Progressive myelopathy is a degenerative neurologic disease affecting spinal cord. The cause is unknown origin and possible hereditary basis is suspected. The disease is similar to multiple sclerosis in humans. It destroys the myelin sheath (a protective coating around nerve fibers) and has a poor prognosis. Myelin is a substance made of fat and protein that surrounds and insulates nerve fibers; it helps speed up nerve impulse transmission both in the spinal cord and in the nerves. This progressive condition mainly affects German Shepherd dogs and is fairly common in the breed. It may also occur in other breeds, such as Siberian Hiskies and other large breeds. The disorder tends to appear wen the dog is about 6 years of age.
Affected dogs experience a slow and painless loss of coordination in the hind legs. Early in the course of the disease, many dog owners erroneously assume that weakness in the hind legs is caused by a problem with the hip joint. Over the following years the weakness evolves into a partial paralysis. The dog seemingly cannot feel where its paws are, but its pain perception remains intact, as does voluntary control over urination and defecation. Weakness evident on rising may be the first indication of the disease. As many German Shepherds and other large breeds commonly develop osteoarthritis of the hips and stifles and spondylosis deformans, difficulty rising may be attributed to discomfort associated with these disorders.
Diagnosis of degenerative myelopathy can be difficult. Survey spinal radiographs and a myelogram may reveal only areas of possible pachymeningitis. When degenerative myelopathy is suspected, a mitogen response assay is used to confirm this diagnosis which may fail to indicate degenerative myelopathy as the cause of clinical signs. Sometimes the diagnosis can only be confirmed at necropsy when classic histopathologic lesions of degenerative myelopathy are noted in the spinal cord. Electromyograms (EMGs) may be performed as well to evaluate electrical activity associated with the muscle tissue of the body.
While many treatments have been attempted, none has been shown to slow down or reverse the damage. Weight control is important, as is routine daily exercise to maintain muscle tone. Anabolic steroids may be given to strengthen the muscles. Therapy includes exercise, vitamin supplementation, and EACA medication. Avoiding unnecessary surgical procedures is also important to preclude permanent deterioration that can result following surgery in DM patients. In dogs other than German Shepherds, other identifiable causes should be treated. Physiotherapy proves to be beneficial in treating dogs with this condition. In general, animals that received intensive physiotherapy have longer survival time, compared with that for animals with moderate physiotherapy. Affected dogs which receive physiotherapy remaine ambulatory longer than did animals that did not receive physical treatment. However, in the long run, motor incapacitation is inevitable.
- Daily controlled physiotherapy increases survival time in dogs with suspected degenerative myelopathy. Kathmann I, Cizinauskas S, Doherr MG, Steffen F, Jaggy A.
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