Aqueous vasopressin response test in clinically normal dogs undergoing water diuresis: technique and results

Studies were undertaken to develop a standard procedure and to establish reference values for an aqueous vasopressin response test in dogs with normal renal function undergoing water diuresis. After IV administration of 5 mU of aqueous antidiuretic hormone (ADH)/0.45 kg of body weight of 13 water-loaded clinically normal dogs, the mean urine specific gravity increased from 1.002 +/- 0.001 to 1.021 +/- 0.0058; the mean urine osmolality increased form 99 +/- 52 mOsm/kg of water to 933 +/- 252 mOsm/kg. The PCV, total plasma protein concentrations, and serum osmolalities decreased in all dogs during water loading and ADH administration, but slowly returned toward base-line values after discontinuing the ADH infusion.