipital dysplasia. The cavalier is a brachycephalic breed, and therefore a combination of both occipital hypoplasia and occipital dysplasia can occur in the CKCS.
In a 2008 German study, the researchers recommend that cavaliers be screened for both occipital hypoplasia and occipital dysplasia.
-- caudal occipital malformation syndrome (COMS)
Caudal occipital malformation syndrome (COMS) had been used, particularly by some specialists in the United States, to describe the disorder. However, at the November 2006 London conference, the term COMS also was rejected because there is no proof yet that the condition is related to a malformed occipital bone. Nevertheless, some diehard neurologists in the northeast USA persist in using this term when referring to Chiari-like malformation in cavaliers. Similarly, the authors of a 2012 German article insist that:
"... [T]he Chiari-like malformation in the Cavalier King Charles spaniel is characterized by indentation of the occipital (bone) with cerebellar herniation and is more correctly termed caudal occipital malformation syndrome."
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.
* Posted with the permission of Karen Kennedy, RTMR, MappSc, a magnetic resonance imaging specialist with The London Health Sciences Centre, London, Ontario, Canada. She prepared these diagrams on behalf of the Health & Education Committee of the CKCSC of Canada.
-- pain due to CM
Dogs with CM but not syringomyelia (SM) can experience discomfort, including pain. This is attributed to a direct compression of the medulla oblongata, which is involved in the modulation of pain. See our section on expressions of pain as a symptom of SM, below, for information about CM and SM pain research.
In an October 2012 study by UK researchers of 48 cavaliers, nine of which had only CM and the rest also had SM, neuropathic pain progressed in 75% of the dogs over a mean average period of 39 months. The researchers noted that it is not fully understood how CM/SM causes neuropathic pain, and they did not make any such finding. However, their report confirms that neuropathic pain does exist, and it progresses, in cavaliers with only CM.
What SM is
Syringomyelia (SM) is defined as "a condition that results in the development of fluid-containing cavities within the parenchyma of the spinal cord. as a consequence of abnormal cerebrospinal fluid movement." (November 2006 International Conference on Syringomyelia).
Cerebrospinal fluid normally flows back and forth between the brain and spinal cord with each heart beat. As the heart pumps blood to the brain, the CSF flows from the brain through the hole called the foramen magnum to the spinal cord, to accommodate the increased volume of incoming blood.
Syringomyelia is believed to result when the cerebrospinal fluid is prevented from circulating normally between the brain and spinal cord, due to a narrowing or blockage of the CSF flow at the foramen magnum, thereby forcing the CSF at a higher than normal pressure into the spinal cord. The pressure difference causes the spinal cord to distend or pull apart, creating a cavity called a syrinx, and squeezing fluid from blood vessels and other tissues into the cavity.
Syringomyelia is an extremely serious, progressively worsening spinal disease which is rare in most breeds but is becoming very widespread in cavalier King Charles spaniels of all bloodlines. In May 2005, Dr. Rusbridge and Susan P. (Penny) Knowler, BSc (Hons), who have been studying the disease in several hundreds of cavaliers, reported that a conservative estimate is that at least 50% of cavalier King Charles spaniels have a degree of Chiari-like malformation, although not all are so severely affected as to have syringomyelia. In February 2010, Dr. Georgina Child, board certified veterinary neurologist in Australia, reported that of 60 asymptomatic cavaliers scanned as potential breeding stock, 50% had SM syrinxes. In a September 2010 report of 804 cavaliers, Mrs. Knowler and others estimated that "the lifetime risk of developing syringomyelia in the study population was estimated to be 55%."
In a 2011 study of 49 cavaliers diagnosed with SM, Dr. Rusbridge and others found that "total syrinx size was positively correlated with age" of the dogs. In a June 2011 study of 555 cavaliers without any symptoms of syringomyelia, 25% of the one year old dogs had SM and 70% of the dogs aged 6 years and older had SM.
-- role of the ventricle system (vetricular dilatation - ventriculomegaly)
The brain's ventricle system consists of
four cavities which are connected with the spinal cord's central canal. The
four ventricles are known as the two lateral ventricles, the third
ventricle, and the fourth ventricle. The ventricles are the source of CSF
and are the brain's respository of CSF.
Some neurologists are including in their examination reports an analysis of whether the ventricles are dilated, and if so, a measurement of the amount of their dilatation. The medical term for dilated lateral ventricles is ventriculomegaly. In a December 2010 UK study, also led by Colin Driver, the researchers' results were consistent with the previous findings that ventriculomegaly and a small but significant increase in caudal fossa parenchyma are associated with syringomyelia.
-- other causes of SM
There are other forms of syringomyelia in canines. Spinal dysraphism or spinal dysplasia is a genetic disorder in which puppies normally under the age of three months display a bunny hopping gait and wide-based stance and scoliosis, due to the spinal cord not developing completely in the womb. Dalmatians, English setters, golden retrievers, rottweilers, visla, and Weimaraners have been identified with this disorder. Also, SM may be caused by tumors, cysts, or trauma. Neither of those are discussed here.
Symptoms
Symptoms may vary widely among different dogs, but the earliest sign often is that the dog feels a sensitivity in its neck area, causing in some an uncontrollable urge to scratch at its neck and shoulders excessively, particularly when walking or during other forms of exercise, and usually without making skin contact (phantom scratching). This is believed to be 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 a pins-and-needle-like tingling or a burning-type pain, and other strange sensations (called dysaesthesia), which prompt the dog to scratch. Some dogs perform facial or head rubbing or spontaneous vocalizations. Click here or the YouTube logo (above) to see videos of cavaliers with SM symptoms.
Many symptoms of SM, such as scratching, are so ordinary (when not
excessive or compulsive) that they could be attributed to any of several common
causes, including flea bites or allergies. Others, such as limping or lack of
muscle coordination also could be confused with injuries or other disorders. Scoliosis (abnormal curving of the spine) is another physically apparent
symptom. See photo of a 9-month old cavalier at left with scoliosis.*
* Photo is from Dr. Clare Rusbridge.
SM and CM very seldom can be detected in young puppies, as symptoms usually are not evident before the age of six months or even many years later. There is no way to know in advance of the symptoms whether a dog is normal or is a syringomyelia carrier which does not develop the disease but can pass it on to its offspring.
The condition causes damage to the spinal cord and usually results in symptoms of hypersensitivity, intense pain, and leg dysfunction. The primary symptoms may vary widely, and in some cases, a cavalier may even have SM without displaying any outward symptoms at all. Some cavaliers diagnosed with SM lack any clinical signs. It also is possible that a dog with Chiari-like malformation (CM) does not have syringomyelia (the syrinx in the spinal cord), but still may have symptoms of SM due to the CM obstructing the flow of cerebrospinal fluid (CSF). This also is attributed to a direct compression of the medulla oblongata, which is involved in the modulation of pain.
An excellent review of the various symptoms displayed by dogs affected with syringomyelia may be found on the SM.CavalierTalk.com website, prepared by Karlin Lillington of Dublin, Ireland. Her website includes videos of SM-affected dogs. Other videos are available under Related Links below.
-- expressions of pain
As the disorder progresses, there usually follows increasingly severe
pain around the dog's head, neck, and shoulders, causing it yelp or scream.*
It is believed to be a neuropathic pain, probably due to disordered neural
processing in the damaged dorsal horn.
Nevertheless, as recently as October 2012, researchers still state that, "It is not yet fully understood how CM/SM causes NeP [neuropathic pain]."
Similar forms of neuropathic pain in humans suffering from Chiari type I malformation (the human counterpart to CM) and SM include: (a) a burning type pain, pins-and-needles and other odd sensations (called dysaesthesia); (b) pain from a stimulus which is not normally painful, such as light touch or motion (called allodynia); (c) increased pain from stimuli which are normally painful (called hyperpathia,); and (d) a constant, burning type pain (called causalgia). In humans, neuropathic pain also is associated with anxiety, depression, and reduced quality of life.
As the disease destroys portions of the cavalier's spinal cord, the dog may experience so much pain that it may contort its neck and may even sleep and eat only with its head held high. Ultimately, the dog may develop scoliosis, as a result. There may also be progressive weakness in the legs, so that walking becomes increasingly difficult. Some dogs deteriorate to the point of paralysis.
* Photo at right above is of a cavalier suffering severe head pain due to SM. Photo below left is of a cavalier writhing in pain from SM. Photo above is from Dr. Clare Rusbridge. Photo below is from Pedigree Dogs Exposed.
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. Similarly, in an August 2012 study, the researchers found evidence that:
"... the disruption of the dorsal horn structure is a significant event in the production of clinical signs in CKCS. The spinal cord dorsal horn in symptomatic CKCS is significantly more asymmetric than that of control animals, whereas the asymptomatic CKCS have changes that are midway between control and symptomatic CKCS. This suggests the possibility that progression from mild to severe asymmetry in CKCS is associated with development of clinical signs; however such a conclusion cannot be definitively supported by this study because of the cross sectional nature of the data collected."
Syringomyelia can be very deceptive because some symptoms (which may
include paw licking, head shaking, head rubbing, circular walking, fly
biting, and reluctance to defecate) are common behaviors for many unaffected
dogs. One distinction is that dogs suffering from SM engage in these
patterns excessively and seemingly compulsively. So, other causes of the
dog's symptoms need to be considered and should be ruled out before
concluding that SM is the cause. For example, if a syrinx develops in a
lower area of the spine, such as the lumbar region, the dog may scoot
excessively, even to the extent of rubbing the anal area raw. However,
scooting is a common symptom of other disorders, or even of no particular
disorder at all.
In a 2009 study of 64 cavaliers affected with CM/SM, Drs. Sofia Cerda-Gonzalez, Natasha J. Olby and others classified clinical signs of pain from grade 0 to grade 5, by which the dogs displayed symptoms of neck scratching, head scratching, neck pain upon neurolgoical examination, as well as ataxia and paresis detected upon examination. See table below:
In a 2010 Canadian study, researchers found a significant linear correlation between the severity of neurologic dysfunction and size of the syrinx, with a larger syrinx being associated with more severe neurologic signs.
In an April 2012 study, Geoffrey Skerritt and Dr. Luca Motta observed that the level of neurological pain a dog experiences can only be based upon subjective evaluations of the dog's behaviors, which includes the dog's owner's subjective observations.
In order to evaluate changes in the level of a dog's discomfort as objectively as possible, to determine whether their surgical procedure on the dog was successful (see "syringosubarachnoid shunt" below) these neurosurgeons devised a Pain Score Scheme (see table below) for the dog's owners to measure pain which the dog experiences from CM and SM, particularly following surgery. Their pain score scheme was created on the basis of different neurological grade classifications previously suggested by other researchers, including the Cerda-Gonzalez / Olby 2009 study above. Mr. Skerritt and Dr. Motta evaluated their patients’ histories and found some specific information that could be used to create an objective pain score (i.e., frequency of scratching episodes and site of scratching, screaming episodes). However, because of the inherent subjectivity of relying upon reports from the dog's owners, they concluded that the design of a more robust scoring system together with prospective studies was warranted.
In a 2012 study, UK researchers (Lynda Rutherford, Annette Wessmann, Clare Rusbridge, Imelda M. McGonnell, Siobhan Abeyesinghe, Charlotte Burn, and Holger A. Volk) of cavaliers with neuropathic pain report on the results of far more extensive questionnaires (using a 5-point scale), completed by the owners of 122 CM/SM-affected CKCSs. They found that owners who noticed evidence of neuropathic pain in their dogs also found the dogs to have increased fear-related behaviors (such as acting more fearfully when approached by strangers, or when in unfamiliar situations, or when sudden loud noises occurred, such as thunderstorms). These dogs also were more clingy to their owners and appeared to be more fearful when left alone. They also showed decreased willingness to exercise, and problems in settling, including sleep disturbances. Not surprisingly, the study also showed that owners found that their affected dogs had reduced quality of life.
