January 2004
A research update

By Clare Rusbridge and Penny Knowler
Stone Lion Veterinary Centre, 41 High Street, Wimbledon, London, SW19 5AU (CR) (SPK)

The search for the gene(s) has entered the first phase and a UK and North America DNA collection scheme has started for CKCS with syringomyelia, mitral valve disease and/or epilepsy; their relatives; and normal CKCS. Information on the DNA collection scheme can be obtained from Funding for part of this has been generously provided by the pharmaceutical firm Boehringer Ingelheim as part of the Healthy Heart partnership and in the UK the samples are being stored by The DNA Archive (Archive Coordinator - Wendy Hallows ). Ultimately it is hoped the DNA and the pedigree database can be used to find the causal genes for both diseases.

A gene is found by comparing the DNA of affected dogs, their unaffected relatives and unaffected unrelated dogs. So far collection has focused on obtaining blood from the extended families of dogs affected by syringomyelia. It is also important to have a large amount of DNA from known sources i.e. popular sires and dams. Consequently several top breeders have arranged for their champion stud dogs and brood bitches and extended families to contribute. This will allow the development of a framework to compare to affected dogs. We are hoping that other breeders will follow suit.

We hope to find a way to enable other European CKCS owners to contribute samples towards the DNA archive in the near future.

Answers to common questions
Can we not just breed away from the problem?

Unfortunately syringomyelia is very widespread in CKCS lines and the number of potential carriers is huge so that breeding program based on avoiding certain dogs is not feasible or advisable as this will further narrow an already small gene pool resulting an increased likelihood of other inherited diseases. For example, it appears that selecting CKCS for good hearts is making syringomyelia more prevalent. To preserve the breed health we need to keep the gene pool as large as possible. Dogs that carry syringomyelia or heart disease will have "good genes" for other inherited factors and we do not want to lose this valuable genetic material. A blood test for the gene(s) would be ideal because it allows carriers or even affected dogs to breed with non carriers (who may carry the tendency for a different disease).

Why can you not tell us the pedigree names of dogs with this condition?

There are several reasons but the most important is that pedigree information was given confidentially by concerned owners and breeders with the aim of gaining valuable information on the inheritance of the condition and ultimately benefiting the whole breed. To break this confidence would be unprofessional and unethical. Additionally there are thousands of dogs that could potentially carry the condition, as every dog related to an affected dog is implicated. Having such a huge list is not going to make it easier to select a mate. If there are minority of dogs not on the list they will be overused leading to a narrower gene pool and other diseases. Finally, we do not have an exhaustive list of every affected dog as not every breeder is open about the problem. Having a list would imply that those not on it are safe which may not be the case.

Can you not just tell us the names of the important common ancestors G, Z, C, D, M and S indicated in the recent scientific papers?

No, for the reasons given above but in addition all modern CKCS will have some or all of these ancestors therefore the information is not practical.

If you are a breeder that has produced or wants to avoid affected dogs what can you do?

Unfortunately until there is a gene test for the condition then advice is very limited as follows:

Affected case Identified by MRI or suspected on basis of clinical signs (scratching at shoulder area when walking on leash or when excited).

  • Not to be used for breeding.
Unaffected known carrier (sire, dam or offspring of an affected case).
If mated with same can produce affected offspring.
  • Only use very sparingly - i.e. retaining maximum possible variation in the gene pool but not saturating it.
  • Mate only with unrelated dogs who have had no extended family history of the disorder
  • Ideally delay breeding until the dog is three years old - most cases of syringomyelia will be displaying signs of disease by 3 years.
Unaffected dog (it is likely that all modern CKCS will be carrier one or more of the genes).
  • Don't use closely related dogs; even from your own known breeding line.
  • Maintain good communication between any breeding partner
  • Keep track of offspring as time of onset of disease can vary.
  • Ideally delay breeding until the dog is three years old - most cases of syringomyelia will be displaying signs of disease by 3 years.
Obviously the recommendations for avoiding heart disease should also be taken into account.

Is there any evidence for the influence of any environmental factors such vaccinations or diet?

None as yet.

Is there any other way than MRI (expensive) to diagnose the condition?

The disease can be highly suspected when there are signs such as shoulder/neck scratching in the absence of skin disease and especially when walking on the leash or when excited. It is also likely if a young dog presents with scoliosis (spinal curvature) and is a possibility in any CKCS with neck pain. However the only way to confirm the diagnosis is with MRI.

When is surgery indicated?

Surgery is advised for dogs with significant pain or that are deteriorating. As this is technically difficult, it is only available at specialist centres. The aim of surgery is to reduce pain and prevent further deterioration. There are two types of surgery performed for this disease 1) foramen magnum decompression where the hypoplastic occipital bone and sometimes the dorsal laminae of the atlas are removed to recreate a foramen magnum and 2) shunting the syrinx. Although surgery is successful in many dogs some may have a recurrence or still show signs of pain/scratching.

My dog is in pain- what treatment can help?

Treatment options are limited. Drugs can help but typically do not resolve the clinical signs. The aim is to reduce the discomfort i.e. the scratching and screaming. Some mild cases are helped by NSAID drugs e.g. daily dose of Metacam© or Rimadyl©. The best response is seen with corticosteroids. However these drugs are associated with side effects such as immunosuppression, weight gait and skin changes and long term mediation with these drugs is not advised. If there is no alternative then use the lowest possible dose to control signs and ideally give on alternate days. Gabapentin (Neurontin) has been successful in some dogs. This is not a licenced medication in dogs but is licenced as a neurogenic pain killer in humans. The dose is 10-20mg/kg 2-3x times daily which for a CKCS typically works out at a dose of 100mg 2-3x daily. Sedation may be seen at high doses. Neurontin can also be given with NSAIDs, steroids or opioid e.g. pethidine tablets at 2-10mg/kg 3-4xdaily or methadone syrup at 0.1-0.5mg/kg 3-4xdaily. The main disadvantage of Neurontin is that it is expensive.

Acupuncture appears to help some dogs.

Will my dog ultimately be paralysed?

Comparatively few dogs with syringomyelia deteriorate to the extent that they have difficulty walking. Severe neurological deficits are more likely if the dog first shows signs before a year of age. For most dogs the pain and discomfort is the most severe sign.

I owned a dog with typical signs before the disease was fully understood. Is there any point in passing this information on if the dog is dead?

Yes. The more information about affected dogs and their relatives we know, the better chance we have of understanding the inheritance. Close family relatives and descendants possess valuable DNA with which to make comparison with. All information remains confidential.

How can I help?

Priority at the moment is collecting quality DNA. We need DNA from as many confirmed cases as possible plus their unaffected relatives. Please volunteer your CKCS or agree to participate in the scheme if you are asked. Blood is the best source of DNA but in the UK this can only be donated surplus to a (any) diagnostic test (see for further details). It costs approximately 10 to sample each dog and monetary contributions towards the research fund are always welcomed.

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The information given in these Research Updates are not necessariy those of the Cavalier King Charles Spaniel Club and are provided for information only
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Material Copyright © 2005 The Cavalier King Charles Spaniel Club
and C Rusbridge