Description or definition:
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Hereditary Canine Spinal Muscular Atrophy (HCSMA) is a motor neuron disease that cause degeneration of motor neurons in the anterior (near the head) section of the spinal cord. Motor neurons are the nerve cells that convey impulses to the muscles to produce movement. Accordingly, this condition results in significant muscular weakness and atrophy. A subcategory of the condition called German Shepherd Focal Spinal Muscular Atrophy often seen in dogs of German Shepherd heritage is thought to involve a smaller area of motor neuron damage. |
Symptoms:
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Degeneration of motor neurons causes progressive weakness with difficulty in supporting weight, reduced reflexes, abnormal gait, muscle tremors, and loss of muscle tone/mass (muscle atrophy). |
Once initial muscle weakness is observed, the condition generally becomes rapidly progressive. The condition is considered “accelerated” if initial weakness is noted prior to 1 month of age and progresses rapidly, “ intermediate” if initial weakness noted at 4‑6 months of age and progresses rapidly, and “chronic” if the initial weakness is noted in an older puppy and progresses slowly. Accelerated motor neuron disease generally results in paralysis before the age of six months, and intermediate motor neuron disease by 2-3 years of age. Dogs with the “chronic” form of motor neuron disease may live well into their adult lives. Similarly, the effects of focal spinal muscular atrophy often seen in breeds of German Shepherd heritage can be relatively mild and slow to progress. Additionally, unlike some other forms of motor neuron disease, the weakness or paralysis may be limited to the tail, hind end, or even just one limb.
Diagnosis:
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Diagnosis is based on a thorough neurologic examination, the absence of abnormalities on routine diagnostic tests, and the progressive nature of the condition. Specific diagnostic tests might include testing the dogs reflexes, muscle biopsy, and electronic nerve conduction studies. |
Treatment:
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There is presently no effective treatment for this condition. |
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| Jessica in Arizona |