In an effort to pinpoint the locus of the pain caused by SM, in an August 2012 study, researchers Hilary Zhaoxu Hu, Clare Rusbridge, Fernando Constantino-Casas, and Nick Jeffery compared the expression of two pain-related neuropeptides* in the spinal cord dorsal horn of normal dogs with the peptides' expression in cavaliers with and without clinical signs of syringomyelia. They discovered that there was a decrease in expression of both peptides in CKCSs with symptomatic syringomyelia.
* Peptides are molecules formed by joining from two to about fifty amino acids. The two neuropeptides in this study were substance P and calcitonin.
In
an
April 2013
study of 26 cavaliers (11 dogs without clinical signs of pain; 6 dogs
with pain and symmetrical syrinxes; 9 dogs with pain and asymmetrical
syrinxes), German researchers
M.J. Schmidt, J. Roth, N. Ondreka, M. Kramer,
and C. Rummel
found "an association" between pain and SM
asymmetry, and they found "a strong association" between pain and dorsal
horn involvement of SM. CKCSs with clinical signs of pain showed either
asymmetrical
syrinxes or involvement of the dorsal horn gray matter. They also found that
cavaliers with clinical signs of pain showed a presence of interleukin-6 (a
key component of the nervous system’s response to injury) and substance P (a
neurokinin that regulates the immune functions of spinal glial cells) in
their cerebrospinal fluid (CSF). The researchers conclude that the release
of interleukin-6 and substance P is a factor in the development of
persistent pain in cavaliers with SM. They suggest that this information
could offer new diagnostic and treatment options for CKCSs with SM. (In
the study's photo above, the top three syrinxes are asymmetrical; the bottom
three are symmetrical.)
-- other disorders with similar symptoms
Another disorder common to cavaliers and with symptoms similar to SM is Primary Secretory Otitis Media (PSOM), which is a highly viscous mucus plug which fills the middle ear and causes the tympanic membrane to bulge. Because the pain and other sensations in the head and neck areas, resulting from PSOM, are so similar to symptoms due to SM, the possibility that the cavalier has PSOM and not SM should be determined before diagnosing SM.
In a brief July 2009 article, UK researchers Dr. Richard J Piercy and Gemma Walmsley disclosed that they had identified a genetic form of muscular dystrophy in the cavalier, with symptoms (weakness and exercise intolerance) similar to some of those of SM. However, these other symptoms of this muscular dystrophy may clearly distinguish it from SM: muscle atrophy, difficulty swallowing, and an enlarged tongue. Also, the researchers have found that only males are affected by this form of muscular dystrophy, and the females are only carriers of the mutation.
Also, see
flycatcher's syndrome for a description of another disorder prevalent in
CKCSs and which has identical symptoms to the fly biting of some
SM/CM-affected dogs.
Dr. Curtis Dewey has reported that in the course of his examination of MRIs of cavaliers with Chiari-like malformation, he also has discovered cerebellar infarcts (strokes). He has written that CKCSs appear to be pre-disposed to infarcts due to the presence of CM and that the existence of both CM and infarcts "is common in the CKCS." See Cerebellar Infarcts for details.
Dr. Rusbridge has a website, veterinary-neurologist.co.uk, which discusses SM extensively, as well as other neurological disorders which she has researched. Her doctoral thesis, a 200+ page book (right), Chiari-like Malformation and Syringomyelia in the Cavalier King Charles Spaniel, also is available online, for free.
Diagnosis
-- magnetic resonance imaging (MRI)
The only accurate way of diagnosing the disease is through the use of magnetic resonance imaging (MRI) scanning. Clinic charges for MRI examinations of canines have been known to vary from $400.00 to over $2,000.00. Accurate MRI results require that usually the dog be anesthetized. In view of the high cost of MRI scans, the examining veterinary specialist usually will attempt to rule out other causes of the symptoms first. Veterinarians who perform MRIs of should consider following this MRI Screening Protocol devised by Dr. Rusbridge.
The MRI allows the veterinary neurologist or neurosurgeon to study the
skull and spine for the presence of any abnormality which might
obstruct the flow of the cerebrospinal fluid. When examined by MRI,
the syringomyelia appears as a tubular cavity of fluid, called a syrinx,
within the spinal cord. In severe cases, the syrinx is so wide that only a
thin rim of the spinal cord is visible. An MRI scan of a dog without
any syrinxes at all still may show that the dog has Chiari-like
malformation.
The MRI scan of a cavalier at the right shows the occipital malformation, with the cerebellum being squeezed out of the occipital bone and into the area of the foramen magnum (red-outlined area). It also shows pockets of white cerebrospinal fluid in the spinal cord (yellow-outlined area). See Karen Kennedy's Basic Canine NeuroAnatomy and MRI Imaging Planes, for further information about MRI scans.
In a study conducted by Dr. Rusbridge and Ms. Knowler, in a sample of seventy "unaffected" cavaliers from Europe and North America, which were MRI-scanned only for breeding purposes, 70% of them had syringomyelia, 17% were "at risk", meaning were young dogs with Chiari-like malformation but no syringomyelia yet, and only 13% were "clear" of both the malformation and SM. In February 2010, Dr. Georgina Child, board certified veterinary neurologist in Australia, reported that of 60 asymptomatic cavaliers scanned as potential breeding stock, 50% had SM syrinxes.
In MRI studies of 49 cavaliers, reported in 2011 in the Veterinary Journal, Dr. Rusbridge and others found that "Syrinx formation was present in the C1–C4 region and in other parts of the spinal cord. The maximal dorsoventral syrinx size can occur in any region of the spinal cord." Seventy-six per cent of CKCS with a a cranial cervical syrinx also had a syrinx in more caudal spinal cord regions. Therefore, so-called "mini-MRI-scans" of only the cervical region, such as those scans for breeding protocol purposes, may not necessarily locate all syrinx which an SM-affected cavalier may have.
Dr. Curtis Dewey has reported that in the course of his examination of MRIs of cavaliers with Chiari-like malformation, he also has discovered cerebellar infarcts (strokes). He has written that CKCSs appear to be pre-disposed to infarcts due to the presence of CM and that the existence of both CM and infarcts "is common in the CKCS." See Cerebellar Infarcts for details.
-- computed tomography (CT)
Computed tomography (CT) is an imaging method using digital geometry
processing to generate a three-dimensional image of the inside of an object
from a large series of two-dimensional x-ray images taken around a single
axis of rotation. Researchers have been studying the value of CT scans to
detect Chiari-like malformations and syrinxes in cavaliers and comparing the
results with MRIs and other resources. In a very preliminary
2008 French study, researchers CT scanned sixteen CKCS to measure the
size of their caudal fossas and to determine standard computed tomography
dimensions of the caudal fossa.
Dr. Dominic J. Marino of Long Island Veterinary Specialists (LIVS) reported in October 2007 that evaluation of the entire skull shape and size utilizing Spiral CT technology with 3D reconstruction is currently underway to identify additional mechanisms of syrinx formation. He wrote that CT scanning may enable surgeons to focus on correcting the flow of CSF as the malformation affects its normal passage around the brain and spinal cord and leads to the syrinx formation known as syringomyelia.
-- thermography (medical infrared imaging -- MII)
Medical infrared imaging (MII), also called thermography, is a non-invasive imaging technique which records thermal
patterns. It provides information about the function of the sympathetic
nervous system. Thermal imaging has drawn the interest of veterinary
researchers as a potential screening test for CM in dogs due to its ability
to image dogs without sedation. In a preliminary 2007 study at Long Island
Veterinary Specialists (LIVS),
Dr. Dominic J. Marino's team
found that cavaliers with CM had “cooler” thermographic patterns when
compared with a dog with a normal caudal fossa. Dr. Marino reported in
October 2007 that, "based on these very preliminary findings, thermography
may be a viable imaging modality to use as a screening tool to detect CLM in
dogs."
In a June 2011 study of 105 cavalier King Charles spaniels, Drs. Marino and Catherine Loughin found that MII was up to 97.3% accurate in identifying dogs with CLM. They concluded, "Based on these preliminary findings, MII may be a viable screening tool to detect CLM in dogs."
Beginning in October 2012, a UK clinic, Veterinary Thermal Imaging Limited, has been studying thermal imaging to detect of dogs to detect Chiari-like malformation and syringomyelia. The procedure used to explore the use of thermal imaging for the screening of CLM is non-invasive. Thermal images are taken of the dog's head and neck. The images can be taken without the need for sedation, and in the dog's home. The thermographer then examines these images, along with MRI results, to see if a correlation can be seen between skull and neck structures in the affected animals. Veterinary Thermal Imaging Limited is located on Hale House Lane, Churt, Surrey, GU10 2JG. For more information, contact Stephanie Godfrey at Stephanie.godfrey@vtiuk.com, telephone 0844 544 3314, website www.veterinary-thermal-imaging.com
-- ultrasound
In 2005, Drs.
Dominik Faissler and
John (Jay)
McDonnell, board certified veterinary neurologists at the
Cummings School of Veterinary Medicine at Tufts University in Massachusetts,
researched the use of ultrasonography to diagnose syringohydromyelia in
dogs. In a 2005 interim report, they stated, "This preliminary study
indicates that cervical spinal cord ultrasound can be useful as a diagnostic
aid for CM. It cannot rule out a diagnosis of CM, however no false positives
were found. To investigate the sensitivity and specificity of this imaging
modality blinded U/S examination of large numbers of dogs after MRI
evaluation is planned."
In the same 2008 French study reported under computed tomography above, one dog's syrinx was identified by ultrasound. The researchers found that ultrasonography probably has too low a sensitivity for reliable diagnosis of Chiari-like malformation/syringomyelia.
In an August 2008 report by German researchers using ultrasound as a comparative imaging technique to MRIs, they compared 10 normal brachycephalic dogs with 25 cavaliers known to have Chiari-like malformation. They found that "Cerebellar displacement into the foramen magnum was clearly identified sonographically; however, syringohydromyelia was not discernable due to bone overlay."
-- brainstem auditory evoked response (BAER)
A supplemental diagnostic screening tool used by at least two veterinary
neurologists, Dr. Curtis W. Dewey and
Dr.
Georgina Barone, and by
Dr. Dominic J. Marino is
the BAER (for Brainstem Auditory Evoked Response) test. The BAER test
measures the timing of electrical waves from the brainstem in response to
clicks in the ear. Dr. Dewey reported that, assuming the dog is not deaf,
the detected brain waves can be used to assess the integrity of the brain
stem, since CM involves some degree of brain stem compression.
As of October 2007, Dr. Marino reported that "38 Cavalier King Charles Spaniels had been evaluated thus far. One dog had a normal MRI, BAER, and thermographic evaluation. Twenty-three dogs without clinical signs had abnormal MRI findings with 16 of the 23 dogs (69.6%) also having abnormalities with BAER testing. Fourteen dogs with clinical signs had abnormal MRI findings and 13 of the 14 dogs (92.8%) also had abnormal BAER tests. BAER testing may play a more useful role in screening 'clinical' dogs rather than dogs without clinical signs.
