Test Overview:

Greyhound polyneuropathy is a disease that occurs in “show lines” of greyhounds. It is a neurologic disease caused by a mutation on the NDRG1 gene. This is an autosomal recessive disease that causes peripheral nerves to degenerate, leading to muscle weakness and atrophy. Muscle atrophy is a loss of muscle mass, and this occurs because there is a loss of nerve stimulation to the muscle. Studies estimate that a quarter of all show greyhounds are carriers of this disease. Signs of greyhound polyneuropathy are first seen at around 3-4 months of age. There is a sudden onset of abnormal gait, with an arched back and weakness of the hind legs. Puppies exhibit exercise intolerance, and develop a “bunny hopping” gait and cannot fully extend their stifles. They rapidly lose muscle mass and within weeks become unable to walk more than a short distance. Affected animals have severely decreased or absent spinal reflexes (e.g. the patellar reflex) but retain sensation and proprioception, and remain bright and alert right through the disease course. Muscle weakness is progressive until the dog cannot stand or get up. Muscle atrophy is severe, and some dogs may have atrophy of the laryngeal muscles, resulting in an inability to bark, and in some an obstruction to normal breathing. Affected dogs are generally euthanized by the age of 9-13 months. With the recent discovery of the causative genetic mutation and availability of a commercial genetic test for this condition, it should now be possible to avoid producing this disease in puppies. Any carrier should only be bred to a clear mate in order to avoid this disease being seen in the future.