Canine degenerative myelopathy, also known as chronic degenerative radiculomyelopathy and German shepherd myelopathy, is a slowly progressive disease. Similar to Lou Gehrig’s disease in humans, degenerative myelopathy affects a dog’s spinal cord and central nervous system, leading to muscle weakness, deterioration and paralysis.
Degenerative myelopathy occurs when structures in the spinal cord responsible for nerve impulses degenerate. Myelin, the insulation around the nerves in the spine, and the nerve fibers that carry signals to the muscles fail to communicate. DM can onset anywhere along the spinal cord, but mid to lower back is most common.
The majority of dogs with DM are greater than 5 years old. Dogs with early stage degenerative myelopathy develop non-painful weakness in the hind legs and an unsteady gate. You may notice him dragging his paws or knuckling over on his rear paws. Other early signs include stumbling, difficulty rising, rear leg tremors and worn nails. Late stage DM symptoms include incontinence, front leg weakness, anxiety, pressure sores, inability to rise, muscle atrophy, infection, organ failure, difficulty breathing, collapse, seizure and incomplete or complete paralysis.
Degenerative myelopathy is a hereditary disease caused by a DNA mutation in a gene called superoxide dismutase 1 (SOD1). It is most common in German shepherds, though other breeds such as Pembroke Welsh corgis, American water spaniels, Bernese mountain dogs, bloodhounds, borzois, boxers, Canaan dogs, Chesapeake Bay retrievers, English cocker spaniels, Kerry blue terriers, pugs, Sealyham terriers and whippets can also carry the mutated gene.
Canine degenerative myelopathy is fairly uncommon and can mimic a variety of other disorders such as the more common hip dysplasia. Your veterinarian may perform a battery of diagnostic tests including physical and neurological examinations, blood work, X-rays and CT and MRI scans, as well as DNA testing if he suspects DM.
Unfortunately, treatment will not reverse DM, but it may help manage it for a while; canine degenerative myelopathy is a fatal disease. Discuss management options, such as vitamin supplements and therapeutic exercise, with your veterinarian. As for prognosis, each individual dog is unique, and while some diagnosed with degenerative myelopathy will succumb within six months, others can live for up to three years with the disease.
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