Syndrome of inappropriate antidiuretic hormone secretion in a dog with a histiocytic sarcoma.

A 7-year-old female neutered Bernese mountain dog was presented in a semi-comatose state. Based on serum hypo-osmolality with inappropriate urine hyper-osmolality and urine sodium excretion, the dog was diagnosed with a syndrome of inappropriate antidiuretic hormone secretion secondary to a histiocytic sarcoma. This report describes the first case of this syndrome in a dog with histiocytic sarcoma.