In a 2010 report, a group of Canadian neurologists tested fifty cavaliers to evaluate the validity of BAER as well as transcranial magnetic motor evoked potentials (TMMEP), somatosensory evoked potentials (SSEP), and spinal evoked potentials (SEP), compared to MRIs. The researchers found: "TMMEP, SSEP, SEP and BAER do not appear to be valuable tests in detecting functional abnormalities of the motor and sensory pathways throughout the central nervous system of CKCS dogs with and without neurological signs secondary to SM diagnosed by MRI."
The following MRI photographs, and their descriptive text, are courtesy of Dr. Clare Rusbridge and Ms. Penny Knowler of Stone Lion Veterinary Centre:
Left: This image shows mild Chiari-like malformation – the cerebellum is very slightly indented, the kinking of the medulla is normal for a toy breed and there is displacement of the cerebellum into and just out of the foramen magnum. The ventricular system is slightly dilated.
Right: Although the cerebellum is not coming through the foramen magnum,
this dog has a greater degree of Chiari-like malformation than the first
dog. The cerebellum is indented, and the medulla is kinked. The central
canal is dilated above the first disc space – this is the first sign of
syringomyelia developing. There is also mild ventricular dilatation.
Left: This dog has descent of the cerebellum towards the foramen magnum and the
cerebellum is indented. The medulla is normal for a toy breed; there is mild
ventricular dilatation and a small syrinx/central canal dilatation in the
upper cervical spinal cord.
For more MRI views of cavaliers with syringomyelia or the Chiari-like malformation, see Karen Kennedy's* Understanding Canine Chiari Malformation and Syrningomyelia and Related Links below.
*Karen Kennedy, RTMR, MappSc, is a magnetic resonance imaging specialist with The London Health Sciences Centre, London, Ontario, Canada.
Reduced Rate MRI Clinics
in United States and Canada
The names and locations of veterinary neurologists who are board certified by the American College of Veterinary Internal Medicine (ACVIM) are on our Neurologists webpage. Some MRI clinics which are offering reduced rates for partial scans of cavaliers are listed below. Be aware that prices for MRI scans at these clinics are subject to change and may not include other services which are necessary for a complete analysis of the dog's condition. Veterinarians who perform MRIs are advised to follow the MRI Screening Protocol.
4LOS ANGELES, CA: Through January 2012, Dr. Sheila Carrera-Justiz, board certified veterinary neurologist, offers mini-scans for $750.00, which include the consultation, anesthesia, a copy of the MRI on CD and interpretation. The scan is from the inter-thalamic adhesion to C5 or lower. It also covers axials of the tympanic bullae to evaluate for PSOM. Blood work no older than one month is required and can be performed at the clinic. Contact Dr. Carrera-Justiz at VCA-West Los Angeles, at 1818 S. Sepulveda Blvd., Los Angeles, CA, 90025, Tel: 310-473-2951, Email: sheila.carrera-justiz@vcahospitals.com, website: www.vcawla.com
4LOS ANGELES, CA: Beginning in February 2012, Dr. Veronique Sammut, board certified veterinary neurologist, offers mini-scans for $750.00, which include the anesthesia, a copy of the MRI on CD and interpretation. The scan is from the inter-thalamic adhesion to C5 or lower. It also covers axials of the tympanic bullae to evaluate for PSOM ("glue ear"). Recent blood work (no older than one month) is required or can be performed at the hospital. Contact Dr. Sammut at VCA-West Los Angeles, at 1818 S. Sepulveda Blvd., Los Angeles, CA, 90025, Tel: 310-473-2951, Email: veronique.sammut@vcahospitals.com, website: www.vcawla.com
4REDWOOD CITY, CA: AnimalScan at 410 Brewster Avenue, Redwood City, CA 94063, telephone 650-480-2001, email info@animalscan.org See Easton, PA entry for details.
4GAINESVILLE, FL: Dr. Thomas A. Schubert, board certified veterinary neurologist and Chief of Neurology Service at the University of Florida's College of Veterinary Medicine, offers cavaliers an MRI Package for $650 to $750 per dog. This includes a full physical and neurological exam, general anesthesia and recovery, the MRI, consultation about the findings from the MRI, and a copy of the MRI to take home. Owners that would like to bring more than 3 dogs may be eligible for a discount on the exam fee. However, this must be discussed before you come for your appointment or you will not be given a discount. If your CKCS, has a history consistent with possible PSOM and the MRI confirms this diagnosis, then treatment can be performed during anesthesia for this MRI with the school's Dermatology Service for the additional cost of $350 to $500. This option must be discussed and arranged prior to appointment day. The conditions for this low fee are: (a) the owner brings a current blood test report (no more than two weeks old); and (b) there are no complicating health issues, such as heart problems. Contact Dr. Schubert's technician, Amy Reynolds, email Reynoldsa@ufl.edu
4NAPLES, FL: Dr. Michelle Carnes, board certified veterinary neurologist at Animal Specialty Hospital of Florida, offers an MRI package for asymptomatic (non-clinical) patients at $900.00 (for three or more dogs), $1,000.00 (for two dogs), and $1,100.00 for one dog. The MRI scan is a mini-scan from interthalamic adhesion to C5. The price includes a neurologic exam/physical prior to the scan and a consultation following the scan for review of study, anesthesia, a written interpretation of the scan, and a copy of the MRI on a CD. Bloodwork is required and is not included in the price. Bloodwork should be no older than two weeks. A report from a board certified veterinary radiologist can be obtained for an additional fee. For more information, contact Eric Carnes, telephone 239-263-0480, email ecarnes@ashfl.com. Animal Specialty Hospital of Florida is located at 10130 Market Street, Suite 1, Naples, Florida 34112, telephone: 239-263-0480, fax: 239-263-0488, website: www.ashfl.com
4FORT WAYNE, IN: Advanced Animal Imaging offers Cavalier breeders a $495.00 mini-scan MRI per dog, which includes a consultation, reading of the scan, and anesthesia. Pre-screening bloodwork is required prior to anesthesia and is available for $75.00 at the Indian Creek Veterinary Hospital in the same building. The clinic follows Dr. Rusbridge's SM MRI screening protocol. Contact the clinic at telephone 260-434-1555 to make appointments. Advanced Animal Imaging is located at 5902 Homestead Road, Fort Wayne, IN 46814, and its website is www.advancedanimalimaging.com
4AMES, IA: The Lloyd Veterinary Medical Center at the University of Iowa offers a mini-scan MRI package at approximately $800.00, consisting of an examination, MRI scan, and anesthesia. To schedule an appointment, call the neurology service at 515-294-4900. It is located at 1600 S. 16th Street, Ames IA 50011, and its website is vetmed.iastate.edu/vmc
4OVERLAND PARK, KS: Dr. Brian C. Cellio, board certified veterinary neurologist at Veterinary Specialty and Emergency Center in Overland Park, Kansas (near Kansas City) offers Cavalier breeders a $900.00 mini-scan MRI per dog for a minimum of five dogs up to ten dogs per day. Contact Dr. Cellio's technician, Mandi, telephone 913-642-9563 or 800-413-6851 to make appointments. The clinic is located at 11950 West 110th Street, Suite B, Overland Park, KS 66210, and its website is www.vseckc.com
4COMMERCE, MI: Drs. Michael Wolf, Jared B. Galle, and Andrew Isaacs, board certified veterinary neurologists at Animal Neurology & MRI Center in Commerce, Michigan, offer Cavalier breeders reduced rates as low as $975.00 for an MRI scan. Rate includes a neurological examination, anesthesia, MRI scan and consultation/review of the MRI study with the neurologists, for a minimum of three dogs. Review and MRI imaging report from their board certified radiologist can be requested for an additional fee. Contact Dr. Wolf at the Animal Neurology & MRI Center, 1120 Welch Road., Commerce, MI 48390, Tel: 248-960-7200, email DrWolf@animalneurology.com, website www.animalneurology.com
4COLUMBIA, MO: University of Missouri's College of Veterinary Medicine (Drs. Joan R. Coats, Dennis P. O'Brien, and Fred A. Wininger) offers CM/SM scans for $500.00, which includes "iso" anaesthesia. Blood work is additional and may be obtained ahead of time at your veterinarian's office. Contact Stephanie Gilliam, Neurology/Neurosurgery Technician, University of Missouri Veterinary Medical Teaching Hospital, 900 E. Campus Drive, Columbia, MO 65211, telephone 573-882-7821.
4ITHACA, NY: Cornell University's College of Veterinary Medicine's Department of Clinical Sciences, in Ithaca New York, is offering low cost MRIs (as low as $650.00 each). Contact Dr. Curtis W. Dewey, board certified veterinary neurologist and board certified veterinary surgeon, telephone 607‑253-4445, email cwd27@cornell.edu See more about Dr. Dewey under Current Research below.
4PLAINVIEW, NY: Long Island Veterinary Specialists (LIVS) in Plainview, New York offers low cost MRIs and other procedures, including BAER, thermography evaluation, and a neurology consultation. LIVS has plans to add spiral CT to the evaluation soon. The program is open to all dogs, but the lowest rates -- as low as $500.00 -- are for dogs in groups of three or more. Contact Dr. Dominic J. Marino, board certified veterinary surgeon and chief of staff, telephone 516-501-1700 (ask for Alexis or Lexi), email Bongorno@aol.com, webpage www.livs.org. Dr. Marino advises that LIVS averages 20 MRIs per week and has operated on an average of one dog diagnosed with COMS per week for the past several years. See more about Dr. Marino under Current Research below.
4RALEIGH, NC: AnimalScan, at North Carolina State University's College of Veterinary Medicine's Department of Clinical Sciences, 4700 Hillsborough Street, Building 3, Raleigh, NC 27606, telephone 919-838-5209, email raleigh@animalscan.org See Easton, PA entry below for details.
4AKRON, OH: Pets Dx Veterinary Imaging, Inc. in Akron, Ohio and Pittsburgh, Pennsylvania, offers a partial MRI, at reduced group rates for Cavaliers, focusing on the head and neck, and includes a compact disc with an imaging program. Their MRIs may be reviewed, for an additional fee, by Dr. Patrick R. Gavin, Diplomate ACVR, Professor of Radiology, Washington State University College of Veterinary Medicine, in consultation with the dog's veterinarian. Pets Dx Veterinary Imaging, Inc. is located at 1321 Centerview Circle, Akron, Ohio 44321, telephone 330-576-6275, and at 807 Camp Horne Road, Pittsburgh, PA 15237, telephone 412-486-4800 and 412-348-2577. Its website is www.petsdx.com
4MISSISSAUGA, ON: Matheson Boulevard Veterinary Services in Mississauga, Ontario offers reduced cost MRIs for Cavalier breeders, through the efforts of the CKCS Club of Canada. See details and current prices on the club's website CavalierCanada.com Participants will receive a full neurological exam by a Veterinarian. They will also receive a full MRI that meets all current scanning protocols, a CD copy of their MRI screening, and a grading certificate issued by Dr. Clare Rusbridge. See the clinic's website mbvs.ca for information about required border-crossing documentation.
4EASTON, PA: AnimalScan offers mini-MRI scans for $500.00, following the proposed new SM MRI-scanning protocol. This offer is to Cavalier breeders for screening purposes. AnimalScan has a board certified radiologist, Dr. Alexia McKnight, but does not have a neurologist on staff and does not provide medical care. If a dog is symptomatic, the fee for a full diagnostic scan to determine the extent of disease would be from $1425 to $1950. AnimalScan is located at 2026 Lehigh Street, Easton, PA 18042. Contact: Medical Director Dr. Meg Alonso, telephone 877-838-6747, email DrAlonso@AnimalScan.org, website www.AnimalScan.org
4PITTSBURGH, PA: Pets Dx Veterinary Imaging, Inc., 807 Camp Horne Road, Pittsburgh, PA 15237, telephone 412-486-4800 and 412-348-2577. See Akron, Ohio entry above for details.
