Abstract
Few reports appear in the literature on maintenance therapy in ruminants following bilateral adrenalectomy. Differences in hormone administration routes, criteria, species and environmental conditions probably account for the different dose levels that are reported. Cowie and Stewart(1) and Cowie and Tindal(2) reported that daily absorption from implanted tablets of 6–12 mg cortisone and 2.5 mg desoxycorticosterone acetate (DCA) is sufficient for maintenance of lactation in the adrenalectomized goat. Goding and Denton(3) were able to maintain adrenalectomized sheep on daily intramuscular injections of 25 mg cortisone and 5–10 mg DCA. Estergreen and Van Demark(4) reported that 25 mg of cortisone and 5 mg DCA per 100 lb body weight per day would successfully maintain adrenalectomized calves.
Materials and methods. To evaluate properly the minimal maintenance levels of adrenal steroids required in the bilaterally adrenalectomized animal, environmental and physiological stress should be reduced to a minimum.
The animals used in this study were 3 year old female goats of a mixed dairy type breed. Adrenalectomized and intact control animals were housed in separate pens in a controlled environment chamber. A temperature of 25°C ± 0.5°C, relative humidity of 50 ± 2% and alternating 12 hours of light and darkness were maintained throughout the study, thus minimizing environmental stress.
Bilateral adrenalectomy was performed in two stages. The first stage was removal of the right adrenal gland. After a 3 week interval the second stage, removal of the left adrenal, was performed.
Adrenalectomy in the goat is complicated by the absence of adrenal veins. The right adrenal is securely attached to the vena cava and the left adrenal gland is firmly attached to the renal vein near its junction with the vena cava. Previous investigators(1, 2) reported the use of special clamps which were applied between the gland and the vessel wall.
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