Degenerative myelopathy (DM), also called chronic degenerative radiculomyelopathy, is a neurodegenerative disease in dogs that affects the spinal cord white matter. The disease, which results in slowly progressive hind-limb weakness and paralysis, and can affect many bodily functions, is similar to familial amyotrophic lateral sclerosis (ALS), more commonly known as Lou Gehrig’s disease, in people. Your dog’s increased panting, which is one degenerative myelopathy sign, may be cause for concern. 

What causes degenerative myelopathy in dogs?

 A mutation in the superoxide dismutase 1 (SOD1) gene appears to cause DM in dogs, and DNA testing through the Orthopedic Foundation for Animals can identify dogs with this gene mutation. DNA testing can establish that:

• A dog is DM clear because they have two normal copies of the gene

• A dog is a DM carrier because they have one normal and one abnormal copy of the gene

• A dog is at a much higher risk for developing DM because they have two copies of the mutated gene

Only dogs with two copies of the mutated SOD1 gene can develop DM. However, dogs have been reported with two copies of the mutated gene who did not develop DM, suggesting that other causes are at play. Much about the disease causes and development probability still needs researching. 

What are degenerative myelopathy signs in dogs?

DM typically doesn’t appear in dogs until they’re at least 8 years old, although some dogs do not show signs until they’re 14 or 15. Occasionally, dogs younger than 8 will develop DM.

Initially, affected dogs will show coordination issues, and common early signs include:

• Swaying in the hind end, despite the dog standing still
• Falling over easily 
• Difficulty getting up from a down position
• Knuckling, or turning under, the rear paws, especially when turning
• Scraping the rear paws when walking
• Irritation and alopecia on the top surface of the rear paws
• Losing hind-end coordination

Early DM cases may be confused with orthopedic disorders, like hip dysplasia or osteoarthritis, so a comprehensive work-up is necessary for an accurate diagnosis. 

These signs become progressively worse as the disease develops, typically over the course of six months to a year. And, as the disease progresses, organ failure and respiratory issues will develop. If the disease advances before humane euthanasia is considered, dogs can die from respiratory distress or complete organ failure.

What breeds are most commonly affected with degenerative myelopathy?

DM is most common in German shepherds, Pembroke Welsh corgis, boxers, Rhodesian ridgebacks, and Chesapeake Bay retrievers. However, the condition has been diagnosed in many other dog breeds, including:

• American Eskimo dog
• Bernese mountain dog
• Borzoi
• Cardigan Welsh corgi
• Golden retriever
• Great Pyrenees
• Kerry blue terrier
• Poodle
• Pug
• Shetland sheepdog
• Soft-coated wheaten terrier
• Wire fox terrier

How is degenerative myelopathy diagnosed in dogs?

DM is typically diagnosed through the elimination of diseases with similar signs, like orthopedic issues. A full orthopedic and physical exam will be conducted, which will help differentiate between neurodegenerative and orthopedic disease. DM is a non-painful condition, whereas osteoarthritis and hip dysplasia are uncomfortable. Additionally, a dog with DM will have proprioceptive deficits, meaning they cannot tell if their paws are positioned correctly when placed upside down. 

Your family veterinarian may also suggest myelography, an MRI, or a cerebrospinal fluid tap, to rule out compressive and inflammatory diseases. At that point, a DNA test, to determine if your dog has two copies of the mutated gene, will help provide a conclusive diagnosis. 

How is degenerative myelopathy treated in dogs?

DM in dogs has no cure, but, fortunately, is not a painful condition. Treatment is focused on supportive care to help assist with mobility, urinating, and defecating.

What prognosis can I expect for my dog with degenerative myelopathy?

As the disease progresses, your dog’s mobility will be greatly impaired, and organ dysfunction and respiratory impairment will also set in. Most dogs are humanely euthanized because of disability one to three years after their initial DM diagnosis.

If your senior dog has received a degenerative myelopathy diagnosis, consider supporting them through their final days with veterinary hospice care. And, when the time comes, contact a Lap of Love veterinarian in your area to schedule a peaceful passing with in-home euthanasia.