Degenerative myelopathy

Degenerative myelopathy is a progressive spinal cord disease which eventually causes severe weakness or paralysis of all four legs as well as other complications. Most dogs die from complications (or euthanasia) within 2 years of diagnosis.

©Antonio Florentini / Pexels

The myelin sheath is a thin layer of tissue that covers many nerves in the body. Myelin helps protect the spinal cord and nerve cells and promotes faster nerve conduction but in degenerative myelopathy, the myelin covering certain areas of the spinal cord and associated nerves begins to break down. The nerves become damaged, leading to impaired nerve conduction and progressive muscle weakness that usually starts in the rear legs but develops into severe weakness or paralysis of all four limbs.

Degenerative myelopathy is a genetic condition that can affect the German shepherd, Corgi, Siberian husky, Rhodesian Ridgeback and Boxer. Mixed-breed dogs can also be affected. Dogs are usually middle-aged or older when they develop signs of disease, so early signs may be mistaken for arthritis or other conditions affecting the lower back and rear legs.

Affected dogs may initially develop weakness in the rear legs. They may stumble with their rear feet and seem unaware of the location and position of their feet. They may knuckle with the rear paws (walk so the tops of the paws contact the floor or ground) or drag the tops of the paws along the floor or ground. This leads to abnormal nail wear and scrapes on the tops and sides of the toes.

As the disease progresses, weakness in the rear legs can progress to complete paralysis. Muscle atrophy (wasting) can occur from reduced limb use and damage to the nerves in the area.

By the end stage of the disease, all four legs are severely weak or paralyzed as nerves higher up in the spinal cord are affected. Urinary and fecal incontinence may occur, along with body-wide muscle wasting.

Degenerative myelopathy is considered a diagnosis of exclusion – the diagnosis is generally confirmed by ruling out other spinal cord and neurologic conditions that could be causing the pet’s clinical signs.

Your veterinarian will likely begin the diagnostic process with a medical history and thorough physical examination (including orthopaedic and neurologic evaluations). Blood and urine tests may be recommended to rule out other illnesses.

Additional testing may include spinal radiographs (x-rays), magnetic resonance imaging (MRI), and computed tomography (CT). These test results may be normal in a dog with degenerative myelopathy, but they can often rule out other diseases.

Nursing care is essential to preserving a pet’s overall well-being, cleanliness, and quality of life for as long as possible. The disease is not painful and soft bedding (to help minimize bed sores), physical therapy (to help slow muscle atrophy), and frequent bathing (to manage urinary and fecal incontinence) are just a few of the things necessary to help manage a dog with this condition.

Dogs that can’t walk are often reluctant to urinate, so dogs with degenerative myelopathy may hold their urine for too long, leading to urinary tract infections. Helping the dog outside frequently to eliminate may help, but this can be difficult if the dog is very large or heavy. Antibiotics may be needed periodically to treat urinary tract infections and skin wounds (from urine scalding and bed sores). Periodic bacterial culture testing of urine to make sure infections are appropriately treated may also be recommended.

Unfortunately, there is no cure for degenerative myelopathy, and the long-term prognosis is poor. Most dogs with this disease are partially paralyzed (starting with the rear legs) within 9 months after diagnosis and are severely weak or completely paralyzed in all four legs within 2 years. Many affected dogs are euthanased before the disease progresses to the end stage.