4MT PLEASANT, SC: Dr. Peter J. Brofman, (ACVIM Neurology & Internal Medicine) and Veterinary Specialty Care offer a reduced rate for MRIs for breeding screening protocols only. The fee of $1000 includes the MRI and anesthesia but pre-anesthetic blood work is not included. The MRI unit is a 1.5T magnet and is available for screenings Monday through Friday. Veterinary Specialty Care is located at 930 Pine Hollow Rd, Mt. Pleasant, SC 29464. You may contact Dr. Brofman at 843-884-2441, peterbrofman@gmail.com , or www.facebook.com/drpeterbrofman
4LEESBURG, VA:
Bush Advanced Veterinary Imaging,165 Fort Evans Road, Leesburg, VA 20176,
telephone 703-669-5544, website
www.bvns.net. Bush
Veterinary Neurology Service (BVNS) has provided this additional
information: "We offer Cavalier breeders MRI screening studies at a
discounted rate for non-clinical patients. Clinical patients must be
evaluated by a boarded neurologist first and would then receive a full study
rather than the discounted screening study. Owners can contact Bush
Veterinary Neurology Service to schedule appointments for clinically
affected patients at 703-669-2829. For multiple non-clinical patients, we
perform studies on Sundays once a month. The cost for the first patient is
$595.00 and subsequent patients are $575.00. We can accommodate 5
non-clinical patients on a Sunday. For single patients, we perform the
screening studies on weekdays at 8 am at a cost of $695.00. Owners will
receive a copy of the images on CD, an interpretation of the results from
one of our boarded neurologists, as well as instructions on how to contact
Dr. Rusbridge for additional information.
"Your pet will need to have minimum blood work performed by your
veterinarian within 7 days of the MRI screening at Bush Advanced Veterinary
Imaging. Please bring a copy of the blood work with you at the time of your
MRI screening appointment. The blood work should have, at minimum, a pack
cell volume (PCV), total protein (TP), blood urea nitrogen (BUN/Azostick),
and a blood glucose (BG) level." Additional information can be obtained
here. Board certified neurologists on staff are Drs.
William Bush, Joli
Jarboe, and Deena
Tiches.
4VIENNA, VA: AnimalScan at 328 Maple Avenue East, Vienna, VA 22180, telephone 703-281-9440, email vienna@animalscan.org See Easton, PA entry for details.
4UNITED KINGDOM: See the list of MRI clinics on the website of The Cavalier King Charles Spaniel Club at www.thecavalierclub.co.uk/health/syringo/mriscan.html
NOTE: If you know of other MRI clinics offering reduced rate scans or mini-scans for SM or CM, please let us know by emailing us at Editor@CavalierHealth.org
DNA Testing
Dr. Rusbridge
reported in May 2010 that genetic
researchers Quoc-Huy Trinh, Penny Knowler,
Alexandra
Thibault,
Marie-Pierre Dubé, Guy A. Rouleau, Clare Rusbridge, and Zoha Kibar may have found the site for SM on the cavalier's genome.
In a May 20, 2010 update on her website,
Dr. Rusbridge publishes an interim report in highly technical wording, which
states that they have located a haplotype which contains mutations in
SM-affected dogs and does not contain such mutations in unaffected
cavaliers. Gene sequencing and additional mapping of the locus are under way.
A team of Montreal researchers, including LeMay P, Trinh QH, Dubé MP, Rusbridge C, Rouleau GA, and Kibar Z, reported in June 2011 that they had identified a chromosome 2 region associated with Chiari-like malformation in the Brussels Griffon breed. See summary here.
Progression
SM is a progressive disease*, but its progression can be is extremely variable. Some cavaliers initially may exhibit no scratching or pain; others tend to scratch with only mild pain and no other neurological signs. For some dogs, the initial mild symptoms may never worsen. Other CKCSs can be severely disabled by pain and neurological signs within twelve months of the first signs developing.
* Chiari-like malformation (CM) also has been found to be progressive in some cavaliers.
Dr. Rusbridge stated in 2010, "In our experience, many cases of syringomyelia are not progressive, especially if the syrinx is small." In a 2011 study of 49 cavaliers, the UK researchers found that "the severity of SM was positively correlated with patient age. This is consistent with previous studies indicating that CKCS with SM were significantly older than dogs without SM (Couturier et al., 2008). It seems likely therefore, that SM is a progressive disease in dogs."
Clinical statistics show that about 45% of affected cavaliers develop signs of SM before their first birthday; another 40% will show symptoms between ages one and four years; the 15% balance develop signs later, with the oldest reported case of first developing symptoms at nearly seven years of age.
In a June 2011 study of 555 cavaliers without any symptoms of syringomyelia, 25% of the one year old dogs had SM and 70% of the dogs aged 6 years and older had SM.
In an October 2012 study by UK researchers of 48 cavaliers, nine of which had only CM and the rest had both CM and SM, neuropathic pain progressed in 75% of the dogs over a mean average period of 39 months. The researchers noted that it is not fully understood how CM/SM causes neuropathic pain, and they did not make any such finding.
In a November 2012 UK study by a team of veteran CM/SM researchers of 12 cavalier King Charles spaniels with Chiari-like malformation, they found that all of these conditions increased over time: syrinx width, height of the foramen magnum, length of cerebellar herniation, and caudal cranial fossa volume. The increase in the volume of the cranial fossa is believed to be due to resorption of the supraoccipital bone as syringomyelia progresses. They conclude: "We hypothesise that active resorption of the supraoccipital bone occurs due to pressure from the cerebellum. These findings have important implications for our understanding of the pathogenesis and variable natural clinical progression of CM and syringomyelia in CKCS."
This study confirms a finding in an October 2006 report by Dr. Clare Rusbridge and Penny Knowler that "on post-mortem examination, the supraoccipital bone overlying the cerebellar vermis is remarkably thin and sometimes eroded so that the foramen magnum is enlarged dorsally."
Treatment
The primary goal of treatment is to obtain relief from pain. Treatment options consist of drugs and surgery, as are examined in detail below. Dr. Rusbridge has prepared a diagram of treatment options, which she calls a treatment algorithm, which is downloadable here in pdf format
. Dr. Rusbridge stated in 2010:
"In our experience, many cases of syringomyelia are not progressive, especially if the syrinx is small, i.e. not every case with this disease needs be managed surgically and many do well on medical management, with drugs that reduce cerebrospinal fluid pressure (e.g. antacids such as cimetidine and omeprazole), non-steroidal anti-inflammatory drugs and adjuvant analgesics such as gabapentin (see Drugs, below). When the surgery for this disease has questionable long-term success it may be more appropriate to treat mild cases medically. As a rule I rarely use corticosteroids when treating spinal cord disease."
-- drugs
Treatment options for CM/SM are very limited. However, some medications
have been effective in some cases. The two photos to the right are
of the same cavalier King Charles spaniel. The photo on the left
shows the contorted face of a dog in severe pain. It was taken
before oral medication was administered. The photo at the right
shows the same dog, after oral medication has taken effect.
Photos from Dr. Clare Rusbridge
* Rimadyl may have serious side effects and should not be given without a veterinarian's close guidance and monitoring.
It has been reported that SM-affected cavaliers have been found to have a high level of inflammatory proteins in their bodies, and that for that reason, NSAIDs often provide some initial relief from pain. Also, doxycycline, a tetracycline antibiotic designed to treat bacterial infections, has been prescribed to CM/SM patients as an anti-inflammatory similar to NSAIDs.
Cortisteroids have serious side effects, such as weight, gait, and skin changes, and harmful suppression of the immune system. Long term use of these drugs is not advised.
NSAIDs and other conventional analgesic medications have not been found to be effective by themselves to relieve pain. Two 2007 studies (1) (2) show that the type of pain behavior suggests that the dogs experience neuropathic pain, probably due to disordered neural processing in the damaged dorsal horn, and that, "as such it is likely that conventional analgesic medication may be ineffective."
Anticonvulsants, such as
gabapentin (Neurontin, Gabarone), have been successful in some more
severe cases. Gabapentin works through a receptor on the membranes of brain
and peripheral nerve cells. It binds to
calcium
channels and modulates calcium influx as well as influences GABergic
neurotransmission. Its effect is to deaden the irritated nerve
impulses in the dog's neck. In humans, gabapentin reportedly does not
interact with any other medications, and it is not metabolized, so it is
fully excreted in the urine and has no affect upon the liver. However, in
dogs, gabapentin is partially metabolized in the liver, and therefore the
prescribing neurologist may be expected to order periodic blood tests to
check the liver enzymes.
In human studies, gabapentin has caused side effects, including sleepiness, dizziness, and leg edema, which were minimized by increasing the dose gradually and by taking the drug with food. WARNING: Beware of liquid formulations of gabapentin, which may include the sweetener xylitol, which is known to cause profound hypoglycemia and hepatic necrosis in dogs.
Gabapentin also may be given in combination with NSAIDs. It has been recommended that gabapentin be dosed once every 8 hours, as it lasts in the systems of most cavaliers that long.
A newer anticonvulsant, pregabalin (Lyrica), is being prescribed by some neurologists in treating SM. It is closely related to gabapentin and was developed by Pfizer, which also developed gabapentin. Pfizer reports that pregabalin is more potent than gabapentin and achieves its effect at lower doses. Doses of pregabalin also reportedly have a longer lasting effect than gabapentin. No generic version is available, and as an exclusive brand, Lyrica is quite expensive in comparison to generic gabapentin.
Amitriptyline (Elavil, Tryptizol, Laroxyl, Sarotex) is a tricyclic antidepressant (TCA) by Merck which may be prescribed as an alternative to either gabapentin or pregabalin.
Oral opioids (pethidine, methadone, tramadol) are alternatives to anticonvulsants. Methylsulfonyl-methane (MSM) is recommended by some veterinary neurologists as a dietary supplement.
Drugs which reduce the production of cerebrospinal fluid, including proton pump inhibitors such as omeprazole (Prilosec, Losec, Omesec, Zegerid), and the diuretics, furosemide (Lasix, Diuride, Frudix, Frusemide) and spironolactone (Aldactone), are reported to be useful to reduce intracranial pressure. Long term use of omeprazole is not recommended by some neurologists, as its long term use reportedly has increased the risk of stomach cancer in lab rats. Short term use reportedly can cause a "profound and sustained increase in serum gastrin concentration in dogs." See June 2011 report. Diuretics are being used infrequently, due to side effects and the success of other CSF pressure reducers.
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.
Neurologists have been prescribing cimetidine (Tagamet, Zitac), which is a histamine H2-receptor antagonist -- an antihistamine. Histamine contributes to inflammation and causes smooth muscles to constrict. Cimetidine is diffused into the cerebrospinal fluid and reportedly may contribute to reducing the flow of CSF. When taken with gabapentin, cimetidine also reportedly may increase the amount of gabapentin in the blood by decreasing its elimination. Therefore, when taken together, the dosages may require adjustment.
Some neurologists are prescribing amantadine (Symmetrel), which is used for control of the symptoms of Parkinson's disease in humans, together with gabapentin or pregabalin. Amantadine is believed to release brain dopamine from nerve endings making it more available to activate dopaminergic receptors.
