Effects of Degenerative Myelopathy – From the Dog’s Point of View
Canine degenerative myelopathy (DM) is an uncommon, progressive degenerative disease that causes hind limb weakness and paralysis and eventually affects the front limbs, as well. The symptoms of DM start gradually, usually in adult dogs over 5 years of age. Early in the course of the disease, affected dogs will start to lose muscle coordination and balance in their rear legs (ataxia). They will develop slight or incomplete hind end paralysis (paraparesis), which will progress to total rear end paralysis (paraplegia), accompanied by varying degrees of urinary and/or fecal incontinence. As the dog loses its ability to stand and use its hind legs, it may develop bed sores and wounds from urine scalding, which can be extremely painful. It usually takes somewhere between 6 and 12 months for full pelvic paralysis to develop in dogs with DM. The front legs will be affected next, starting with lack of coordinated movement (ataxia) and progressing to complete paralysis. The ability to chew and swallow can also be affected. When all 4 legs are paralyzed, the condition is called “tetraplegia.” Tetraplegia usually occurs within several years of the diagnosis. The dog’s sensory perception abilities are unaffected by this disease, and most affected dogs do not suffer from pain.
Symptoms of Degenerative Myelopathy – What the Owner Sees
Owners of dogs with degenerative myelopathy may notice one or more of the following signs as their dog’s disease progresses:
- Dragging of the rear paws; knuckling-over on the rear toes
- Sores on top of the rear paws
- Abnormal wear of the rear toenails
- Lameness; limping (starts in the hind end; progresses to the forelimbs)
- Spastic, long-strided rear movement
- Difficulty jumping, running, rising or walking
- Balance and coordination abnormalities (ataxia)
- Muscle wasting of the hindquarters from disuse and neurogenic atrophy; mild to progressively profound
- Incomplete paralysis of the hind legs (paraparesis)
- Complete paralysis of the hind legs (paraplegia); inability to stand or walk
- Incontinence (urinary and/or fecal)
- Urine scalding
- Bed sores
- Incomplete paralysis of all legs (tetraparesis)
- Complete paralysis of all four legs (tetraplegia)
- Difficulty chewing or swallowing
- Difficulty breathing
Some owners mistakenly assume that their older pets are developing arthritis, when DM is actually the culprit. Affected animals usually become incontinent late in the course of the disease, although they do not seem to be painful. In fact, one of the key clinical features of canine degenerative myelopathy is the absence of any localizable spinal pain.
Dogs at Increased Risk
Degenerative myelopathy is most often diagnosed in aging German Shepherds. Other breeds that have been reported with DM include the American Eskimo, Belgian Shepherd, Bernese Mountain Dog, Boxer, Cardigan Welsh Corgi, Chesapeake Bay Retriever, Collie, Giant Schnauzer, Golden Retriever, Great Dane, Irish Setter, Irish Terrier, Kerry Blue Terrier, Kuvasz, Labrador Retriever, Miniature Poodle, Old English Sheepdog, Pembroke Welsh Corgi, Pug, Rhodesian Ridgeback, Siberian Husky, Soft-Coated Wheaten Terrier, Standard Poodle, Weimaraner and Wirehaired Fox Terrier. Mixed breed dogs have also been diagnosed with this disease. The mean age of affected dogs is 9 years, with males and females being affected equally. It is extremely uncommon for young dogs to develop DM.