Investigation on the aldosterone concentration before and after ACTH application in 44 dogs with hypoadrenocorticism

It was the objective of this retrospective study to evaluate the aldosterone concentrations in 44 dogs with hypoadrenocorticism. Additionally, an overview is given over the main clinical findings and laboratory abnormalities associated with this condition. The general condition was moderately to severely altered in 40 of the dogs. The most frequently encountered clinical signs were anorexia, vomiting, diarrhoea, weight loss, and polyuria/polydipsia. Bradycardia was detected in 12 dogs. Hyponatremia was found in 43 and hyperkalemia in 39 dogs. Other findings were azotemia, hyperphosphatemia, hypercalcemia, hypoglycemia and anemia. Aldosterone concentrations before and after ACTH application were significantly lower than in healthy dogs. No relationship was detected between potassium and aldosterone concentrations. This means that there are mechanisms which, under certain circumstances, allow the maintenance of a normal potassium balance without aldosterone. The study shows that the measurement of aldosterone before and after ACTH application is of limited value for the assessment of the function of the zona glomerulosa.