was once a very rare condition that is much more prevalent of late--sometimes called the
scratching disease as dogs who get this often scratch almost uncontrollably in
their neck and shoulder area at times, often not even touching skin. Note
though that only 30-40% of Cavaliers with SM actually scratch however! Here is a short synopsis of
what SM is, written by Clare Rusbridge.
Clare Rusbridge BVMS DipECVN MRCVS
her new website is at
Please check it out for some wonderful information
and the latest on SM!
What is Syringomyelia?
Syringomyelia is a condition whereby fluid filled cavities develop within the
spinal cord. Some refer to SM as "neck scratcher's disease"
because scratching in the air near the neck is a common sign.
Click on picture above to go to MRI
What causes it?
Syringomyelia is a consequence of an obstruction to cerebrospinal fluid (CSF)
flow. In the normal mammal, the CSF around the brain shunts back and forth with
the arterial pulse. If this rapid efflux and influx is obstructed then the
pressure wave is transmitted down the spinal cord distending it immediately
below the blockage. This results in the formation of a cavity or syrinx.
Syringomyelia can occur from any blockage in the subarachnoid space (space
containing CSF around the brain and spinal cord). However, the most common
cause is the cerebellum within the foramen magnum (i.e. the back of the brain
poking though the hole at the back of the skull). The cerebellum is pushed
(herniated) out the skull because there is not enough space since the bone at
the back of the skull (occipital bone) is too small. This condition occurs
in many small breeds but is common in the cavalier King Charles spaniel (CKCS)
(conservative estimates at least 50% of the breed). It is similar to the human
condition Chiari malformation (some vets refer to it as Arnold Chiari syndrome
which is incorrect and confusing as this original description by Arnold was of
syringomyelia associated with spina bifida and this is not the case in the CKCS).
What are the clinical signs of syringomyelia?
By far the most important sign of syringomyelia is pain. This is most commonly
localised to the neck region but may be difficult to define or intermittent.
Owners often report that their dog is worse at night; when first getting up;
during hot or cold temperature extremes; when excited; or related to posture
e.g. preferring to sleep with their head raised. They may seem to be overly
sensitive to touch on one side of the neck / ear / shoulder / sternum. In
addition affected dogs often scratch at one area of the shoulder, ear, neck or
sternum. This is typically one side only, while the dog is moving and sometimes
without making skin contact Some dogs, more commonly younger patients, develop a
scoliosis (twisted spine). Some severe cases may have other neurological
deficits such as fore and hindlimb limb weakness and ataxia (wobbliness). Facial
nerve paralysis and deafness have also been associated with the condition.
What age of dog is affected?
Clinical signs of syringomyelia secondary to occipital hypoplasia are usually
recognized between 6 months and 3 years of age. However, dogs of any age may be
presented and dogs with more severe disease tend to be presented before two
years of age.
Do the signs get worse?
Progression of the disease is very variable. Some dogs have the tendency to
scratch with mild pain only and other neurological signs, such as paresis, never
or very slowly develop. Others can be severely disabled by pain and neurological
deficits within 12 months of the first signs developing. Mild syringomyelia may
also be found as an incidental finding, with no recognised clinical signs, in
the investigation of another neurological disease.
Are there any diseases with similar signs to syringomyelia?
The main diseases to rule out are other causes of neck pain e.g. disc disease
(uncommon in dogs less than two years of age); CNS inflammatory diseases and
other malformations. If scratching or face rubbing is the main sign then skin
disease should be eliminated.
How do I know if my dog has Syringomyelia?
The only way to confirm a diagnosis is by MRI (Magnetic Resonance imaging). This
is essentially a picture of the water content of the body presented in a series
of slices (like a loaf of bread). Nervous tissue, which contains a lot of water,
is not imaged by x-rays but is shown in great detail by MRI. The
syringomyelia can be easily visualised as a pocket of fluid within the spinal
cord. In severe cases the syrinx is so wide that only a thin rim of spinal cord
you decide to have your dog MRId, please download the form below and take it to
Once the neurologist has filled out the form, please return it to Clare
It will be especially important to report the grade of Chiari Malformation if
you submit your MRI here.
If my dog has been
diagnosed with Syringomyelia what are the options?
No one can make the decision for you about what is best for your dog.
