Our 12 year old Collie has been diagnosed with degenerative myelopathy. We started noticing a weakness in his hind legs several months ago and thought it was arthritis. However, after a full examination, we were told he does not have arthritis and actually has a good range of motion. He was started on azium, but no positive results were seen. On the contrary, he got worse. He could no longer stand up without help. We reduced the dosage to 1 pill every other day, and he seemed to get a little better. Do you know of any other treatments? Can you provide us with the typical outlook for this condition? How fast does it usually progress and what additional symptoms can we expect?
Degenerative Myelopathy (DM) is a degenerative disease of the spinal cord, whose underlying cause is yet unknown. It is thought to be similar to ALS (Lou Gehrig’s disease) in people. Clinical signs of this disease are most typically a slow progression of hind limb weakness and ataxia (“wobbly” or “drunken” gait), and may start in one hind leg and then progress to the other. This disorder is not painful, and often time dogs are very willing and even excited to continue trying to exercise despite their limitations.
Diagnosis of DM is usually based on a combination of breed, age, clinical signs, and an absence of any other cause for hind limb weakness through orthopedic exam and, in many cases, imaging of the spine via MRI. The spinal MRI of a dog with DM will be normal, ruling out other causes of similar clinical signs such as intervertebral disc protrusion (“slipped disc”), spinal malformations, tumors of the spine and/or spinal cord, and infection or inflammatory diseases of the spinal cord. There is a genetic test for DM available through the Orthopedic Foundation of America. This test can tell if a dog is a carrier for the gene for DM, though this does not definitively diagnose the disease, as some carrier dogs will never develop any signs of DM; it is therefore more helpful to rule out the disease.
At this time, there are no effective treatments for DM. There are some anecdotal reports of improvement with a supplement called aminocaproic acid, however this has not been proven through clinical trials. There has been some recent evidence that daily, controlled physiotherapy including walking, range of motion exercise, massage and hydrotherapy may prolong the ability to walk with DM.
DM will typically progress over a period of 6-12 months, with gradual, if not constant decline in ability to walk. Some dogs will appear to experience “plateaus” in which the disease remains static for weeks or months before progressing again. Most dogs have no other clinical signs, however, as the disease progresses; some dogs will experience urinary or fecal incontinence.
If you are interested in trying to get a more definitive diagnosis for your Collie, ask your veterinarian about referral to a neurologist in your area who will be able to help you decide on a diagnostic plan.
Michaela Esteban, DVM, DACVIM (Neurology)