Canine degenerative myelopathy (also known as chronic degenerative radiculomyelopathy) otherwise known as DM or CDRM is a progressive disease of the spinal cord of unknown origin in older dogs. This dog disease has an insidious onset typically between 7 and 14 years of age. It begins with a loss of coordination in the hind limbs. It eventually causes weakness and then leads to paralysis in the back legs. With this dog disease, the myelin sheaths around spinal neurons start to slowly disintegrate. As these protective tissues deteriorate and the underlying nerve fibers (axons) degenerate, the communication pathways between the brain and spinal cord become disrupted.
DM is thought to be an immune-mediated, neurodegenerative disease similar to multiple sclerosis in people, although other possible causes have been suggested. There is no known pattern of inheritance with this disorder, but because it shows up primarily in purebred dogs of certain breeds, a genetic component is suspected.
Clinical signs appear gradually and worsen with time. It can take months to years for full pelvic paralysis to develop. While there currently is no cure for this condition, early recognition of clinical signs, prompt diagnosis and timely treatment can help delay its advancement. If you notice signs of degenerative myelopathy, please take your dog to a veterinarian as soon as possible.
The mutated gene responsible for DM has been found present in 43 breeds including German Shepherds, Boxers, Chesapeake Bay Retrievers, Rhodesian Ridgebacks, and both breeds of Welsh Corgis. German Shepherd Myelopathy is considered to be unique to the breed. The disease is chronic and progressive in the German Shepherd breed, and resulting in paralysis. German Shepherd Dog Myelopathy (aka GSDM) involves profound and complete sensory loss, which is not the case in amyotrophic lateral sclerosis, in which sensory loss is not found.
Symptoms of Degenerative Myelopathy
Degenerative myelopathy initially affects the back legs and causes muscle weakness and loss, and lack of coordination. These cause a staggering affect that may appear to be arthritis. The dog may drag one or both rear paws when it walks. This dragging can cause the nails of one foot to be worn down. The condition may lead to extensive paralysis of the back legs.
As the disease progresses, the animal may display symptoms such as incontinence and has considerable difficulties with both balance and walking. If allowed to progress, the animal will show front limb involvement and extensive muscle atrophy. Eventually cranial nerve or respiratory muscle involvement necessitates euthanasia.
DM causes insidious and progressive lack of muscle coordination, called ataxia. The hind limbs usually are affected first by weakness and slight or incomplete paralysis (paresis).
Owners should look out for some or all of the following symptoms on affected dogs:
- Dog dragging the rear paws and knuckling on the rear toes
- Sores on the tops of the paws
- Signs of wearing on the toenails.
- Odd gait
- Difficulty jumping, running, rising or walking
- Balance difficulties
- Muscle atrophy on the dog’s hindquarters from disuse
- Paralysis of the rear legs
- Possible front limb paralysis
Progression of the disease is generally slow but highly variable. The animal could be crippled within a few months, or may survive up to three years or more.
Many owners mistakenly assume that their older dog is developing arthritis, when in reality canine DM is the culprit. Affected dogs usually become incontinent (both urinary and fecal) very late in the course of the disease, although they are not painful and seem systemically normal. In fact, one of the key clinical features of canine degenerative myelopathy is the absence of any localizable spinal pain.
If your dog is diagnosed with canine DM, talk with your veterinarian about available treatment options. You may also want to ask for referral to a veterinary specialist who has extensive experience with managing this disease. Our mobility harness was originally designed with CDRM in mind and has been an invaluable aid to get the dog mobile.
Known causes of spinal cord dysfunction should be excluded before accepting the diagnosis of degenerative myelopathy; disc disease (protrusions) or spinal cord tumors can cause compression of the spinal cord with similar signs to degenerative myelopathy.
Degenerative myelopathy is a non-reversible, progressive disease that cannot be cured. There are no treatments that have been clearly shown to stop or slow progression of DM.
Exercise has been recommended to maintain the dog’s ability to walk. Physiotherapy may prolong the length of time that the dog remains mobile and increase survival time. Canine hydrotherapy (swimming) may also be more useful than walking. Use of the Quincys harness allows the handler the ability to support the dog’s hind legs while exercising or going up and down stairs. Following the Quincys harness, a 2-wheel cart, or ‘dog wheelchair’ will allow the dog to remain active and maintain its quality of life once signs of weakness or paralysis of the hind limbs is detected.
Dogs at Increased Risk
Dogs degenerative myelopathy is diagnosed most often in aging German Shepherds. Large, older purebred dogs of other breeds are occasionally affected, including the Pembroke and Cardigan Welsh Corgi, Standard Poodle, Rhodesian Ridgeback, Collie, Boxer, Chesapeake Bay Retriever and Irish Setter. The mean age of affected dogs is 9 years. Males and females are equally affected. Younger dogs also can be affected, but this is uncommon.
The following information is to help you understand various ailments that your dog can suffer from and is not intended to replace seeing your vet on a regular basis. If you think your dog may have a problem, I recommend that you see your veterinarian immediately. And remember, please do not give any medication or buy online without first talking to your veterinarian.