Drs. Gary Johnson and Joan Coates at the Animal Molecular Genetics Laboratory of the University of Missouri and Drs. Claire Wade and Kerstin Lindblad-Toh at the Broad Institute of MIT/Harvard and their colleagues have identified a DNA mutation that is a major risk factor for development of degenerative myelopathy in dogs.

The research project was funded by the AKC Canine Health Foundation, American Boxer Charitable Foundation, Pembroke Welsh Corgi Club of America, Rhodesian Ridgeback Club of the United States, French Bulldog Club of America, and French Bulldog Rescue League.

A DNA test will be available for breeders and pet owners this June or July, along with information about what the test can and cannot tell them. The test clearly identifies dogs that are clear (have 2 normal copies of the gene), those who are carriers (have one normal copy of the gene and one mutated copy of the gene), and those who are at much higher risk for developing DM (have 2 mutated copies of the gene). However, having two mutated copies of the gene does not necessarily result in disease.

"This will be the first well-documented test available that will help diagnose suspect degenerative myelopathy cases ante-mortem," said Patricia Luttgen, DVM, MS, of the Neurological Center for Animals in Lakewood, Colo. "In the past, only post-mortem diagnosis was confirmatory."

Dogs that have clinical signs or a presumptive diagnosis of DM have tested as genetically affected. A relatively high percentage of dogs in several breeds (including Boxers, Pembroke Welsh Corgis, Chesapeake Bay Retrievers and Rhodesian Ridgebacks) have the predisposing mutation.

It is important to note that there are a large number of dogs that have tested as genetically affected, but are reported as clinically normal by their owners. It may be that many of these dogs will develop clinical signs as they get older or that the mutation will never manifest in these dogs. Research is still needed to determine the frequency of the mutation in breeds known to have DM (German Shepherd Dogs, Rhodesian Ridgebacks, Pembroke and Cardigan Welsh Corgis, Boxers, Chesapeake Bay Retrievers).

In the future, we may identify other risk factors in those dogs that have tested as genetically affected. Wise use of this test can reduce the incidence of dogs at risk for DM in the long-term, particularly if other low frequency risk factors are identified that can more easily be reduced.

It is likely to take many generations to reduce the frequency of this disease in breeds with higher frequency of the mutation. By contributing blood samples for testing this mutation, owners will facilitate further study of the disease and the genetic risk factors underlying it.