CM/SM is a neurological condition, (similar to Arnold Chiari syndrome in humans) which has only been recognised and named within the last 15 years.
Syringomyelia is an inherited condition but at present, the mode of inheritance is not known but is thought to be of a complex, polygenetic nature.
A great deal of research is being carried out internationally trying to find the genes responsible, supported by donations from Cavalier breeders and Cavalier Clubs worldwide.
Chiari-like malformation (CM) is characterised by a mismatch in size between the brain and the skull. The opening from the skull to the spine may be partially blocked and may alter the flow of cerebrospinal fluid (CSF) around the spinal cord. As a result, fluid filled cavities called syrinxes can develop within the spinal cord, with the condition being called syringomyelia (SM).
Cavaliers may have a syrinx and never display symptoms. The only accurate way of diagnosing a dog’s condition if it does not have any symptoms is by MRI scan which requires a general anaesthetic. This is an expensive procedure and MRI scanning to screen breeding dogs is not available in all parts of Australia. Where MRI scanning is available, a growing number of breeders now have their dogs scanned for the presence of SM at days organised several times during the year by a specialist neurologist vet.
Dogs should be scanned when mature or before being used for breeding. This gives the breeder information that will assist in planning suitable matings.
CM/SM has been shown to be inherited in the Cavalier King Charles Spaniel and the Griffon Bruxellois and is suspected to be inherited in the King Charles Spaniel. Other breeds reported with the condition include, among others, Maltese, Yorkshire Terriers, Chihuahuas, Papillons, Pomeranians, Affenpinschers, Havanese, Boston Terriers and Staffordshire Bull Terriers.
Although some dogs with a mild CM/SM can seem completely normal, other dogs experience pain and may be unable or unwilling to exercise and may have increased sensitivity to touch especially around the head, neck, shoulders and sternum (breast bone). Severe cases may display a characteristic shoulder, neck and/or head scratching where they ‘air-scratch’ without making contact with the body. Some dogs show neurological signs such as lack of co ordination and weakness.
NB - Scratching at the neck and shoulders and sensitivity in this area are also symptoms of other, more common ailments including ear infections, ear mites, skin conditions and allergies, fleas and other spinal or disc problems which should be fully investigated before assuming the symptoms are those of SM.
For affected dogs, drug treatments are available which may assist in improving the dog’s quality of life.
The complex nature of this condition makes the breeders task a difficult one but recent research in the UK has shown that breeding together dogs free of SM and especially those dogs scanned free of SM at older ages, produces the best results in the next generation and reduces the risks of breeding affected dogs.
MRI scanning to screen for SM in non symptomatic breeding dogs is available in Sydney – for further information contact the booking co-ordinator Janine Gilroy Telephone: 02 4683 3503 or Email.
Dogs which display symptoms need to be referred by their local veterinary practice to a veterinary neurologist specialist for accurate diagnosis and treatment.