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. The 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 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
Dogs at Increased Risk
Oregon Veterinary Specialty Hospital (OVSH) has been serving the Portland and Beaverton area community since 1979. Drs. Steven F. Skinner (Neurology, Neurosurgery) and Robert T. Franklin (Internal medicine.) We welcome referrals from veterinarians all over the Pacific Northwest. Our goal is to help your pet regain health and live a long and happy life.
Oregon Veterinary Specialty Hospital
9339 SW Beaverton Hillsdale Hwy,
Beaverton, OR 97005.