Melatonin is a hormone produced by the pineal gland in the brain. Melatonin supplement has been prescribed by veterinarians to ease anxiety and restlessness in dogs. Some vets also have prescribed it for dogs with SM symptoms. Since melatonin is a hormone, it should not be given to dogs without the advice of a veterinarian. Melatonin can have adverse side effects, and in particular, it is contraindicated for dogs that are pregnant or lactating.
-- 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 (left), 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 (above right) provide relief.
-- surgery
The earliest reported surgeries to relieve CM was a series of suboccipital craniectomies and cranial dorsal laminectomies by a team of Belgium neurosurgeons in 2003. They had little success. Read their report here.
One form of surgery is called foramen magnum decompression (FMD), or suboccipital decompression, surgery. The surgeon removes the supraoccipital bone and the cranial dorsal laminae of the atlas. (See the decompression site over the occipital bone and foramen magnum, outlined in diagram at right.) Decompression surgery may include incising through the dura sac, a tough membrane which contains the brain inside of the skull, and installing a dural graft or shunt, to allow more space for the cerebellum and to reduce the pressure of the flow of CSF. In some surgeries, the entire occipital bone also is removed. A less frequent surgical procedure is subarachnoid shunting, which essentially is a salvage operation when the surgeon has no other surgical options. All FMD surgeries are technically difficult and should be performed only by experienced neurological surgeons.
Although this form of surgery often is successful, it may be expensive, and many dogs may either have a recurrence of the disease or still show signs of pain and scratching. Some post-operative pain is only temporary, due to leakage of CSF through the incision in the dura until that incision heals, or because the syrinx is still present after the surgery. The most frequent reason for recurrence reportedly is the development of post-operative scar tissue which compresses the cervicomedullary junction. Scar tissue has required additional surgery to remove it in about 25% of all FMD surgical cases. To avoid the development of scar tissue, it is important to not allow the dog too much freedom of movement or excitement during the healing process, which may last from three to six months.
In an effort to prevent such scar tissue from
re-compressing the junction, modified versions of FMD include
inserting
either a skull plate made of titanium mesh at the junction before closing
the incisions, (see photo), or covering the sutured dura with a tented graft
of swine intestine tissue, covered by a layer of the dog's fat tissue.
Decompression surgery is not expected to cure the SM. It is intended to reduce the pressure and stop the progression of the syrinxes. Damage done to the brain and spinal cord before the surgery usually will not be reversed, and most dogs will need to continue on medications afterwards, including gabapentin or pregabalin and cortisteroids, depending upon the severity of that damage before the surgeries. The neurologists also may recommend that the post-surgery patient undergo rehabilitation physical therapy, in part to offset debilitating effects to the muscles, which may result from long term doses of cortisteroids.
--- cranioplasty using titanium
The titanium procedure is called cranioplasty. Dr. Curtis W. Dewey, veterinary neurologist in New York, and Dr. Dominic J. Marino, board certified veterinary neuro-surgeon, also in New York, and Dr. Wayne L. Berry, veterinary neurologist in California inserting the titanium mesh in several surgeries thus far. And now other specialists, including Dr. Graham Oliver in the UK, are performing the cranioplasty procedure.
In a report published in July 2007 in Veterinary Surgery, Drs. Dewey and Marino wrote: "Foramen Magnum Decompression (FMD) with cranioplasty was well tolerated, with no intraoperative complications, and minor postoperative complications. Most dogs improved clinically, and none required further surgery at the original FMD site." Dr. Dewey also has reported that the "re-operation rate" has been reduced to 10% or less of all FMD surgeries with the titanium mesh cranioplasty. See more about Drs. Dewey and Marino under Current Research below.
--- cranioplasty using LactoSorb SE mesh
LactoSorb SE mesh is a biodegradable polymer designed to resorb in the human body by hydrolysis within a year. Dr. Thomas Schubert at the University of Florida has tried it instead of titanium mesh in cranioplasty surgeries performed on cavaliers. He since has switched back to using the titanium mesh, and he is waiting for more information on the long term results of surgeries using LactoSorb SE mesh. This product reportedly is equal in strength to titanium at initial placement, retains 70% of its initial strength for the first eight weeks, and then gradually is eliminated from the body. It is manufactured by Biomet Microfixation, LLC of Jacksonville, Florida.
--- duraplasty using swine tissue
The alternative of a tent graft of swine tissue and body
fat is called duraplasty.*
Dr. Andy Shores,
veterinary
neurologist at
Mississippi State University (previously at Auburn in Alabama), Dr. Jill
Narak, veterinary surgeon at the University of Tennessee in
Knoxville, and others have performed this procedure on at least 21 dogs,
most all of them cavaliers. Swine
intestinal submucosa was sutured over the cerebellum and brain stem in a
tented fashion (see photo). Fat tissue from the dog's gluteal region was then placed
over the site prior to routine closure.
* It is called duraplasty because the tissue is used as a substitute to the portion of the dura which was cut during the surgery.
In a report published in October 2009 at the American College of Veterinary Surgeons' annual symposium, the researchers stated: "Overall, recovery was considered to be good to excellent by owners. To date, none of the patients that have undergone this surgical procedure have required further surgical intervention due to postoperative compressive scar formation that has been reported in the previous literature. Follow-up time ranges from 1 week to 1 year. ... The use of the titanium mesh, placement of the screws, and the exothermic reaction of the overlying methyl methacrylate may contribute to tissue trauma. The authors conclude that with the results of this study, this procedure is clinically effective and the use of a titanium mesh, additional hardware and methyl methacrylate offers no advantage in canine COMS patients."
--- duraplasty using tissue adhesives
Synthetic dural substitutes in duraplasty procedures include inserting a soft foam consisting of a collagen-based matrix (e.g., DuraGen, by Integra LifeSciences Corporation). The collagen matrix supports the ingrowth of local cells while the matrix itself is fully resorbed over time. Dr. Michael Harrington, Animal Neurosurgery and Neurology, Murray, Utah, reportedly uses this technique.
--- syringosubarachnoid shunt
The shunt consists of a small silicone tube. One end is inserted into the subarchnoid space of the spinal cord below the syrinx, and the other end is inserted into the syrinx (see below, left). Thus it is called a syringosubarachnoid shunt (S-S shunt). Shunting drains the syrinx fluid into the subarachnoid space where the usual CSF circulation and absorption mechanisms exist. This should reduce the size of the syrinx and ease pain and other the clinical signs associated with CM/SM.
In
an April 2012 study of S-S
surgeries conducted on nine cavaliers and two Yorkshire terriers, Geoff
Skerritt and Dr. Luca Motta reported that:
"S-S shunting is a safe and relatively effective surgical technique that may improve the neurological signs and the quality of life of dogs affected by CM and associated SHM/SM. Postoperative complications or lack of clinical improvement may occur in a small number of cases and a secondary surgery may be needed. This study also suggests that the S-S shunt may lead to a satisfactory outcome in dogs where the FMD [foramen magnum decompression] technique has failed. Comparisons between different surgical techniques are needed to create objective criteria that may suggest which procedure will produce the best surgical results."
Mr. Skerritt and Dr. Motta may be contacted at ChesterGates Animal Referral Hospital, Telford Court, ChesterGates, Chester, UK, CH1 6LT, telephone 01244 853823, email GCSkerritt@aol.com.
--- conclusion about surgeries
Many of these studies have been "case studies", meaning that they were practiced without the controls normally included in clinical trials. In the July 2007 issue of Veterinary Surgery, Dr. Richard A. LeCouteur, board certified veterinary neurologist at the University of California, writes that "Medical history is replete with examples of invasive procedures and pharmacologic interventions that were widely accepted based on results of case studies, only to later be rejected based on results of controlled clinical trials. ... It’s time to adopt a more structured scientific approach to the study of the management of neurologic conditions that may benefit from surgical intervention. The randomized (preferably) double-blinded (preferably) placebo-controlled study is the gold standard for evaluating a new treatment intervention."
-- post-surgery soundwave therapy
Some cavalier King Charles spaniels, which have continued to suffer
severe pain due to post-decompression surgery scar tissue, have been
very successfully treated with an infrasonic instrument called AlphaSonic™.
This infrasound technology generates multiple, random, chaotic sound waves
in the range of Alpha (approximately 8 to 14 Hz), and unlike ultrasound
waves, does not heat body tissue. Ultrasound uses a single high
frequency (from 20,000 to1,000,000 Hz) to stimulate a localized area and
heats tissue.
The manufacturer of the device represents that AlphaSonic™ is safer and more effective than ultrasound, penetrates deeper into the tissues, reduces inflammation, and softens scar tissue. It can be applied locally and at acupressure points, and is said to increase blood circulation and can allow the body to heal itself, much like the affects of acupuncture, but without the needles.
The device is electrically operated and looks very similar to an ultrasound unit. Dr. Ronald J. Riegel, DVM, who has studied the effects of the AlphaSonic™ since 2001, stated, "The goal of any physical therapy modality is to increase the circulation and increase the elasticity and flexibility of the tissue. the alphasonic absolutely increases circulation and allows the body to heal itself. The metabolism is increased, reducing recovery times".
Adequate hydration is important for optimum bodily function. The dog should be kept hydrated before, during, and after treatment with fresh clean water. Although the manufacturer reports that AlphaSonic™ is totally safe and that no negative side effects are known, any AlphaSonic™ treatments for dogs with veterinary conditions, especially those taking medication, should be performed only under the guidance of a qualified, licensed veterinarian. For more information about AlphaSonic™, contact Susan Stoltz at AlphaSonic, P.O. Box 2727, Valley Center, CA 92082, telephone 760-751-2836, email alphasonics@sbcglobal.net, websites www.alphasonic.com and www.makepaingoaway.com
Breeders' Responsibilities
SM has a tendency to be more severe in each subsequent generation, and with an earlier onset. Breeders should follow the SM Breeding Protocol.
What You Can Do
4Donate by buying For the love of Ollie.
4
Participate 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 neurovet@virginmedia.com, 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 neurovet@virginmedia.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.
Research News
4May
2013: CM/SM Trust website is up. The website of the CM/SM
Trust's canine chiari and syringomyelia research is up and running.
Click here. It
provides information about CM/SM in both humans and dogs and is worth a good
long look. There is extensive information about research projects, upcoming
events, biographies of leading researchers and supporters, where and how to
contribute, and even a gift shop.
4May
2013:
UK
Kennel Club announces syringomyelia as a "candidate" for EBVs.
The UK Kennel
Club, in its
2012 Dog Health Group Annual Report, announced that syringomyelia (along
with mitral valve disease) "are candidates for the development of EBVs
[estimated breeding values] but require appropriate data collection
procedures to be in place." The report goes on:
"A BVA/KC scheme for syringomyelia was launched in 2012 and once enough data has accumulated through the scheme then EBVs for the condition will become a possibility."
For more information about EBVs, see our webpage on the topic.
4April 2013:
German researchers find relationship between pain and asymmetrical syrinxes
and dorsal horn involvement in cavaliers with SM. In
a 2013
study of 26 cavaliers (11 dogs without clinical signs of pain; 6 dogs
with pain and symmetrical syrinxes; 9 dogs with pain and asymmetrical
syrinxes), German researchers found "an association" between pain and SM
asymmetry, and they found "a strong association" between pain and dorsal
horn involvement of SM. CKCSs with clinical signs of pain showed either
asymmetrical
syrinxes or involvement of the dorsal horn gray matter. They also found that
cavaliers with clinical signs of pain showed a presence of interleukin-6 (a
key component of the nervous system’s response to injury) and substance P (a
neurokinin that regulates the immune functions of spinal glial cells) in
their cerebrospinal fluid (CSF). The researchers conclude that the release
of interleukin-6 and substance P is a factor in the development of
persistent pain in cavaliers with SM. They suggest that this information
could offer new diagnostic and treatment options for CKCSs with SM. (In
the study's photo above, the top three syrinxes are asymmetrical; the bottom
three are symmetrical.)
