Degenerative Myelopathy (DM) is a progressive neurological disorder that affects the spinal cord of dogs. DM is a recessive disorder; however, symptoms can present themselves even with one copy of the defective gene. If a dog has one copy of DM, they can still develop DM symptoms. However, their chance for developing symptoms is less compared to a dog with two copies of the DM mutation. Genetic testing reveals the susceptibility of dogs developing DM. It is important to note that even though a dog possesses two copies of DM, it does not mean that the dog will develop symptoms of DM. It simply means that the likelihood of the dog developing DM symptoms is much higher than average.
Dogs that have inherited two defective copies of DM will experience a breakdown of the cells responsible for sending and receiving signals from the brain, resulting in neurological symptoms. This breakdown of communication between the body and the brain can have several effects.
The disease often begins with an unsteady gait, and the dog may wobble when they attempt to walk. As the disease progresses, the dog's hind legs will weaken and eventually the dog will not be unable to walk at all. Degenerative Myelopathy moves up the body. If the disease is allowed to progress, the dog will eventually be unable to hold his bladder and will lose normal function in its front legs. Fortunately, there is no direct pain associated with Degenerative Myelopathy. DM generally occurs later in life. It typically begins an average age of about 10 years. However, some dogs may begin experiencing symptoms much earlier.
|At Risk: Dog has two copies of the DM mutation and is at a significantly higher risk of developing DM, The mutation will always be passed on to every offspring. Affectedness varies by breed.
|Heterozygous: Dog carries one copy of the mutation associated with Degenerative Myelopathy. In some breeds, there is a low risk of the dog developing the disorder
|Clear: Dog is negative for mutation associated with Degenerative Myelopathy.
Shelton GD, Johnson GC, O’Brien DP, Katz ML, Pesayco JP, Chang BJ, Mizisin AP, Coates JR. Degenerative myelopathy associated with a missense mutation in the superoxide dismutase 1 (SOD1) gene progresses to peripheral neuropathy in Pembroke Welsh Corgis and Boxers. J Neurol Sci. 2012 Jul 15;318(1-2):55-64. [PubMed: 22542607]
Zeng R, Coates JR, Johnson GC, Hansen L, Awano T, Kolicheski A, Ivansson E, Perloski M, Lindblad-Toh K, O'Brien DP, Guo J, Katz ML, Johnson GS. Breed Distribution of SOD1 Alleles Previously Associated with Canine Degenerative Myelopathy. J Vet Intern Med. 2014 Feb 13. doi: 10.1111/jvim.12317. [PubMed: 24524809]