Degenerative Myelopathy in Dogs

Degenerative myelopathy affects dogs in a major way, but initially it may be confused with other conditions or disease processes. By understanding more about this genetic issue, a dog owner that is seeing signs of degenerative myelopathy, such as limb weakness, can be better prepared for how to manage this condition to provide the best quality of life possible for their pet.

What Is Degenerative Myelopathy?

Degenerative myelopathy (also known as DM) is a disease that affects the white matter of the spinal cord, causing it to break down, or degenerate, which results in weakness of the hind limbs that eventually progresses to paralysis. With time, the front legs can also be affected. It is similar to some of the forms of human amyotrophic lateral sclerosis (ALS), which is more commonly known as Lou Gehrig’s disease. This disease is obviously devastating to a dog owner, as it eventually results in the loss of function that is so necessary for many of a dog's normal activities.

Symptoms of Degenerative Myelopathy in Dogs

The first signs of degenerative myelopathy in dogs are subtle. They usually occur in dogs over eight years of age. As symptoms of degenerative myelopathy progress, they become more obvious to the owner, but initially they may not be so apparent. The progressive signs and symptoms of DM may include:

Swaying and Wobbling

Initially, a dog with DM may wobble or sway a bit in the hindquarters when standing still. The dog will also easily fall over if slightly pushed. But the dog is not in pain.

Feet Scraping and Knuckling of Paws

As the disease progresses, symptoms worsen and the hind limbs get weaker. This can cause the feet to scrape on the ground when the dog tries to pick them up to walk, resulting in the loss of hair and an increase in irritation to the skin. Knuckling of the paws may occur, starting with the hind paws. The dog will begin to turn its knuckles under and try to walk on them.

Worn Toenails

Excessively worn claws (toenails) and/or wounds to the feet may occur as a result of the dog's inability to walk correctly.

Difficulty Walking and Getting Up

The dog may have trouble getting up from a sitting or lying position. When the dog does stand up, it has a very tough time walking. At this stage it may also be difficult walking up steps and squatting to defecate.

Falling Down

As the disease progresses, the dog may easily buckle at the knees and fall over if it loses its balance, even without a gentle push.

Inability to Walk and Paralysis

Eventually, a dog with DM will fall down when trying to walk and may develop complete paralysis of the hind limbs. The disease will eventually progress to affect the front limbs as well.

Causes of Degenerative Myelopathy

The cause of degenerative myelopathy in dogs is a mutation in a gene called superoxide dismutase 1 (SOD1). The risk factor was identified in 2009.

Diagnosing Degenerative Myelopathy in Dogs

The initial symptoms of degenerative myelopathy can look like those of other diseases, so a full physical examination and often some diagnostic testing are required to rule out other causes of hind limb weakness. The veterinarian will also take a full medical history, along with consideration of the breed and age of the dog. Diagnostic tests such as X-rays, CT and MRI scans, and cerebrospinal fluid (CSF) analysis may be performed, as well as a biopsy of the spinal cord. This is not commonly performed though, and the diagnosis of DM is typically made after ruling out other potential diseases.

A DNA test to check for the SOD-1 gene mutation is available and is often recommended for at-risk breeds. This test is offered through multiple laboratories.

At-risk breeds include:

• American Eskimo Dogs
• Bernese Mountain Dogs
• Borzoi
• Boxers
• Cardigan Welsh Corgis
• Chesapeake Bay Retrievers
• German Shepherd Dogs
• Golden Retrievers
• Great Pyrenees
• Kerry Blue Terriers
• Pembroke Welsh Corgis
• Poodles
• Pugs
• Rhodesian Ridgebacks
• Shetland Sheepdogs
• Soft Coated Wheaten Terriers
• Wire Fox Terriers

Treatment

There is no cure for degenerative myelopathy in dogs. Treating the symptoms as they progress can help maintain a good quality of life in a dog that has been diagnosed with this disease. Exercise, walking, swimming, and physical therapy are vital to prolonging the quality of life of a dog with DM. Special hind-end harnesses to aid a dog in walking, preventing foot damage, increasing traction by walking a dog on grass instead of concrete, and placing rugs on slippery floors may help delay the need for euthanasia.

Prognosis for Dogs With Degenerative Myelopathy

The symptoms of a dog with degenerative myelopathy will quickly worsen after diagnosis. The spinal cord will continue to degenerate, the dog will have trouble standing up from laying down, and mobility will become more difficult as time goes on. Eventually, a dog with DM will become incontinent. The final stage of DM is paralysis.

How to Prevent Degenerative Myelopathy

The only way to prevent degenerative myelopathy in dogs is to selectively breed. Before purchasing an at-risk dog, ask the breeder to show you the results of SOD-1 gene mutation testing on the parents, proving that both carry two copies of the normal gene.