The onset of DM is usually in a dog's senior years. Affected dogs first begin by exhibiting muscle wasting, proprioceptive deficits, and knuckling of the hind feet. Though the condition is not painful, affected dogs will eventually require assistance walking. As the condition progresses, it moves up the spinal cord and the dog's neurologic deficits mirror the progress, losing fecal and urinary continence and eventually involving the front legs and the brainstem.

The wellbeing of dogs suffering with degenerative myelopathy should be monitored closely as the disease progresses. Euthanasia is usually elected on welfare grounds when clinical signs become severe.

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

Please note the DM mutation has only been associated with disease signs in some breeds, and this should be considered when making breeding decisions. This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to develop. A carrier dog with one copy of the DM mutation can be safely bred with a clear dog with no copies of the DM mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the DM mutation. A dog with two copies of the DM mutation can be safely bred with a clear dog. The resulting puppies will be all carriers with one copy of the DM mutation. Puppies in litters which are expected to contain carriers should be tested prior to breeding. Please note: It is possible that disease signs similar to the ones caused by the DM mutation could develop due to a different genetic or clinical cause.