4February 2013: UK neurologists report cavaliers' CM/SM may either result from independent development of the occipital bone and cerebellum or dysregulation of a growth mechanism signal. In a February 2013 report, UK researchers T. A. Shaw, I. M. McGonnell, C. J. Driver, C. Rusbridge, and H. A. Volk compared MRI scans of 45 CKCSs, 38 dogs of other small breeds, and 26 Labrador retrievers, and concluded:
"The data support the hypothesis that CM/SM in CKCS is a multifactorial disease process governed by the effects of increased hindbrain volume and impaired occipital bone development. The present authors recently reported that CM/SM is linked to increased cerebellar volume (Shaw and others 2012). In view of this, the aetiopathogenesis of CM/SM may equivocally be mediated by conditions independently affecting the developing occipital bones and cerebellum, or by dysregulation of a signalling mechanism coordinating the growth of the developing hindbrain and occipital skull."
4January
2013: UK's
Bristol University seeks CKCS head size data worldwide for The
Conformational Indicators Study. Thomas Mitchell,
Bristol University researcher, has announced that
The Conformational Indicators Study (of whether there is a relationship
between head size and shape and CM or SM) now can accept shape and size data
from cavaliers worldwide via a new website.
Mr. Mitchell states:
"We are now at the point where we can progress the research further and collect some data internationally for analysis and discussion. We have compiled an instruction manual of measurements that everyone can follow, and we have a fancy webpage where everyone can input the information. By doing this, we will be able to get some definitive answers for the questions that have been brought up here and validate some of our theories! I have already been hard at work taking measurements in the UK to contribute and likewise Henny in the Netherlands, and we will continue to do so; however, this part of the study will allow for people to contribute measurements of all their MRId dogs worldwide! Of course - I will be able to measure the UK dogs, so anybody who wishes to get involved in the UK can contact me directly to organise a visit by email at cmsmresearch@gmail.com The best thing about this study is that it is going to give all breeders an evidence base to work from in choosing what conformation they want to strive for - hopefully one that will enable better results upon health testing - long in advance of matings, etc."
The instructional guide for compiling the data is at www.cmsmtrust.org/resources/Catalogue-of-Measurements.pdf The data may be input on an on-line measurement collection form here: www.cmsmtrust.org/page31/page47/Mes/index.php
4January 2013: US neurologists need previously MRI'd cavaliers for brain/skull size study. Dr. Sofia Cerda-Gonzalez of Cornell University in New York and Dr. Natasha J. Olby of North Carolina State University are performing a study looking into the relationship between brain structure/skull size and clinical changes (development, worsening, or absence of clinical signs) in cavalier King Charles spaniels. This study will help to better understand which, if any, MRI findings are predictive of a cavalier developing new or more pronounced clinical signs in the future. Such information is crucial to understanding the clinical significance of imaging findings and being able to make more informed treatment decisions for Cavaliers.
As such, they are inviting owners of CKCSs that have had an MRI of their brain and/or neck performed four or more years ago to participate in this effort. Through the study, they will provide a no-cost MRI of the brain and neck to a limited number of cavaliers. Owners of participating dogs will be asked to fill out a simple questionnaire, and will be provided with the results MRI imaging at the time of participation. If you are interested in participating, contact Dr. Cerda-Gonzalez at sc224@cornell.edu or at 607-253-3060.
4November
2012:
UK clinic studies thermal imaging to detect CM/SM.
Stephanie Godfrey of
Veterinary Thermal Imaging Limited in Churt, Surrey, UK is
studying
thermal imaging of dogs to detect Chiari-like
malformation and syringomyelia. She states:
"A study came to my attention from an American Veterinarian, Dr. Dominic Marino. A preliminarily study was carried out to establish if a thermographic imaging protocol would be feasible for dogs suspected of having Chiari- Like Malformation (CLM). The preliminarily results have shown that dogs with abnormal MRI findings revealed a 'cooler thermographic pattern' compared to those with normal MRI results. This suggested that thermal imaging may be a useful imaging modality for the screening of CLM detection in dogs. As a veterinary thermographer, I decided that I would like to trial a study over here in the UK to see if this 'cooler reading' would show a correlation to the MRI findings."
The procedure used to explore the use of thermal imaging for the screening of CLM is non-invasive. Thermal images are taken of the dog's head and neck. The images can be taken without the need for sedation, and in the dog's home. The thermographer then examines these images, along with MRI results, to see if a correlation can be seen between skull and neck structures in the affected animals.
Veterinary Thermal Imaging Limited is located on Hale House Lane, Churt, Surrey, GU10 2JG. For more information, contact Stephanie Godfrey at Stephanie.godfrey@vtiuk.com, telephone 0844 544 3314, website www.veterinary-thermal-imaging.com
4November
2012: German researchers assess effect of gabapentin on
post-operative pain after
intervertebral disc surgery. In
a
November 2012 report in Veterinary Anaesthesia and Analgesia, involving 63
dogs, German neurologists compared the pain-relief value of gabapentin when
added to opioid analgesia. They concluded that gabapentin administered
orally twice a day "did not result in a detectable reduction in pain
behaviour compared to background opioid analgesia alone." However, they
recommend further studies to determine if the results were related to
effective background analgesia or an ineffective dose of gabapentin.
4October 2012: UK researchers conclude that neuropathic pain progresses in 75% of CKCSs with CM and/or SM. In an October 2012 study by leading UK CM/SM researchers, they studied the clinical signs of neuropathic pain in 48 cavalier King Charles spaniels for a mean average of over a three year period. Nine of the 48 dogs had only CM. None had been treated surgically. They found that the clinical signs suggest that neuropathic pain progressed in 75% of the dogs with either CM/SM or just CM. They noted that it is not fully understood how CM/SM causes neuropathic pain, and that their study does not make any such finding.
4October 2012: UK's Penderis views CKCS's high prevalence of CM and limited genetic diversity as "major difficulties". In an editorial in the Veterinary Journal, UK researcher Dr. Jacques Penderis comments upon recently reported research into Chiari-like malformation and syringomyelia in the cavalier King Charles spaniel. He concludes:
"The high prevalence of Chiari-like malformation in the breed and the confirmation that brain morphology is directly influenced by head phenotype (Hussein et al., 2012), suggests that Chiari-like malformation in the CKCS is likely to be the inadvertent consequence of misguided breeder selection to emphasise certain cranial features deemed to be desirable. The high breed prevalence of Chiari-like malformation (estimated at 95%) points to limited genetic diversity within the CKCS, resulting in major difficulties if breeding away from conformations associated with Chiari-like malformation is attempted in the future."
4October
2012:
UK's Bristol Univ. plans study of cavaliers' head shapes for CM/SM
characteristics. Thomas Mitchell, a researcher
at the University of Bristol, in Bristol, UK, seeks to answer the common
question, "Can you tell if a dog has CM or SM by looking at it?"
He heads "The Conformational Indicators Study" and is
investigating the extent to which conformational characteristics -- the
external appearance of dogs, such as head shape -- indicate the presence of
Chiari-like malformation (CM) and/or syringomyelia (SM). The study seeks to
determine if aspects of the conformation are risk factors for CM/SM. This
may identify an additional method of indicating disease by measuring the
head and body of the dogs, and thereby enable cavalier breeders (and Griffon
Bruxellois breeders) to identify which prospective breeding stock to scan
and perhaps allow breeders to decide on future matings based upon the
overall conformation of the dog and not only on the results of MRI scans.
Breeders of cavaliers with current MRI certificates are being sought to aid this study. All information obtained in the study will be kept confidential, and privacy will be maintained throughout the study. First, the participating breeders are asked to submit their dogs' MRI certificates to a confidential email address, fax number, or postal box. A trained researcher would visit the breeders' premises (or dog show or other breed event) and take a series of non-invasive measurements. A unique ID number will be assigned to each dog, so that the researcher will not know in advance the MRI status of the dog. The ID number also will provide owner confidentiality.
If you are a cavalier breeder and are willing to participate or have questions, contact Thomas Mitchell at CMSMresearch@gmail.com or join the group's Facebook page. See also Dr. Clare Rusbridge's blog article for more information.
4September 2012: UK researchers find that CKCSs with SM have narrower jugular foramen than unaffected CKCSs. In a September 2012 report, a team of UK researchers compared 20 cavaliers with SM and 20 without SM and found that the jugular foramen (a space between the temporal bone and the occipital bone, containing the jugular vein), was narrower in the SM-affected cavaliers. They concluded that the narrower gap of the jugular foramen in SM-affected CKCSs may affect the pressure waves of cerebrospinal fluid (CSF) and serve as an additional factor (other than cerebellar herniation) causing SM.
4July 2012: Australian vet surgeons find cavalier with life-threatening dysphagia caused by Chiari-like malformation. A team of Australian veterinary surgeons report of foramen magnum decompression surgery resolving a cavalier King Charles spaniel suffering from life-threatening dysphagia (difficulty in swallowing food caused by disease or impairment of the nervous system). They conclude that CM can be a cause of dysphagia in dogs.
4July 2012: UK researchers find no connection between Chiari-like malformation and epilepsy in cavaliers. In a 2012 report in the Veterinary Journal, UK neurology researchers C.J. Driver, K. Chandler, G. Walmsley, N. Shihab, and H.A. Volk examined the MRIs of 85 cavalier King Charles spaniels, looking for a relationship between Chiari-like malformation (CM), ventriculomegaly, and seizures in the dogs. The 85 CKCSs all had CM; 27 of them also had had seizures. They found no association between CM, ventriculomegaly, and the seizures. The seizures were classified as having partial onset -- meaning that they occur in in one area of the brain, unlike generalized seizures which typically affect nerve cells throughout the brain -- in 61% of the dogs. They also stated that "Another cause of recurrent seizures in CKCS (such as familial epilepsy) is suspected, as previously reported."
4July 2012: International neuropathic pain study is completed; results are awaited. A multi-school clinical study evaluating the efficacy of a novel treatment for the control of pain associated with syringomyelia in cavalier King Charles spaniels has been completed, We first reported this study in November 2007. The study was part of a collaborative effort between a pharmaceutical company, and the vet schools at the UK's Royal Veterinary College, the University of Pennsylvania, and the University of Minnesota. The study recruited patients from November 2007 to October 2008 and after screening 119 dogs, a total of fifty two patients participated in the trial. Following statistical analysis, the report is that the results are promising, and that there is potential for further development of this new medication to help alleviate the pain associated with syringomyelia.
4July
2012: UK Kennel Club adds a CM/SM recommendation for
cavaliers to its Assured Breeder Scheme. Effective July 1,
2012, the UK Kennel Club's
Assured Breeder Scheme recommends that all CKCSs being bred
first comply with the
BVA/KC
Chiari Malformation/Syringomyelia Scheme breeding guidelines.
This is not a mandatory requirement for participants of the
Assured Breeder Scheme.
