What is degenerative myelopathy (DM)?
DM, sometimes called chronic degenerative radiculomyelopathy, is an autoimmune neurodegenerative disease of older dogs. It attacks the myelin, the “insulation” on the nerves.
How do I know if my dog has DM?
Dogs with DM may exhibit progressive weakness and lack of coordination in the hind limbs. DM tends to be underdiagnosed in dogs, so ruling-out other potential causes of its symptoms is important. Diagnosis can be confirmed with a DNA test.
What does having DM mean for my dog?
Unfortunately, DM ultimately advances to paralysis. Euthanasia is required once the disease begins to impact breathing. However caring for a dog with DM, particularly a larger dog like an Aussie, can be physically demanding for the caretakers and many opt for euthanasia when the burden becomes difficult to manage physically and/or emotionally.
How common is DM in Aussies?
It is very rare. However, it is important to keep in mind that breeders should approach all chronic autoimmune disease as a single health concern; different types of autoimmune disease frequently occur in affected families.
Is DM inherited?
Yes. All autoimmune diseases are genetically predisposed: The dog must have the genes to get the disease, but not every dog with the genes will become ill.
Is there a DNA test?
Yes, It identifies a recessive risk-factor. Dogs with one copy of this mutation will remain healthy but have the potential to produce affected offspring. Those with two copies are at risk but they may or may not develop disease. Other factors, probably both environmental and genetic, determine whether a specific dog with two copies will become affected. As of this writing (2019) ASHGI has genetic status on 384 dogs. 4% have two mutations and 14% have a single mutation. Because this disease is so rare there is no point in testing every breeding dog. Healthy relatives of a dog diagnosed with DM which are or will be used for breeding should be tested to determine their status. Carriers and healthy “at risk” dogs should be bred to clear-tested mates.
What does DM mean for my breeding program.
If a dog is clinically diagnosed with DM it should be withheld from further breeding and if it is male and semen stored, that semen should be discarded. Breeders should approach each autoimmune disease as part of an overall health and breeding issue because different autoimmune diseases frequently occur in an affected family. See Autoimmune Disease & Breeding.