By Dr. Becker
Degenerative myelopathy, or DM, is a disease of the spinal cord in dogs. It typically occurs between the ages of 8 and 14. Younger dogs can acquire the disease, but it is uncommon.
DM is most often seen in German shepherds, but other large breed dogs can be affected, including the Belgian sheepdog, Chesapeake Bay retriever, Great Pyrenees, Labrador retriever, Old English sheepdog, Rhodesian ridgeback, and the Weimaraner.
Degenerative Myelopathy Symptoms
The disease begins with the loss of coordination in the hind limbs. Dogs with degenerative myelopathy wobble when they walk, they can knuckle over, or they can begin dragging their hind feet.
The first symptoms usually occur in one hind limb and then affect the other. As the disease progresses, the limbs become weaker and the dog has difficulty standing. Ultimately, the dog becomes unable to walk.
The course of DM ranges from about six months to a year before a dog is paraplegic, losing complete function of the rear limbs. Sometimes the disease continues to progress, causing a loss of bladder and bowel control and eventually, weakness will also develop in the front limbs. As devastating as the disease is, fortunately, it is not a painful condition for the dog.
In DM, the myelin sheath that protects the spinal neurons begins to disintegrate, which exposes the underlying nerve fibers and disrupts the communication pathways between the brain and the spinal cord.
The myelin coating around the spinal cord is crucial for healthy brain-body communication. When myelin degenerates, so does the ability of the brain to send commands to the limbs, and for sensory information to travel from the limbs to the brain.
Causes of Canine Degenerative Myelopathy
It is suspected DM is an immune-mediated disease somewhat like MS in people. The dog’s immune system attacks its nervous system.
Other theories of why DM occurs include toxins, vitamin deficiencies, oxidative stress, or an underlying spinal injury.
Because DM is prevalent in certain breeds, a genetic component is likely. Recent research has identified a mutation in a gene that confers a greatly increased risk of developing this disease.
DM is a diagnosis of elimination. In other words, many other diseases must be ruled out before a definitive diagnosis can be made. These include a herniated disc or intervertebral disc disease, infections, injuries, cysts, tumors, and stroke. Since many of the diseases with similar symptoms can be successfully treated, it’s important to rule all of them out first.
Diagnostic tests to rule out other diseases include myelography and an MRI.
Once a presumptive diagnosis of DM is made, the only way to absolutely confirm it is to examine the spinal cord during autopsy to check for degenerative changes that are normally seen in DM but are not seen in other spinal cord diseases.
Options for Managing the Disease
Unfortunately, degenerative myelopathy is a progressive disease with no cure, and there are no drug protocols that have consistently worked to slow the degeneration. Once a dog has been diagnosed with DM, the treatment goal is to manage the consequences of the disease and maintain good quality of life for as long as possible.
Dogs with degenerative myelopathy can experience a number of secondary problems resulting from the disease, including urine retention, urinary tract infections, weight gain and muscle loss from inactivity, skin lesions from incontinence, and bedsores as well. Once a dog is diagnosed with DM, scrupulous nursing care will be required for the duration of his life.
In my opinion, the very best approach to managing this condition is with an integrative protocol instituted at the earliest onset of clinical signs.
A key to maintaining a DM dog’s quality of life and slowing the progress of the disease is maintaining rear limb muscle tone. Regular exercise such as walking for as long as the dog is able, in addition to range of motion exercises and other forms of physical therapy can delay the muscle atrophy associated with DM and maintain mobility and muscle strength for as long as possible. This is absolutely critical.
Hydrotherapy and targeted exercises to maintain rear limb strength may also slow the progression of this disease and help dogs with DM maintain strength, balance, and mobility for a much longer period of time. Acupuncture can also be very beneficial in stimulating the nervous system of these dogs.
As the disease progresses, there are a variety of harnesses, wheelchairs (or carts, as they’re called for dogs), boots and slings that can also help to improve quality of life and maintain mobility.
Potentially Beneficial Supplements
Most holistic veterinarians, including me, recommend dietary supplementation for dogs with degenerative myelopathy. In addition to a fresh food diet, two supplements -- aminocaproic acid and N-acetylcysteine, also called NAC -- have proved beneficial (and very much so in some cases) in slowing the progression of the disease.
Additionally, vitamins E (with selenium) and C, B-complex vitamins, ubiquinol, bromelain, as well as herbs such as ginseng and gingko, are also recommended.
Adding omega-3 fatty acids such as salmon or krill oil, as well as a source of GLA, which are the gamma-linolenic acids like blackcurrant seed oil, are also suggested. In addition, I recommend you consider adding a potent antioxidant such as grape seed or pine bark extract, both of which can be beneficial.
Most importantly, if your large breed dog is developing rear limb weakness, I strongly encourage you to visit your veterinarian as soon as possible. The earlier a diagnosis is made, the faster you can begin aggressively supporting your dog with targeted muscle-building exercises and an excellent nutritional supplement protocol.