Degenerative myelopathy is a disease of the nervous system of dogs, which affects nerves at the level of the spinal cord. It is found most commonly in German Shepherds, but has been diagnosed in over 100 breeds, including Cardigan and Pembroke Welsh Corgis, Rhodesion Ridgebacks, Chesapeake Bay Retrievers, and Boxers. The disease is seen in dogs that carry mutations in the SOD1 gene. SOD1 is superoxide dismutase, which is a gene responsible for repairing oxidative damage to cells. Cells containing high amounts of lipid (fats) are the most susceptible to oxidative damage. Nerve cells are coated with myelin, which is a form of lipid, so damage to nerve cells will occur if SOD1 is not working. This is one of the reasons the disease does not show up until later in life - it takes many years of oxidative damage to become symptomatic. Dogs that do not carry the SOD1 mutation are never afflicted with the disease. This same gene mutation is found in people suffering with ALS or Lou Gehrig's disease.
Symptoms of DM include hind end weakness which progresses to hind end paralysis, and eventually to paralysis of all muscles throughout the body. Dogs that lose hind end function will often do well with a hind end cart until the front limb muscles also become paralyzed. Slings and booties can also help. Eventually, all muscles in the body will become paralyzed and the animal will succumb to respiratory failure. Most pet owners elect euthanasia six to twelve months after diagnosis.
At this time there is no effective treatment for DM. Medications like low dose Naltrexone (Skip's Pharmacy), aminocaproic acid, N-acetylcysteine, and supplements like ubiquinol, selenium, Vitamins B, C, and E, bromelain,omega 3 fatty acids, gingko, and ginseng have all been recommended. Treatments like chiropractic adjustments and electroacupuncture may stimulate better nerve function. Keeping the muscles as strong as possible with exercise and physical therapy is an important component to maintaining mobility for as long as possible.These dogs should be kept free of stress, as this disease seems to have some long term,stress-related component.
Recommended doses for some antioxidant supplements include Vitamin E 1,000-2,000 IU per day, Vitamin C 1000-2000 mg per day, B-complex - 2 high potency capsules per day or stress formulation 1 capsule per day, Selenium 100 (small dog) to 200 (large dog) ug/day, and Aminocaproic Acid 250 mg/ml suspension, mix 2 ml with 1 ml chicken broth and give every 8 hours.
Genetic testing for DM is available through the University of Missouri with samples of saliva from a cheek swab or through blood DNA testing. This has made diagnosis easier, as a dog must have two bad copies of the SOD1 gene in order to be symptomatic. DM is not diagnosed with MRI, CT scan, or other testing, but these may be used to rule out other diseases.
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