Central diabetes insipidus in dogs: 20 cases (1986-1995)

Objective - To assess clinical signs, biochemical findings, results of modified water deprivation and other diagnostic tests, response to treatment, and survival time in dogs with central diabetes insipidus (CDI). Design - Retrospective study. Animals - 20 dogs with CDI. Procedure - Signalment, history, physical examination, results of diagnostic tests, response to treatment, and survival time were extracted from the medical record of each dog and supplemented with information obtained from owners via telephone. Results - Isosthenuria or hyposthenuria was a consistent finding. Seven dogs with complete CDI and 13 dogs with partial CDI were identified on the basis of results of a modified water deprivation test. Dogs treated with desmopressin acetate responded well to treatment. Seven dogs were alive 18 to 72 months (median, 36 months) after diagnosis, and 10 dogs died or were euthanatized 1 week to 2 years (median, 2 months) after diagnosis. Seven of 10 dogs that died developed neurologic signs after diagnosis of CDI. Computed tomography revealed a mass in the region of the pituitary gland in 5 of 7 dogs. Necropsy of 6 dogs, including 2 dogs on which computed tomography had been performed, revealed neoplasia in the pituitary gland. Clinical implications - Onset of neurologic signs after diagnosis of CDI in middle- to old-aged dogs indicates that CDI may not be a benign disease that is treated easily. Brain imaging is recommended after diagnosis of CDI in middle- to old-aged dogs. Also, because many dogs are isosthenuric on initial examination, CDI cannot be ruled out as a cause of polyuria and polydipsia on the basis of lack of hyposthenuria.