Dysautonomia in dogs and cats

Dysautonomia in dogs and cats is an idiopathic condition that causes loss of automatic nervous system functions. Clinical signs vary substantially. Megaesophagus and subsequent regurgitation are common (not invariable); however, dysuria and a distended urinary bladder, mydriasis, and lack of pupillary light response, dry mucus membranes, weight loss, constipation, vomiting, and anorexia are reported. There appear to be geographic areas (e.g., Missouri and surrounding states), that currently have an increased incidence of the disease for some reason.

Dysautonomia in dogs and cats is usually suspected clinically by finding dysuria, dry mucus membranes, and abnormal pupillary responses. Radiographs revealing distention of multiple areas of the alimentary tract (e.g., esophagus, stomach, small intestine) also are suggestive. A presumptive, antemortem diagnosis is usually made by observing the effects of pilocarpine on pupil size after 1 to 2 drops of 0.05% pilocarpine are placed in one eye only. Finding that the treated eye rapidly constricts whereas the untreated eye does not is consistent with dysautonomia in dogs and cats.

Similarly, finding that a dysuric dog with a large urinary bladder can urinate after administration of 0.04 mg bethanechol/kg SQ is also suggestive (although not all affected animals respond). Definitive diagnosis requires histopathology of autonomic ganglia, which can only be obtained at necropsy.

Treatment is palliative. Bethanechol can be given (1.25 to 5 mg daily) to aid in urinary evacuation. The urinary bladder should be expressed as needed. Gastric prokinetics (e.g., cisapride) may help lessen vomiting. Antibiotics may be administered for aspiration pneumonia secondary to megaesophagus.

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