Understanding the DNA Test for Degenerative Myelopathy Begrijp de Degenerative Myelopathy in het Nederlands DM – Degenerative Myelopathy – The DM test is available for any breed, and is specifically recommended for Chesapeake Bay Retrievers, Rhodesian Ridgebacks, Boxers, Standard Poodles, German Shepherds, Cardigan Welsh Corgis, and Pembroke Welsh Corgis. For information on DM testing other breeds, please click on the link below T he certificate is extended by the OFA (orthopedic foundation for animals) only when a dog is NOT AT RISK. When a dog is tested AT RISK, a letter is send to the owner of the dog. It is my objective to exclude any future breeding to a dog who is 'at risk' and to submit the certificate hereby shown below to potential buyers. Thus far 7 Kerschberger dogs were tested, 1 AT RISK which dog was taken out of the breeding program. (Stella vom Trompetersprung) Click the images below to see the certificates of which dogs are approved for breeding.    _small.jpg)   Normal (N/N)This dog is homozygous N/N, with two normal copies of the gene. In the seven breeds studied at the University of Missouri in depth so far, dogs with test results of N/N (Normal) have never been confirmed to have DM. This dog can only transmit the normal gene to its offspring, and it is unlikely that this dog or its offspring will ever develop DM. Carrier (A/N)This dog is heterozygous A/N, with one mutated copy of the gene and one normal copy of the gene, and is classified as a carrier. In the seven breeds studied at the University of Missouri in depth so far, dogs with test results of A/N have never been confirmed to have DM. While it is highly unlikely this dog will ever develop DM, this dog can transmit either the normal gene or the mutated gene to its offspring. At-Risk (A/A)This dog is homozygous A/A, with two mutated copies of the gene, and is at risk for developing Degenerative Myelopathy (DM). The research has shown that all dogs in the research study with confirmed DM have had A/A DNA test results, however, not all dogs testing as A/A have shown clinical signs of DM. DM is typically a late onset disease, and dogs testing as A/A that are clinically normal may still begin to show signs of the disease as they age. Some dogs testing A/A did not begin to show clinical signs of DM until they were 15 years of age. Research is ongoing to estimate what percentage of dogs testing as A/A will develop DM within their lifespan. At this point, the mutation can only be interpreted as being at risk of developing DM within the animal’s life. For dogs showing clinical signs with a presumptive diagnosis of DM, affected (A/A) test results can be used as an additional tool to aid in the diagnosis of DM. Dogs testing At-Risk (A/A) can only pass the mutated gene on to their offspring. EquivocalAn Equivocal test result indicates that the test results were inconclusive. This is typically the result of poor sample collection. When the test yields an equivocal result, a second punch will be taken from the FTA card and the test rerun. If the second test is still equivocal, the owner will be contacted and asked to submit a new sample. 
By: Joan R. Coates, DVM, MS, Diplomate ACVIM-NeurologyWe have discovered a gene which is a major risk factor for degenerative myelopathy (DM). In that gene, the DNA occurs in two possible forms (or alleles). The "G" allele is the predominant form in dog breeds in which DM seldom or never occurs; you can think of it as the "Good" allele. The "A" allele is more frequent in dog breeds for which DM is a common problem; you can think of it as the "Affected" allele. Summary: "A" allele is associated with DM; "G" allele is not associated with DM. Since an individual dog inherits two alleles (one from the sire and one from the dam) there are three possible test results: two "A" alleles; one "A" and one "G" allele; and, two "G" alleles. Summary: Test results can be A/A, A/G, or G/G. In the five breeds we studied so far (Boxer, Chesapeake Bay Retriever, German Shepherd Dog, Pembroke Welsh Corgi, and Rhodesian Ridgeback), dogs with test results of A/G and G/G have never been confirmed to have DM. Essentially all dogs with DM have the A/A test result. Nonetheless, many of the dogs with an A/A test result have not shown symptoms of DM. Dogs with DM can begin showing signs of disease at 8 years of age, but some do not show symptoms until they are as old as 15 years of age. Thus, some of the dogs who have tested A/A and are now normal may still develop signs of DM as they age. We have, however, found a few 15-year-old dogs that tested A/A and are not showing the clinical symptoms of DM. Unfortunately, at this point we do not have a good estimate of what percent of the dogs with the A/A test result will develop DM within their life span. Summary: Dogs that test A/G or G/G are very unlikely to develop DM. Dogs that test A/A are much more likely to develop DM. Our research will now focus on how many A/A dogs can survive to old age without developing DM and why. The "A" allele is very common in some breeds. In these breeds, an overly aggressive breeding program to eliminate the dogs testing A/A or A/G might be devastating to the breed as a whole because it would eliminate a large fraction of the high quality dogs that would otherwise contribute desirable qualities to the breed. Nonetheless, DM should be taken seriously. It is a fatal disease with devastating consequences for the dogs and a very unpleasant experience for the owners who care for them. Thus, a realistic approach when considering which dogs to select for breeding would be to consider dogs with the A/A or A/G test result to have a fault, just as a poor top-line or imperfect gait would be considered faults. Dogs that test A/A should be considered to have a worse fault than those that test A/G. Dog breeders could then continue to do what conscientious breeders have always done: make their selections for breeding stock in light of all of the dogs’ good points and all of the dogs’ faults. Using this approach over many generations should substantially reduce the prevalence of DM while continuing to maintain or improve those qualities that have contributed to the various dog breeds. Summary: We recommend that dog breeders take into consideration the DM test results as they plan their breeding programs; however, they should not over-emphasize this test result. Instead, the test result is one factor among many in a balanced breeding program. Joan R. Coates, DVM, MS, Diplomate ACVIM-Neurology Associate Professor Veterinary Neurology/Neurosurgery Department of Veterinary Medicine and Surgery 900 E. Campus Dr., VMTH-Clydesdale Hall College of Veterinary Medicine University of Missouri Columbia, MO 65211
Phone: 573.882.7821 FAX: 573.884.5444 coatesj@missouri.edu For more information on DM, please visit the University of Missouri website
http://www.caninegeneticdiseases.net/DM/ancmntDM.htm
Click here for more information on DM for other breeds A free DNA test for DM is available for some dogs. Click here for details Explanation of DM DNA Test Results Breeder Guidelines for dogs who test DM Carrier (N/A) or DM At Risk (A/A) DM Test Result Statistics
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