Renal tubular acidosis in horses (1980-1999)

Renal tubular acidosis (RTA) is characterized by altered renal tubular func tion resulting in hyperchloremic metabolic acidosis. The purpose of the stu dy was to describe RTA in 16 horses. No breed or sex predilection was found . The mean age at onset of the disease was 7 years of age. The type of diet had no apparent effect on development of RTA. The most common clinical sig ns were depression. poor performance, weight loss, and anorexia. Initial bl ood work revealed a marked hyperchloremic metabolic acidosis in all horses and a compensatory respiratory response in most horses. Sixty-three percent (10/16) of the horses had some evidence of renal damage or disease. Initia l treatment consisted of large amounts of sodium bicarbonate given intraven ously and orally for the prompt correction of the acidosis. Response to tre atment was largely dependent on the rate of sodium bicarbonate administrati on. Long-term oral supplementation with NaHCO3 was required for the mainten ance of normal acid-base status in individual horses. Recurrence of RTA was noted in 56% (9/16) of the horses. Horses with evidence of renal disease h ad multiple relapses. RTA should be considered as a differential diagnosis in horses with vague signs of depression, weight loss, and anorexia. The pa thogenesis of RTA in horses remains uncertain. but prompt recognition and e arly aggressive intravenous sodium bicarbonate therapy followed by long-ter m oral supplementation seem to be important to successful management.