Current breeding protocol on syringomyelia:
Many neurologists now describe SM as a "major" breed issue and even the most reserved see it as a very serious issue (for example, the Tufts University veterinary professors who worked on the ACKCS breed health survey report issued last year described the incidence of 4% (all self-reported cases; a quarter of respondents however did not answer questions on SM) as deeply worrying and an extremely high incidence in a breed. You can download the survey here:
Some interesting SM-related features of the survey:
The SM reports --at 4% positively diagnosed and 8.5% suspected of having SM, out of the 566 cavaliers assessed -- will be considered very low in comparison to the various research projects in the UK and US/Canada, currently reporting at least 50% affected, and higher than 70% in some samples.
However, the authors state in the report on page 186:
If anything even remotely close to 50% is the case in the breed, then the incidence is really shocking and I think, must become a major issue for the breed clubs themselves to address directly."Nearly 4% of CKCSs were diagnosed with syringomyelia which is considered extremely high compared with other dog breeds."
The table information is interesting. Apparently 8.5% of the 566 cavaliers in the survey are "believed" to have SM (including the 4% with a definite diagnosis), but a very large 26% of the dogs weren't able to be assessed on that question -- ie the owners did not respond to the question. That's a lot of dogs in the sample for which there's no reply.
39.1% of those believed to have SM were showing signs by age 2, and another 26.1% between age 3 and 4. However, 43.5% weren't diagnosed until between the ages of 4-6, indicating in retrospect, people had seen signs of SM early on, without knowing what it was.
Many neurologists now suggest all breeders should at the very least, try to MRI stud dogs as the studs get widely used (and hence spread their genes more widely), and follow this breeding protocol until something more definitive can (hopefully) be produced, such as a genetic test. This is probably many years in the future though the CKCS genome scan is now underway in Canada, with an international team working on the project.
If you are looking for a cavalier, consider asking the breeder of s/he MRIs the breeding stock and follows these guidelines for breeding. The more people who ask, the more it will place pressure for this to become routine, at least for studs. If buyers are asking, then breeders will ask that the studs be MRId too. Breeders need to see there is value in MRIing and that buyers will give their support to the breeders who do this. By asking, YOU have a say in influencing the future health of this wonderful breed. There are many committed and caring breeders trying to keep this breed as healthy as possible -- let's make sure they know this matters to the rest of us.