Effect of o,p'DDD therapy on endogenous ACTH concentrations in dogs with hypophysis-dependent hyperadrenocorticism.

The effect of o,p'DDD therapy on the endogenous plasma ACTH concentration was evaluated in 15 dogs with hypophysis-dependent hyperadrenocorticism. Adequate control of hyperadrenocorticism with o,p'DDD was based on the reduction of water consumption to within the normal range, disappearance of clinical signs of lethargy, weakness, alopecia, thin skin, or pendulous abdomen, and an increase in blood cortisol below the normal range after exogenous ACTH administration. Endogenous ACTH concentrations were determined for each dog after the disease was controlled and while they were given o,p'DDD on a maintenance schedule. Endogenous ACTH concentrations increased in 14 of 15 dogs after o,p'DDD therapy, indicating a lack of suppressive effects of o,p'DDD on hypophysis ACTH secreting cells.