Adrenal Cortical Insufficiency in Young Chickens Exposed to a High Ambient Temperature

Abstract

The adrenal cortical response to an acute heating episode was studied in broiler cockerels which were heated (43 C) in chambers for periods up to 2 hr in duration. At intervals of 30 min birds were removed randomly from the chambers, bled via cardiac stab, killed by cervical dislocation, and the adrenals were dissected and frozen. It appeared that acute heating caused acute adrenal cortical insufficiency (AACI) to develop. The development of AACI in heat stressed broiler cockerels was characterized by a sharp increase in levels of plasma corticosteroids which was followed by a rapid decline. The decline of plasma corticosteroid levels was associated with the significant reduction of adrenal cortical levels of the corticosteroids. There was a concurrent decline in plasma levels of glucose, sodium/potassium ratio, total calcium, and inorganic phosphate. These findings conformed to the description of AACI in humans suffering from Addison’s disease. The loss of corticosteroids from the adrenal gland was not related to loss of their precursor cholesterol. The development of AACI in heat stressed chickens may predispose them to irreversible heat prostration and death due to cardiovascular failure.