Commonly known as degenerative myelopathy, progressive myelopathy is a disease that affects the spinal cord in dogs, causing paralysis in the hind legs and eventually spreading to the rest of the body. Degenerative myelopathy is common in German shepherds, boxers, and Welsh corgis, but it affects other purebred dogs and mixed-breeds as well.
Progressive myelopathy most often affects dogs age 8 and older, though it sometimes presents in younger dogs. Affected dogs usually have histories of weakness in the hind legs that causes difficulty reaching a standing position, problems walking on slippery floors and issues navigating stairs. As the disease progresses, dogs become prone to urinary and fecal incontinence because the paralysis moves up through the body, much like multiple sclerosis or Lou Gehrig’s disease does in a human being. Degenerative myelopathy itself is not painful for the dog, but the dragging of the hind legs as paralysis sets in can cause painful lacerations on the paws.
The only way to be certain a dog suffered from degenerative myelopathy is to have a veterinarian examine the spinal cord after death. However, he can use techniques to rule out other myelopathies and make a presumptive diagnosis of the disease. The most common methods include a neurological examination of the dog via an MRI, as well as an evaluation of his overall physical health. Most veterinarians also analyze the dog’s cerebrospinal fluid, which helps to rule out other myelopathies. A dog that might have progressive myelopathy will have normal test results, although there may be signs of spinal disc degeneration.
Degenerative myelopathy in dogs is undergoing significant research. Researchers at the University of Missouri and the Broad Institute of MIT and Harvard discovered that dogs at risk of suffering from the disease have a gene mutation similar to that found in human beings suffering from multiple sclerosis. The mutation is in the superoxide dismutase 1 gene. A dog with a homozygous normal gene is unlikely to get the disease. A dog with a heterozygous gene is a carrier of the disease who's unlikely to contract it himself. Sufferers have homozygous affected genes, although not all dogs with an affected gene will have the disease.
Prognosis and Treatment
No cure or medicinal treatment for degenerative myelopathy exists, although measures exist for making the dog’s remaining days more comfortable. Avoiding stairs and light exercise will help the dog to keep use of his hind legs for as long as possible. Swimming is an example of a helpful exercise that does not cause too much stress on the legs. Extra padding in his bed will help keep him comfortable. Once he loses use of his legs, wheelchairs or booties will keep his feet from dragging and help prevent lacerations. In the event that a laceration does occur, immediate treatment is essential to prevent infection. If the dog is obese, reducing his weight will help, as will reducing stress in the home. As the myelopathy progresses, it will take over his urinary and fecal tracts, and eventually his respiratory system. Most owners choose to euthanize affected dogs before it reaches the respiratory system. This generally happens within six months to a year after diagnosis, although some dogs live longer with proper care.