4June
2012:
UK researchers report results of questionnaires on neuropathic pain in
CM/SM-affected cavaliers. In a
2012 study, UK
researchers (Lynda Rutherford, Annette Wessmann, Clare Rusbridge,
Imelda M. McGonnell, Siobhan Abeyesinghe, Charlotte Burn, and
Holger A. Volk). of cavaliers with neuropathic pain report on the
results of extensive questionnaires completed by the owners of 122
CM/SM-affected CKCSs. They found that owners who noticed evidence of
neuropathic pain in their dogs also found the dogs to have increased
fear-related behaviors (such as acting more fearfully when approached by
strangers, or when in unfamiliar situations, or when sudden loud noises
occurred, such as thunderstorms). These dogs also were more clingy to their
owners and appeared to be more fearful when left alone. They also showed
decreased willingness to exercise, and problems in settling, including sleep
disturbances. Not surprisingly, the study also showed that owners found that
their affected dogs had reduced quality of life.
4June
2012: German researchers dispute
that cavaliers have Chiari-like malformation. In a
June 2012 report in
Veterinary Radiology & Ultrasound, German neurologists and radiologists
Martin J. Schmidt, Martin Kramer, and Nele Ondreka
compared the volumes of occipital bones of cavaliers with and without
syringomyelia and of French bulldogs. They did not find a reduced volume of
the occipital bone of CKCSs,
compared to the bulldogs. They concluded:
"These results do not support occipital hypoplasia as a cause for syringomyelia development, challenging the paraxial mesoderm insufficiency theory. This also suggests that the term Chiari-like malformation, a term derived from human studies, is not appropriate in the Cavalier King Charles spaniel."
The authors of this article seemed mired in the pre-2010 definition of Chiari-like malformation. They state:
"... [T]he Chiari-like malformation in the Cavalier King Charles spaniel is characterized by indentation of the occipital (bone) with cerebellar herniation and is more correctly termed caudal occipital malformation syndrome."
They also appear to be unduly dismissive of the studies beginning in 2009 which found that the cavalier's cerebellum is relatively larger than that in other breeds. The authors of this June 2012 article did not include cerebellum size in their study, and their comment about the 2009-2012 reports simply is:
"Results of studies proposing a mismatch between cerebellar and caudal cranial fossa volume in this breed and in comparison to other breeds were controversial. In some studies, there was a mismatch between caudal fossa parenchyma and caudal fossa volume in dogs with syringomyelia and overcrowding was proposed as a cause of syringomyelia development. In most studies, however, no difference was found between caudal fossa volume in Cavalier King Charles spaniels with and without syringomyelia, although this was not universal." (Emphasis added.)
4April
2012: RVC to compare
chicken and mouse cerebellar development with that of CKCSs.
Royal Veterinary College researchers Dr. Imelda McGonnell
and Dr. Holger Volk plan to investigate
cerebellar
development in various chicken, dogs and mouse models, in hopes that this
research will lead to a better understanding of the Chiari-like malformation
disease process and provide therapeutic targets. This project is being
jointly undertaken in the laboratories of Drs. McGonnell and Volk at the RVC
and Dr. Albert Basson at the Dept Craniofacial Development, Kings College
London, and is being funded by the Wellcome Trust. Read more
here.
4April 2012: UK researchers find an association between syringomyelia and the cavalier's oversized cerebellum. In an April 2012 report, UK researchers Thomas A. Shaw, Imelda M. McGonnell, Colin J. Driver, Clare Rusbridge, and Holger A. Volk, confirmed previous studies that cavalier King Charles spaniels have proportionately larger cerebellums than other small breeds and Labradors. They also found an association between the CKCS's oversized brains and SM. 75 cavalier MRI scans were reviewed. They concluded:
"These findings support the hypothesis that it is a multifactorial disease process governed by increased cerebellar volume and failure of the CCF to reach a commensurate size."
4April 2012:
RVC needs cavaliers to compare neuropathic pain medications for SM.
The Royal Veterinary College is seeking UK and US cavaliers diagnosed with
symptomatic CM and/or SM to participate in a study comparing two neuropathic
pain medications. Eligible dogs must show clinical signs of neck/ back pain,
air scratching, facial rubbing, screaming/ yelping episodes or wobbliness.
Dogs with kidney or gastro-intestinal disease cannot be included.
The RVC and the Queen Mother Hospital Royal Veterinary College and Queens Veterinary School Hospital and Stone Lion Veterinary Group, all in the UK, as well as the College of Veterinary Medicine, Iowa State University, in Ames, Iowa USA, are participating. For more information, email tckcstrial@gmail.com or click here.
4April 2012: Geoff Skerritt and Dr. Luca Motta find shunt surgery successful for relieving SM pain. UK neurosurgeons Geoffrey Skerritt and Dr. Luca Motta report in an April 2012 study that:
"[Syringosubarachnoid shunt] S-S shunting is a safe and relatively effective surgical technique that may improve the neurological signs and the quality of life of dogs affected by CM and associated SHM/SM. Postoperative complications or lack of clinical improvement may occur in a small number of cases and a secondary surgery may be needed. This study also suggests that the S-S shunt may lead to a satisfactory outcome in dogs where the FMD [foramen magnum decompression] technique has failed. Comparisons between different surgical techniques are needed to create objective criteria that may suggest which procedure will produce the best surgical results."
The researchers performed surgeries on nine cavaliers and two Yorkshire terriers. Ten of the dogs survived the study. They also devised a Pain Score Scheme (see table above under Symptoms) to evaluate the levels of pain the dogs experienced both before and following the surgeries.
4March
2012: UK's BVA and KC issue CM/SM breeding guidelines. The British Veterinary Association (BVA) and the UK's Kennel
Club (KC) issued in March 2012 a set of
Chiari-like malformation
and syringomyelia (CM/SM) breeding guidelines,
with the aim of removing from breeding programs, cavalier King Charles spaniels
with early-onset SM, and thereby reducing or even eliminating the incidence of
CM/SM in future generations of cavaliers. This SM
breeding protocol is limited to cavaliers (and other breeds) registered with the
UK's Kennel Club. The two USA national cavalier clubs have refused to
acknowledge the existence of any SM breeding guidelines, and the US clubs place
no restrictions on breeding cavaliers with CM/SM.
4December
2011: The Cavalier Foetal Tissue Research Project's website is
online. Sheena Stevens has created a website about the Cavalier
Foetal Tissue Research Project:
http://www.ftrproject.com Check it out to learn more about this research
program and how to contribute funds to it. Also, read more about the project
here.
4December 2011: UK researchers confirm that cavaliers with only CM suffer pain and that CM/SM is progressive. In a December 2011 study at the Royal Veterinary College, researchers studied 49 clinically affected CKSCs. They found: (a) 25% did not have SM; (b) the severity of SM was positively correlated with patient age; and (c) there is a very high potential for CKCS with clinical signs of CM/SM to develop SM in more than one spinal cord region.
4October 2011: Univ. of Penna. cardiologists study torsemide as alternative to furosemide. University of Pennsylvania veterinary cardiologists report that they have tested the loop diuretic torsemide as alternative to furosemide in dogs with advanced heart failure, including a 12 year old cavalier. They have found torsemide "has several characteristics that make it suitable for treatment of advanced heart failure including longer half-life, increased potency of diuretic action, and anti-aldosterone effects."
4October 2011: SM Breeding Protocol Statistics. In an October 2011 report of the statistical results of following the SM protocol, the researchers, Dr. Rusbridge, Penny Knowler, and A. K. McFadyen stated that:
"This study investigated the early outcome of existing SM breeding guidelines. Six hundred and forty-three dogs, 550 Cavalier King Charles spaniels (CKCS) and 93 Griffon Bruxellois (GB), were identified as having either one (454 dogs) or both parents (189 dogs) with MRI-determined SM status.
• Offspring without SM were more common when the parents were both clear of SM (SM-free; CKCS 70 per cent, GB 73 per cent).
• Conversely, offspring with SM were more likely when both parents had SM (SM-affected; CKCS 92 per cent, GB 100 per cent).
• A mating of one SM-free parent with an SM-affected parent was risky for SM affectedness with 77 per cent of CKCS and 46 per cent of GB offspring being SM-affected.
It is recommended that all breeding dogs from breeds susceptible to SM be MRI screened; that the SM status at five years old is established; and all results submitted to a central database that can be used by dog breeders to better enable mate selection based on estimated breeding values."
4September 2011: UK researchers examine distribution of pain-related neuropeptides in cavaliers with SM. They observe that CKCSs with clinical signs of SM also show disruption in the structure of their spinal cord's dorsal horn. See report summary. The researchers conclude:
"This current study provides evidence to suggest that the disruption of the dorsal horn structure is a significant event in the production of clinical signs in CKCS. The spinal cord dorsal horn in symptomatic CKCS is significantly more asymmetric than that of control animals, whereas the asymptomatic CKCS have changes that are midway between control and symptomatic CKCS. This suggests the possibility that progression from mild to severe asymmetry in CKCS is associated with development of clinical signs; however such a conclusion cannot be definitively supported by this study because of the cross sectional nature of the data collected."
4September 2011: Researchers find that SM is associated with degenerative changes in the spinal cord. In a study published in the Journal of Comparative Pathology, researchers H.Z. Hu, Clare Rusbridge, F. Constantino-Casas, and Nick Jeffery report that:
"SM is associated with degenerative changes in the spinal cord and may develop through primary disruption of ependymal integrity followed by vascular hypertrophy and proliferation. Glial and fibrous proliferation appears to be associated with expression of clinical signs."
The ependyma is the epithelial membrane which lines the spinal cord. Vascular hypertrophy means the increase in the volume of blood vessels. Glial are cells that provide protection for the brain's neurons, among other things.
Commenting on the findings by one of the article's authors, Dr. Clare Rusbridge, she writes on her blog:
"The pathology suggested that the primary development of syringomyelia is associated with central canal dilatation and damage which is accompanied by blood vessel changes. This is an important finding because there is so much debate on how syringomyelia develops in all species."
4August 2011: Head position affects extent of cerebellar herniation in MRI scans. UK researchers examining 14 CKCS MRI scans (7 with CM/SM and 7 with just CM) comparing scans in both extended and flexed head positions. In their report, they have found the degree of cerebellar herniation was significantly worse in dogs with a flexed compared to an extended head position. When cerebrospinal fluid (CSF) space between the cerebellum and brainstem was compared in CKCS with and without SM, there was a significant increase in CSF space in CKCS with CM alone compared to those with CM/SM when head position was flexed. Based upon their findings, they state that it may be appropriate to position patients in a more flexed head position for optimal imaging in order to identify morphologic changes more accurately. They stated that this is important to consider for imaging CKCS with CM especially when studying the pathogenesis of CM/SM.
The researchers also found:
"When CSF space between the cerebellum and brainstem was compared in CKCS with and without SM, there was a significant increase in CSF space in CKCS with CM alone compared to those with CM/SM when head position was flexed. In their cine MR imaging study of CSF flow dynamics in CKCS with CM or CM/SM, Cerda-Gonzalez and others (2009a) found that turbulent CSF flow and jets are associated with SM presence and severity and CSF flow velocity at C2/3 is inversely related to the presence of SM. The reduced CSF space in CM/SM dogs reported in this study could explain this jet like CSF flow in dogs with CM/SM compared to those with CM alone."
This could mean that the severity of CM/SM, or even the presence or future presence of SM, could be predicted based upon the measure of cerebrospinal fluid space between the cerebellum and the brainstem. If so, this could go a long way to distinguishing whether a CM-only cavalier is either likely or unlikely to develop SM in the future. This distinction could be a way to fine-tune a breeding protocol, considering that we now know that over half of cavaliers with SM develop it after their 3rd birthday. If we could reliably count on this measurement of CSF space to tell us if a young dog will, or will not, develop SM in the future, then we could more reliably select SM-free breeding stock at a younger age than the present 2.5 years and the 3+ years the researchers may recommend in the future.