Long-term studies of medical management of syringomyelia are not available yet.
The drugs used to treat syringomyelia can be divided into 3 types:
. drugs which reduce CSF production;
Pain in mild cases may be controlled by non steroidal anti- inflammatory drugs.
(NSAIDs) e.g. Rimadyl and Metacam. In more severe cases anticonvulsants,
which have a neuromodulatory effect on hyperexcitable damaged nervous system,
may be useful, for example gabapentin (Neurontin Pfizer; dose rate 10-20mg/kg
BID/TID - these are not licenced for dogs). Oral opioids, e.g. pethidine or
methadone are also an alternative.
Drugs which reduce CSF production
Proton pump inhibitors such as omeprazole (Prilosec; Proctor and Gamble) can
inhibit cerebrospinal fluid formation and therefore may be useful; clinical data
on their use and effectiveness is currently lacking. Carbonic anhydrase
inhibitors such as acetazolamide (Diamox; Lederle laboratories) also decrease
CSF flow and may also be helpful in treating syringomyelia although adverse
effects of abdominal pain, lethargy and weakness may limit long term use
Corticosteroids are very effective in reducing both pain and neurological
deficits although the exact mechanism is not known. It has been suggested that
these drugs reduce CSF pressure however laboratory evidence of this is lacking.
They possibly have a direct effect on pain mediators such as substance P.
Although corticosteroids may be effective in limiting the signs and progression,
most dogs require continuous therapy and subsequently develop the concomitant
side effects of immunosuppression, weight gait and skin changes 1. If there is
no alternative then the lowest possible dose that can control signs is used.
Alternate day therapy is preferred. The author starts with 0.5mg/kg prednisolone
/ methylprednisolone daily.
Surgical management is indicated for dogs with significant pain or with
worsening neurological signs. The aim is to restore CSF dynamics and if this can
be achieved then the syrinx can resolve. The most common procedure for
Chiari like malformation is suboccipital decompression where the hypoplastic
occipital bone and sometimes the cranial dorsal laminae of the atlas are removed
(with or without a durotomy) to decompress the foramen magnum. The success
reported in the small case series varies from no improvement to post operative
resolution of the syrinx. Syringo-subarachnoid shunting has also been described.
In the author's experience surgery is usually successful at significantly
reducing the pain but some dogs may still show signs of discomfort /scratching.
Also in the author's experience signs may recur in a proportion of dogs after
several months/years due to redevelopment of syringomyelia.
One must weigh the risks and benefits of surgery versus
medication versus no intervention. Remember, progressive disease means
that no action may enable further deterioration. When measuring the
surgery's success, measure from current condition to the expected future
condition - what the disease would have progressed to, rather than the current
When to have surgery?
There is more chance of success if the surgery is done early in the course of
the disease before permanent damage has occurred. Surgical management is
indicated for dogs with significant pain or with worsening neurological signs
What are the risks of surgery?
There are major blood vessels in the area and if traumatised the dog could
quickly bleed to death. Although not actually operating on the brain/spinal
cord, it is in close proximity and there is a risk of permanent neurological
injury. In reality complications from surgery seem to be rare.
Can the disease recur?
In the authors' experience signs may recur in a proportion of dogs after several
months/years due to redevelopment of syringomyelia. The newly created
"space" from surgery may fill in with scar tissue. If this
happens, repeat surgery may be indicated; some owner prefer to continue with
medical management e.g. with NSAIDs, gabapentin or corticosteroids.
What post surgery drug treatment would you advise?
Dogs are hospitalised until comfortable enough for morphine-like-drugs to be
discontinued and then discharged on a combination of non steroidal
anti-inflammatory drugs (e.g. Rimadyl) and gabapentin (Neurontin). This is
withdrawn when the dog is comfortable (about 2 weeks in most cases).
DNA collection programme
Our aim is to provide a comprehensive, integrated collection of cavalier King
Charles spaniel DNA for the benefit of the dogs, owners, breeders and to provide
insight into human disease. Surplus blood from a health check would be stored
for future studies on the health of the breed. The current studies include
syringomyelia (SM), mitral valve disease (MVD) and Epilepsy.
Questions & Answers
Why is blood needed?
