Renal Tubular Acidosis in Horses

Type 1 renal tubular acidosis (RTA) is a sporadic disorder in horses. The RTA may be preceded by drug therapy for another condition or renal injury, or there may be no predisposing cause. RTA may be transient or recurring. Genetic predisposition is unproved but possible in some cases.

Signs include acute onset of depresson, anorexia, muscle trembling, and tachycardia and/or arrhythmia. There are many differential diagnoses for these clinical signs, so serum chemistry testing and urinalysis are necessary. There is a severe metabolic acidosis, marked hyperchloremia, and hypokalemia with equine RTA. The urine pH is neutral to alkaline.

Administration of sodium bicarbonate IV and PO is generally successful in correcting the metabolic acidosis. Potassium supplementation may be critical if the serum potassium concentration is <2.5 mEq/L or if the horse is trembling or has cardiac arrhythmias. Treatment throughout a few days may result in complete resolution in some horses, but others may require continued supplementation with sodium bicarbonate administered PO.