4June 2011: Montreal team of researchers identify chromosome 2 region associated with Chiari-like malformation in the Brussels Griffon breed. See summary here. Researchers include Lemay P, Trinh QH, Dubé MP, Rusbridge C, Rouleau GA, and Kibar Z.
4June 2011: UK researchers find that CM is progressive in CKCSs; that foramen magnum size and cerebellar herniation increase significantly. UK researchers, including Drs. Rusbridge, Driver, and McGonnell, reported to the ACVIM in a June 2011 study that twelve CM-affected cavaliers' foramen magnums and the length of cerebellar herniation "increased significantly" between MRI scans which averaged 9.5 months apart. they concluded:
"This work could suggest that overcrowding of the caudal cranial fossa in conjunction with the movements of cerebrospinal fluid and cerebellar tissue secondary to pulse pressures created during the cardiac cycle causes pressures on the occipital bone. This leads to a resorption of the bone and therefore an increase in caudal cranial fossa and foramen magnum size allowing cerebellar herniation length to increase."
4June 2011: UK researchers report CKCS has relatively larger cerebellum than both small breeds and Labradors. In a June 2011 report to the ACVIM, UK researchers, including Drs. McGonnell, Driver, and Rusbridge, compared cerebellar size of cavaliers with other small breed dogs and with Labrador retrievers. They conclude: "Our findings show that the CKCS has a relatively larger cerebellum than small breed dogs and Labradors and there is an association between increased cerebellar volume and SM in CKCS."
4June 2011:
Long Island Veterinary Specialists report 97.3%
accuracy in thermography diagnosing Chiari-like malformation in CKCSs.
Drs. Catherine Loughin and Dominic Marino released a
June 2011 study of 105 cavaliers,
comparing the results of medical infrared imaging (MII), also called
thermography, with MRIs to detect the presence of CM. The results: "The top
of head and front of head ROI [regions of interest] were 89.2% and 97.3%
successful in identifying dogs with CLM. Based on these preliminary
findings, MII may be a viable screening tool to detect CLM in dogs."
Thermography does not require sedation.
4June 2011: Omeprazole profoundly increases dogs' serum gastrin concentration in two weeks. US researchers studying the effect of two weeks of omeprazole doses on healthy dogs reported "a profound and sustained increase in serum gastrin concentration in dogs. This effect is rapidly reversible after cessation of the treatment. No effect on calcium metabolism was observed."
4June 2011: Alastair Cockburn to study pain due to SM. The Universities Federation for Animal Welfare (UFAW) has awarded a Research Training Scholarship to Alastair Cockburn of the University of Bristol. He will investigate methods for assessing pain, underlying emotional state and quality of life in dogs with chronic pain conditions of syringomyelia and osteoarthritis. The aim of the research project is to deliver a useful clinical tool to measure chronic pain in dogs, a problem area due to the often very subtle changes in behavioral indicators of pain and the difficulty of assessing underlying emotional state and cumulative experience of pain – factors of critical importance in assessing quality of life.
4June 2011: UK study of 555 cavaliers shows percentage with SM up to 70% in older dogs with no symptoms. A UK study of 555 (reportedly) asymptomatic CKCSs found 25% of 12 month olds with syringomyelia, increasing to 70% in cavaliers 6 years and older. The researchers concluded:
"The evidence for a lower prevalence in younger animals is more reliable (because of the higher numbers included in the present study and the lower likelihood of false inclusion) and this effect lasts until dogs are at least three years of age. This finding has important implications for the design of a screening test procedure and may conflict with the current recommendations that the optimum age for screening should be 30 months. These data would imply that it is probable that dogs aged up to three years may yet have reduced odds for the diagnosis of syringomyelia. However, there is a need for the dogs to be creened when they are reasonably young so that breeders can decide at an early stage whether their animals are suitable for breeding; many breeders would consider 36 months unduly old. ... The high lifetime prevalence of syringomyelia raises concerns for the welfare of the CKCS breed and also suggests that eliminating the genetic risk factors for the disease by selective breeding may be difficult, because the heritability has previously been shown to be complex, and the prevalence of the determinant genes within the population is therefore likely to be high. The true prevalence of syringomyelia in the general CKCS population is expected to be higher than that found in this sample population because symptomatic dogs were specifically excluded."
4May 2011: Somatosensory-evoked potentials' (SEP) amplitude is more sensitive measure of spinal cord function in CKCSs with SM. UK researchers report that SEP amplitude at the C1 vertebra was a more sensitive measure of spinal cord function in CKCSs with syringomyelia, compared with results of EMG or TMMEP assessment. Measurement of SEP amplitude may have use as an objective assessment of the evolution and treatment of this disease. Read the details here.
4March 2011: UK researchers find that the development of syringomyelia is accompanied by alterations in cerebrospinal fluid composition. Read their summary here.
4
"Older dogs scanned have highlighted that SM can be late onset and/or progressive. Several dogs were selected because they already had previously scanned clear but had subsequently developed SM even after the age of 4 years. Such valuable additional information allows the researchers to investigate factors which might influence why some syrinxes progress rapidly and others don’t. Analysis of litters produced using the interim breeding guidelines revealed that higher numbers of dogs which were SM-clear over five years were produced if a parent was also clear of SM over 5 years.
"Donations from RF continue to fund MRIs. Priority is given to male dogs over 6 years, particularly if they have already had a SM-clear scan, but we are also interested in stud dogs of 5 years of age and bitches that have had a scan over 4 years of age or unknown MRI status over 8 years of age and asymptomatic. However, all requests made for Rupert's Fund are considered on an individual basis, and no one should be deterred in applying if they can justify how it helps the breed."
4January 2011: Chiari-like malformation has been re-defined. On the website of syringomyelia researcher Dr. Clare Rusbridge, CM now is defined as "a condition characterized by a mismatch in size between the brain (too big) and the skull (too small). There is not enough room for the brain and the back part (cerebellum and medulla) is pushed out the foramen magnum." The foramen magnum is a hole in the back of the skull -- in the occipital bone -- leading to the spinal cord. Dr. Rusbridge goes on to explain that the cavalier appears to have a brain more appropriate for a bigger dog. Go here for more discussion.
4January 2011: UK researchers find distribution of SM along entire spinal cord of cavaliers; syrinx size positively correlated with age. In MRI studies of 49 cavaliers, reported in 2011 in the Veterinary Journal, Dr. Clare Rusbridge and others found that "Syrinx formation was present in the C1–C4 region and in other parts of the spinal cord. The maximal dorsoventral syrinx size can occur in any region of the spinal cord." Seventy-six per cent of CKCS with a cranial cervical syrinx also had a syrinx in more caudal spinal cord regions.
They concluded that, "MRI restricted to the cervical region may underestimate the extent of SM and the severity of the disease process in the majority of dogs." Therefore, so-called "mini-MRI-scans" of only the cervical region, such as those scans for breeding protocol purposes, may not necessarily locate all syrinx which an SM-affected cavalier may have. They also found that total syrinx size positively correlated with the age of the dog.
4October 2010: Long Island Veterinary Specialists has started "The Canine Chiari Institute", with the mission "To improve the lives of dogs afflicted with Chiari-like Malformation and related disorders through research and continuing education." Its website is under construction, but parts of it are operative.
4October 2010: Current results of following the SM Breeding Protocol. In an interim report of the statistical results of 393 cavalier offspring of MRI-scanned breeding stock, Dr. Clare Rusbridge stated that:
• Matings of Code A CKCS to Code A CKCS have
produced 75.9% offspring with no SM.
• Matings of Code A CKCS to either Code
D, E, or F CKCS have produced 41.9% offspring with no SM.
• Matings of Code A CKCS to unscanned CKCS
have produced 50.0% offspring with no SM.
• Matings of Code D CKCS to Code D, E, or F CKCS have produced no
offspring free of SM
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 additional 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.
4
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.
42004 to 2009 Research: Go to SM Page 2.
Syringomyelia Seminars
4Upcoming: May 26, 2013, "Chiari and syrlngomyelia in toy dogs, latest developments and projects" by Dr Paul Mandigers. Details here.
4Companion Cavalier Club SM seminar by Dr. Clare Rusbridge, November 18, 2012.
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. Speakers were Clare Rusbridge, Dominic Marino, Graham Flint, Guy Rouleau, and Sarah Blott. Obtain compact discs of all five talks and the hour long Q&A session with leading experts on syringomyelia and the Chiari-like malformation in cavaliers, for a contribution to support CKCS genome research at http://www.cafepress.com/cavaliertalk/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.
Related Links
SM Breeding Protocol
Board Certified Veterinary Neurologists
MRI Screening Protocol
Estimated Breeding Values
Cerebellar Infarcts
Primary Secretory Otitis Media (PSOM)
Questions for Cavalier Breeders
Canine Health Testing Clinics
Canine Chiari & Syringomyelia Trust
Dr. Clare Rusbridge:
Dr.
Rusbridge's Comprehensive Website
Rusbridge/Knowler 2010 Research into CM Report
Dr. Rusbridge's Syringomyelia News Winter 2007 Research Update
Dr. Rusbridge's Syringomyelia News Autumn 2007 Research Update
Dr. Rusbridge's Syringomyelia News 2007 Research Update
Dr. Clare Rusbridge video DVD "Syringomyelia Seminar", contact penny.knowler@ntlworld.com
A website devoted to syringomyelia in Cavaliers is Karlin Lillington's SM.CavalierTalk.com
Margaret Carter's "About SM" webpage
Two SM support email groups for owners of dogs with SM are
Yahoo! Group:
Arnold Chiari Dogs
and
Yahoo! Group:
CKCS SM-support
Two SM email discussion groups are
Yahoo! Group: CKCS-SM
and Karlin Lillington's
CavalierTalk: SM
and MVD Cavaliers Forum.
A website and a book about a Cavalier diagnosed with syringomyelia is at For the love of Ollie.
UK Cavalier Club's List of MRI Scanned USA Cavalier Breeding Stock
Cavalier Owners' Blogs:
All about Minnie
(Moo)
Ella's
Battle With Syringomyelia
Riley's Beating
Syringomyelia
Abbey our
CKCS and her family's Syringomyelia Journey
Lucy Magic Sky
Brussels Griffon Owner's Blog:
Friends of Lola
Webpages from Laura Lang's
CKCS Info Center website,
showing additional MRIs
and x-rays of SM-affected or CM Cavaliers:
MRI image primer
MRI
images of Cavaliers diagnosed with and without the malformation and SM
For answers to frequently asked questions about MRIs and what to expect if your dog is to undergo one, see PetsDx - Pet Owners Frequently Asked Questions
YouTube videos of cavaliers with SM
SM in Other Breeds
Other breeds known to be affected by Chiari-like malformation and syringomyelia include the Affenpinscher, Bichon Frisé, Boston terrier, Brussels Griffon (Griffon Bruxellois), bull terrier, Chihuahua, French bulldog, Havanese, King Charles spaniel (the English toy spaniel), Maltese terrier, miniature dachshunds, miniature and toy poodles, Papillon, Pomeranian, Pugs, Shih Tzu, Staffordshire bull terrier, and the Yorkshire terrier. Click on their hyperlinked names to link to Internet articles about CM and SM in those breeds.
