Head trauma as a possible cause of central diabetes insipidus in a cat.

A 13-month-old female domestic shorthair cat presented with a 10-month history of polyuria and polydipsia that began after having been hit by a car. Neurological examination revealed visual deficits and an absent bilateral menace response. Hematological and serum biochemical analyses were within reference values, but hyposthenuria was identified. Failure to concentrate urine during the water deprivation test followed by an increase in urine specific gravity after administration of synthetic antidiuretic hormone (ADH) suggested a diagnosis of central diabetes insipidus. Subcutaneous or oral administration of synthetic ADH was effective in central diabetes insipidus treatment during the 19-month follow-up.