It is easy to extract DNA from the white blood cells in a blood sample. To do
this the blood must be fresh and prevented from clotting by putting it in an
What will happen to the blood sample from my dog?
The DNA sample being submitted to the researchers will be anonymous once it is
entered into the archive and will be kept strictly confidential. The samples and
clinical data will be made to available to bona fide research groups working on
these conditions and where the projects have been deemed to be ethically sound.
The owner will also retain the right to remove the sample from the archive in
the future if so wished. However, no information regarding tests performed on
the DNA sample will be given back to the owner. It will only be possible to find
out which genes and environmental factors are important by identifying patterns
in large numbers of affected and unaffected animals.
What kinds of dogs are needed to give blood?
All blood from your cavaliers will be valued. The purpose of the study is
to identify a gene through DNA analysis. We are therefore focusing on certain
areas to be most successful in achieving our goal. We need dogs that are .
Normal healthy, especially if over 7years or MRI confirmed normal (no SM)
. Champions that often appear in pedigrees (any age)
. SM Affected -MRI confirmed or showing typical clinical signs
. Parents and siblings of affected dogs
. Offspring of affected dogs - If <3 years of age the blood may be stored in
case signs develop later.
. Mates of an affected dog - is helpful if DNA from offspring is collected later
. MVD affected and their relatives (see SM above)
Remember your blood donation will help keep Cavaliers healthy from inherited
diseases. SM/MVD carriers can have good genes/characteristics that we need
to conserve. The more help we get the speedier will be the result.
Why do I need to provide a pedigree?
Pedigree information about your cavalier is important for our study. The
relationship between affected and non-affected family members can indicate the
way in which a disease can be inherited. Comparisons are made between the
parental genotypes and those of the offspring. Pedigree
analysis is not sufficient in itself to determine if a trait is inherited as a
threshold trait. There are many investigations to be made and that is why you
are asked for as much blood (DNA) as possible. Linkage may be used, which
means DNA from animals that link up affected individuals would be needed.
Bottom line: It is essential that we have DNA from related dogs regardless
of whether their status is known.
Copyright: Clare Rusbridge BVMS DipECVM MRCVS
are links to a few pages of MRI images of various dogs. Each dog's
symptoms (or lack of) will be reported along with the neurologist's diagnosis--no
names will be used unless one wants their dog to be named. Anyone who
wishes to submit an MRI to be shown here is welcome to do so. Clear MRI,
symptoms of dog if any, and diagnosis is needed with the submission.
We are especially interested in having the MRIs of any clear/clear dogs--free of
the malformation and free of SM. Please contact
if you wish to provide an MRI however note that only quality MRIs will be
posted. Central spinal canal must be somewhat visible.
This part Under Construction
very interesting comparison of skull xrays of Cavaliers with and without SM
as compared to their MRIs and a comparison
of Cavalier heads from the 70s to today
(Malformation) Comp Page
of MRIs in order of cerebullar crushing, from almost no CM to severe CM
is a link to an Adobe Acrobat copy of the SM Evaluation Form.
We would like anyone and everyone who has a dog MRId to download this form and
take it to their neurologist. We are especially interested in getting the
amount of CM
(Chiari Malformation) of each dog that is MRId according to the scale on the
We are hoping to improve the consistency of grading of CM in dogs with this
is a link to an excellent website with an article on the significant differences
in back skull development between humans with and without the chiari malformation.
following is a new website which details as much as is presently known about SM
all in one place. Symptoms, treatments, research, etc. A great
resource for anyone interesting in SM, worried their dog has SM, owners of dogs
newly diagnosed with SM and wondering about treatment plans.
For more on this condition
please see the following sites:
is another page explaining several malformations of the skull and their
relationship to SM/SHM. Check out the sections under Chiari Malformations,
Occipital Dysplasia and Hydrocephalus.
you suspect your dog has this, I would suggest you join the SM/Arnold Chiari
support group. You can do so by clicking on the link below and following
the directions to join.
CKCS-SM Discussion List
note that a blood drive is being done for SM. Epilepsy and MVD. The blood
will be DNA scanned in an effort to find some of the genes responsible for these
defects. The blood of both affected and older non-affected dogs is
necessary for this study. More information on how the blood should be
collected and sent and where it is to be sent is available on "the cavalier
club" site linked to above.