What to Know About Degenerative Myelopathy in Dogs

Medically Reviewed by Amy Flowers, DVM on December 06, 2021
Written by Cheryl Whitten
3 min read

Degenerative myelopathy in dogs, or DM, affects the spine and leads to disability. It affects older dogs and gets worse over time.

DM is a spinal cord disease in which the white matter of the spinal cord breaks down. It slowly worsens until your dog loses coordination and is unable to walk. 

After the white matter around the nerve fibers wastes away, the nerves can’t carry signals to the muscles. Without these signals, muscles don’t contract, and your dog is unable to move. Degeneration can happen anywhere along the spine, but it usually affects the middle to lower back.

The disease is also called chronic degenerative radiculomyelopathy or German shepherd degenerative myelopathy, because DM commonly affects certain breeds like German shepherds. 

Other commonly affected breeds include:

  • Boxers
  • Pembroke Welsh Corgis
  • Rhodesian Ridgebacks
  • Chesapeake Bay retrievers

DM also usually affects older dogs, and is rarely seen in dogs under age 5. 

DM is caused by inherited changes to a gene called superoxide dismutase 1, or SOD1. This gene gives instructions to the superoxide dismutase enzymes, which act as antioxidants and help rid the body of free radicals. When these irregular genes are present, free radicals build up in the body and cause damage.

People can also have SOD1 gene changes, which causes Lou Gehrig’s disease or amyotrophic lateral sclerosis (ALS). 

DM is an autosomal recessive genetic disease, which means your dog must have two copies of the changed genes to have symptoms of DM. They will then pass the gene to their offspring.

If your dog only has one copy, they are a carrier for the disease and have a low risk of getting the disease. They also have a 50% chance of passing a copy of the gene to their puppies. 

DM happens slowly. Some of the first signs are stiffness and awkwardness in the back legs while the dog is getting up. You might notice this occurs more frequently on smooth surfaces. As the disease worsens, your dog might scuff their toes or nails while they walk. 

Other early signs include:

Sometimes, early degenerative myelopathy in dogs is mistaken for arthritis or other bone/joint diseases. One key difference is that DM doesn’t cause any pain.

Eventually, your dog will be unable to move their legs as the disease advances to paralysis. They will also have symptoms like:

Advanced DM eventually leads to weakness and paralysis in all limbs. Dogs with DM usually aren’t able to walk within a year of showing symptoms.

DM can look like other diseases like a herniated disc or cancer, so your vet will run tests to rule those out. These can be:

  • Blood tests
  • Spinal X-ray
  • Spinal fluid testing
  • Computed tomography scan (CT) scan
  • Magnetic resonance imaging (MRI)
  • DNA testing

There is no cure or treatment for degenerative myelopathy in dogs. Your vet might offer different therapies to help with symptoms, including:

  • Physical therapy. Swimming and walking can help keep muscle mass in the back legs and keep your dog moving longer.
  • Vitamins. In some cases, your vet might recommend vitamins and supplements like vitamin B, C, and E and N-acetyl-cysteine. It’s not clear that these work any better than physical therapy, though.
  • Wound care. Once your dog is unable to move, they might get pressure sores that need to be cleaned and bandaged. 
  • Hygiene. You’ll need to clean your dog’s bedding and living area daily when they lose bowel and bladder control.

There is no cure for DM, and dogs don’t survive the disease. While some dogs are able to stay moving for longer periods with physical therapy, degenerative myelopathy gets worse with time. Eventually, they will become paralyzed in all limbs. 

Caring for a large dog can be hard, and most people choose euthanasia once the dog is unable to walk or move, which often happens around 1 year after symptoms start.

If your dog has trouble moving or bowel and bladder problems, talk to your vet.