Neurogenic diabetes insipidus in a sheep.

A 7-month-old Suffolk-cross ram was examined because of polydipsia and polyuria of 2 months" duration. Neurogenic diabetes insipidus was diagnosed on the basis of failure to concentrate urine of low specific gravity in response to water deprivation and a positive response to antidiuretic hormone administration. Post-mortem examination of the brain revealed degeneration in the cerebral peduncles, an absence of pituitary neural tissue and evidence suggesting external pressure as the cause.