A Method of Adrenalectomy in Sheep

The adrenalectomized animal is of significance as an experimental animal in elucidating the role of glucocorticoids in regulatory mechanisms for glucose metabolism in ruminants. The methods of adrenalectomy, including the surgical procedure, postoperative management, longer prognosis and completeness of adrenalectomy tests, are discussed from our experiments on 30 cases of sheep adrenalectomized. The results are as follows. 1) Bilateral adrenalectomy was performed in double-stage operations, allowing 7 to 14 days for recovery between operations. 2) The surgical approach to the adrenal glands which was adopted was the posterior method. 3) Of the 30 wethers adrenalectomized, five died as a direct result of surgery. 4) In the postoperative management, procaine penicillin-G and sulfa medicine were administrated as chemotherapy for bacterial infections. After the removal of the second adrenal gland, deoxycorticosterone acetate (DOCA) and cortisol acetate were also used as the hormone replacement therapy in addition to the above therapy. 5) Body temperatures which increased after the operation returned to the normal level about one week later and the adrenalectomized animals had gained a good appetite during the period. Both the serum Na/K ratio and the plasma glucose level were maintained at a certain value after bilateral adrenalectomy. 6) In order to prolong the lifespan of some animals, a few times more than the usual maintenance dose of DOCA (5mg/head/day) was re-quired. 2) When the plasma cortisol concentrations were determined by the RIA method in the 23 animals who had survived over 2 months after bilateral adrenalectomy, the levels in 8 animals were relatively high, i. e., higher than 1.0ng/ml, and indeed in two of them the levels increased twofold over the controls after ACTH injection. It seems that some adrenal tissue remained after the operation and/or it was regenerated later with resultant cortisol secretion. These ob-servations show that we can successfully perform adrenalectomy on sheep by using our surgical procedure. It is recommended that the adrenalectomized sheep should be evaluated before they are used for experiments, based on highly sensitive methods of determining the plasma cortisol level.