New Canine Degenerative Myelopathy Test
Possible Genetic Link to One Progressive Spinal Cord Disease in Dogs
Sep 3, 2008
The Canine Genetic Diseases Network has announced that Dr Gary Johnson of the Animal Molecular Genetics Laboratory and Dr Joan Coates of the Cooperative Neurology Program at the University of Missouri, along with Drs. Claire Wade and Kerstin Lindblad-Toh at the Broad Institute of MIT/Harvard and colleagues identified the genetic mutation linked to the development of canine degenerative myelopathy.
The disease results in hind limb paralysis over time and there is no recognized effective treatment for affected dogs. But DNA tests will help dog breeders in their efforts to reduce the incidence of canine degenerative myelopathy and may eventually lead to a better understanding of the disease.
Understanding Canine Degenerative Myelopathy
This disease, a result of gradual loss of both myelin (the insulation around nerve fibers) and spinal cord nerve fibers which begins in the thoracic spine, causes progressive loss of coordination and weakness in the back legs which eventually leads to the dog being unable to walk. Loss of bowel and bladder control result as well. Unlike spinal cord injuries, this form of spinal paralysis is generally not painful as the nerves which would transmit the pain degenerate.
Until this recent genetic breakthrough, a tentative diagnosis of canine degenerative myelopathy was made by eliminating other possible causes when a dog showed hind limb paralysis. Herniated intervertebral disks, tumors, cysts, stroke or canine vestibular syndrome can all cause similar symptoms and each must be ruled out. An absolute diagnosis of degenerative myelopathy is only possible on post mortem examination.
The New DNA Test for Degenerative Myelopathy
Genetic testing can now be used as one more tool in confirming cases of canine degenerative myelopathy when they develop clinical signs. Dogs who have two of the abnormal genes, one from each parent, are the only ones that have developed the disease in this study so far. At this time some dogs in the study have two mutated genes but have not shown signs of the disease. It is unclear yet whether these dogs will later develop the disease or if there are other factors that must also be present for canine degenerative myelopathy to develop.
This DNA test also helps dog breeders work to eliminate the problem in their bloodlines. By testing dogs before breeding, they can avoid mating two dogs with the affected DNA.
Further Research and Development is Needed
The canine degenerative myelopathy DNA test was developed using breeds that have a strong predisposition to the disease. These breeds are German Shepherd Dogs, Rhodesian Ridgebacks, Cardigan and Pembroke Welsh Corgis, Boxers, Chesapeake Bay Retrievers and Standard Poodles.
Through funding by the AKC Canine Health Foundation, various dog breed clubs and concerned individuals, free DNA testing is available to dogs who have a tentative diagnosis of canine degenerative myelopathy from a veterinary neurologist or their own veterinarian. Other dogs who fit the ongoing research criteria, which can be found at the Canine Genetic Diseases Network website, are eligible for the free DNA tests as well. For dogs that do not meet the criteria, the Orthopedic Foundation for Animals (OFA) provides the genetic tests at a moderate cost.
At this time the finding of a genetic mutation that may be linked to canine degenerative myelopathy only aids in diagnosing the disease and provides dog breeders with another tool for breeding healthy dogs. But it is another step in understanding this devastating disease.
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