POLYGLANDULAR DEFICIENCY SYNDROME IN A BOXER DOG - THYROID-HORMONE AND GLUCOCORTICOID DEFICIENCY

Primary hypothyroidism and partial primary adrenocortical deficiency ( isolated glucocorticoid deficiency) were diagnosed in an 8-year-old sp ayed female boxer dog, presented because of progressive symmetrical tr uncal alopecia, lethargy, and intolerance to cold. The diagnosis was b ased upon the combination of low, non-TSH-responsive concentrations of plasma thyroxine and low urinary excretion of corticoids together wit h high plasma concentrations of ACTH. Normal suppressibility of ACTH c oncentrations by a low dose of dexamethasone indicated an intact feedb ack system. Plasma growth hormone levels were elevated, most probably because somatostatin release was depressed by the glucocorticoid defic iency. The dog improved during oral replacement therapy with thyroxine until death ensued after 9 months as a result of intercurrent disease . Autopsy revealed thyroid atrophy and lymphocytic adrenalitis with co mplete destruction of the zona fasciculata and zona reticularis of the adrenal cortex. The combination of primary hypothyroidism and primary adrenocortical deficiency in this dog is identical to the entity know n as type II polyglandular autoimmunity or Schmidt's syndrome in human s. The adrenocortical insufficiency remained confined to glucocorticoi d deficiency during the observation period; on no occasion did electro lyte concentrations in the plasma reach values suggestive of mineraloc orticoid deficiency.