Cavalier Health

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OVC Syringomyelia Study, Guelph, ON – Dr. Poma and Dr. Wolfe
The OVC Syringomyelia Study has just recently ended and a final report has not yet been completed. However, a brief synopsis of the study, OVC Syringomyelia Study, courtesy of Karen Kennedy, explains the goal and testing methods used in the study.

The Syringomyelia Study Project at the Ontario Veterinary College has been successfully completed with a total of 50 Cavaliers MRI scanned. Dr. Poma was instrumental in writing the proposal for our Study to the Pet Trust committee at OVC in Guelph to enable our members to have an affordable MRI of full spinal scans.

Thank you Dr. Poma, Dr. Nykamp, and Dr. Wolfe for your commitment, and hard work to this very important research of Chairi-like malformation and Syringomyelia.

Blood from each Cavalier was sent to Sainte Justine Hospital at the University of Montreal for DNA for the Genome Study. Results were also sent to Penny Knowler and Dr. Sarah Blott in the UK.

Thank you to all participants' and their wonderful Cavaliers for contributing to this important study project. We look forward to a completed report from all the information collected by Dr. Poma and Dr. Wolfe in the near future.

Current Approach to Syringomyelia in the Netherlands

Paul J.J. Mandigers, DVM, MVM, PhD, DECVN; DRNVA-Internal Medicine, Utrecht University



Key Points

Both SM and MVD are known problems within the Dutch CKCS population that have reduced life expectancy from 13-15 years (for dogs of similar weight) to 8-10 years Because SM has only been addressed on a consulting basis (eg when people have brought in an affected dog) it is impossible to make estimates of prevalence. However, SM is expected to become more prevalent because asymptomatic cavaliers have been allowed to breed. Due to a private initiative from a Dutch breeder that started in 2002, 196 CKCS have been MRI-screened for SM. The point of screening is to identify the best possible breeding animals. Of these: 30% were graded A/B; 14% were C; 39% D, 13% E and 4% F, using the Rusbridge grading scheme. Overall 56% had SM. Blood samples were taken for all dogs for DNA research. In a two year period, 2004-2006, Dutch breeders have increased the number of dogs scanning as A/B from 10% to about 25% by concentrating on screening relatives of clear dogs rather than random dogs

Early Observations

  • 14 Breeders demonstrating best use of their clear dogs
  • Coping with large number of affected dogs
  • Initially A x D crosses predominated (not enough As)
  • Now A x A mating is an option
  • Up to 4 generations “SM clear”
  • SM Clear dogs related to other SM clear dogs
  • No SM affected dogs from A x A crosses

Summary of Talk (Clare Rusbridge read this paper as Paul Mandigers could not attend)

Of a population of 74 screened for one project, 75 per cent had SM. There is a wide range of affectedness -- not all cases are painful (about 30%). The worst pain is experienced when the syrinxes are wide, and early onset cases tend to be the worst as well. It is unrealistic to expect to eliminate SM as there are too many affected dogs (similar to the case with MVD) and some dogs with SM are free of clinical signs making it hard to pinpoint dogs with it by breeding age unless MRId. So the goal must be to increase the number of symtom-free CKCS.

Breeders are in a difficult place because they are told, don’t breed from affected dogs. However, individual breeders may not have any clear dogs; and affected dogs may be valuable champions and valuable in other respects eg good hearts. Breeeders also really need a screening test for young dogs, but because the condition is progressive, we don't currently have the ability to pick an ideal age for screening.

The best compromise (and that used by the Dutch breeders in this project) are the breeding guidelines suggested by Clare Rusbridge which allow some affected dogs with other valuable qualities to be bred to clear dogs, and which uses the age of 2.5 yrs to fit with the heart protocol (NB CR noted the age was arbitrary but was intended to fit breeders’ use of the heart protocol). In summary: don’t breed dogs with clinical signs (F dogs); don’t breed dogs with early onset SM (E dogs); breed asymptomatic SM dogs (D) to clear (A/B) dogs; breed at risk (C) dogs with clear (A/B) dogs only.

In the Netherlands, 14 breeders set up the Cavalier Guild for Health and have been screening their dogs since 2000. This is a breeder-led selection of dogs (so no researcher control over which dogs are scanned), and dogs are selected in order to identify the best animals for breeding and with the aim of producing pain-free dogs. In 2004, 70 dogs were scanned showing a 70% incidence of SM and only 10% were clear A/B dogs. Scanning showed that clear dogs tended to be closely related to other clear dogs while affected dogs were closely related to other affected dogs.

By concentrating on screening relatives of clear dogs and screening early -- at 7-18 months to identify good candidate offspring to know which were worth running on -- by 2006, 196 different dogs had been screened and about 25% were clear A/B dogs. All sires and dams are screened; puppies are homed with a one year health guarantee. This breeding programme demonstrates that significant successes can be achieved in only a relatively short period period.

Breeders were coping with large numbers of affected dogs -- initially they had very few A dogs and had to do lots of AxD matings. Now, AxA is an option for them. They have had up to four generations “SM clear” (A/B offspring) and no AxA mating has yet produced an affected offspring. SM clear dogs are definitely related to other SM clear dogs and those are the lines the breeders are focusing on. He hopes to do follow up screenings with dogs to see how they progress.

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