Degenerative myelopathy typically affects dogs 5 – 14 years. The disease typically presents with a slowly progressive loss of coordination in the hind limbs, increasing weakness, and rear limb muscle atrophy. This occurs because of deterioration of neural tissues in the spinal cord that conduct nerve impulses. Specifically, these changes may be found anywhere throughout the spinal cord, especially as the disease progresses, but they are most severe in the lower back (thoracolumbar) region. The fact that the disease is so prevalent in German Shepherds indicates that the primary origin of the disease is genetic. However, the mode of inheritance is not known.
The initial changes associted with canine degenerative myelopathy develop slowly and are frequently initially blamed on hip dysplasia, as hip dysplasia is another common disease that affects German Shepherds. The first signs are weakness and hind limb incoordination, which are more apparent when the dog is walking on a smooth surface. At first, the disease may be assymetrical, with one side more severely affected than the other. The condition does not appear to cause any pain, and dogs retain the ability to control urination and defecation, but as they become progressively weaker, they will be unable to move to an appropriate spot or assume the necessary posture to eliminate. These signs gradually worsen until the dog is unable to walk, in most cases several months to a year after the neurologic problems are first noticed.
There are several other conditions that can mimic this kind of weakness in the hind end in middle-aged medium to large breed dogs. Therefore, a thorough neurological work-up is necessary to confirm a diagnosis of degenerative myelopathy This includes a full neurological examination, x-rays, myelogram, and/or CT/MRI. Important rule-outs include discospondylitis, myelitis, intervertebral disc herniation/bulging, and spinal tumors/cancer of the spinal column.
There are no specific treatments for canine degenerative myelopathy. Management of the disease is therefore geared toward suggesting ways to help you adjust to your dog’s gradually increasing limitations, and to recognize the point at which euthanasia becomes the most humane option. Adjustments include hooking a towel under the abdomen just in front the rear limbs and pulling up on both ends to aid in walking and posturing to void, or even obtaining a wheelchair to carry the weight of the hind end of the body. Some dogs will be more ammenable to these adjustments than others.
Some veterinarians believe that treating with a combination of increased exercise, vitamin supplementation, and aminocaproic acid helps to slow the progression of degenerative myelopathy, but results are largely anecdotal with no studies available to confirm this.
More research clearly needs to be done on degenerative myelopathy, as there is still much about the disease that we do not understand. As stated earlier, evidence does indeed suggest an autoimmune component to the disease, but degenerative myelopathy certainly does not behave like typical autoimmune diseases. Until such time that research may lead to more effective treatments for degenerative myelopathy, at this time the best strategy in combating the disease is responsible breeding. Please do your part to spare future generations this tragic disease, and refrain from breeding any dog with any signs of this degenerative myelopathy. Because clinical signs don’t develop until well after sexual maturity, it is imperative that you be certain that a dog’s line is free of of degenerative myelopathy or any other inherited disease, before considering breeding.
Roger L. Welton, DVM
Founder and Chief Editor, Web-DVM.net
President, Maybeck Animal Hospital
Article updated 9/26/2012