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 can be better prepared for how to manage this condition, in order to provide the best quality of life possible for their pet.
What is Degenerative Myelopathy in Dogs?
Degenerative myelopathy is often abbreviated as DM, and is a disease that affects the white matter of the spinal cord. In DM, this part (the white matter) of the spinal cord starts 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.
Signs of Degenerative Myelopathy in Dogs
As symptoms of degenerative myelopathy progress, they become more obvious to the owner, but initially they may not be so apparent.
- Swaying in the hind end when standing
- Easily falls over if pushed
- Knuckling of the paws when trying to walk
- Feet scraping on the ground when walking
- Abnormally worn toenails
- Difficulty walking
- Difficulty getting up from a sitting or lying position
- Falling down when walking or standing
- Inability to walk
- Paralysis of the hind limbs
The first signs of degenerative myelopathy in dogs are subtle. They usually occur in dogs over eight years of age. Initially, a dog with DM may wobble or sway a bit when standing still. The dog may have trouble getting up from a sitting or lying position and may easily fall over if it loses its balance. As the disease progresses, symptoms worsen and the hind limbs get weaker. The feet may scrape on the ground when the dog tries to pick them up to walk, and knuckling of the paws may occur. Excessively worn claws (toenails) and/or wounds to the feet may occur as a result. 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 in Dogs
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.
Risk Factors for Developing Degenerative Myelopathy
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
- Cardigan Welsh Corgis
- Chesapeake Bay Retrievers
- German Shepherd Dogs
- Golden Retrievers
- Great Pyrenees
- Kerry Blue Terriers
- Pembroke Welsh Corgis
- Rhodesian Ridgebacks
- Shetland Sheepdogs
- Soft Coated Wheaten Terriers
- Wire Fox Terriers
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. A full medical history will also be taken, 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.
Treatment of Degenerative Myelopathy in Dogs
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 terrible disease. Physical therapy, 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.
How to Prevent Degenerative Myelopathy in Dogs
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.
Degenerative Myelopathy in Dogs. VCA Hospitals.
Degenerative Myelopathy. University of Missouri Veterinary Health Center.
Degenerative Myelopathy (DM). UC Davis School of Veterinary Medicine.
Degenerative Diseases Of The Spinal Column And Cord - Nervous System. Veterinary Manual, 2020