Canine dysautonomia is a degenerative polyneuropathy characterized by neuronal degeneration within the autonomic, somatic, central, peripheral, and/or enteric nervous system, causing multisystemic effects similar, if not identical, to the dysautonomia in horses Equine Dysautonomia Equine dysautonomia (grass sickness) is a disease characterized by degeneration of autonomic neurons in the brain, ganglia, and enteric nervous system. Clinical signs include GI hypomotility... read more 
, cats Feline Dysautonomia The dysautonomias are a group of diseases with strikingly similar clinical and pathologic signs reported in a number of unrelated species, including horses, dogs, cats, rabbits, and hares. The... read more 
, rabbits Leporine Dysautonomia The dysautonomias are a group of diseases with strikingly similar clinical and pathologic signs reported in a number of unrelated species, including horses, dogs, cats, rabbits, and hares. The... read more 
, and hares. Canine dysautonomia was first described in England in 1983, but the disease has not been diagnosed there for many years. Although individual cases have been reported in Scotland, Norway, Belgium, Germany, and Greece, canine dysautonomia is less commonly reported in Europe than in the USA, with higher numbers primarily in the Midwest. In the USA, risk factors were reported to include a rural habitat and spending >50% of the time free outdoors.
Clinical Findings
The most consistent history and physical examination findings are:
Secondary effects of autonomic dysfunction, such as aspiration pneumonia and lethargy, may develop. Weight loss is often dramatic.
Laboratory findings are nonspecific. Pharmacologic testing of the pupils is probably the best single test to confirm the diagnosis. Dilute pilocarpine (0.05% ophthalmic solution) results in rapid pupillary constriction in dogs with dysautonomia because of supersensitivity of the denervated muscle to cholinergic drugs. The prognosis is grave.
