Researchers from the University of Bristol have published the results of a study which has identified risk factors for syringomyelia (SM) and which could help breeders select away from characteristics which predispose dogs to the disease.

Syringomyelia, which more commonly affects toy breeds such as the Cavalier King Charles Spaniel and the Chihuahua, causes fluid-filled cavities in the spinal cord. In these toy breeds, SM is usually secondary to a specific malformation of the skull called Chiari-like Malformation (CM).

The research looked at the relationship between head shape and the incidence of  CM/SM. Dogs were measured in several countries using a standardised "bony landmark" measuring system and photos analysed by researchers.

The researchers found two significant risk factors associated with CM/SM in the skull shape of the CKCS: brachycephaly (the broadness of the top of skull relative to its length) and the distribution of doming of the skull. The study suggests that brachycephaly, with resulting doming towards the front of the head, is associated with CM/SM.

Thomas Mitchell, the undergraduate student who conducted the study under the supervision of Dr Clare Rusbridge, said: "Dog breeders are very experienced at selecting for a certain conformation or appearance in dogs. Our findings may allow breeders to select away from the condition over fewer generations by choosing appropriate matings and offspring to continue breeding programmes. The identification of an appearance that might protect against developing the disease is a significant step forward in tackling this painful condition.

"The study also provides guidance to breed clubs, breeders and judges that have a responsibility to avoid obvious conditions or exaggerations which would be harmful in any way to the health, welfare or soundness of the breed.  It will also provide vets with verified advice to provide to breeders outside the show ring and to occasional hobbyists."

The study has been published online in the journal Canine Genetics and Epidemiology, and a video animation which shows the differences in head shape is available on YouTube.

The work was funded by a grant from the Kennel Club Charitable Trust and the Companion Cavalier Club provided a grant for the publication of the research.

Reference

• Syringomyelia: determining risk and protective factors in the conformation of the Cavalier King Charles Spaniel dog, Thomas J Mitchell, Susan P Knowler, Henny van den Berg, Jane Sykes and Clare Rusbridge, Canine Genetics and Epidemiology 2014, 29 July 2014.

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