Abstract
Effects of haloperidol on the breast were investigated histologically and hormonally in female dogs at each stage of estrous cycle. In immature-period, metestrus and anestrus, female dogs were treated orally with 3 mg/kg/day of haloperidol for 5 weeks. The levels of progesterone and prolactin in serum were determined frequently during the pre-dosing and dosing period. After the dosing period, the animals were autopsied and the mammary glands were examined microscopically. Levels of serum prolactin increased by administration of haloperidol at every stage of estrous cycle. Levels of serum progesterone were high in metestrus and were low in immature-period and anestrus. In metestrus, swelling of the breast, lactation, and prominent hyperplasia of mammary glands were observed. In immature-period, mammary glands and ducts were not observed. In anestrus, the mammary glands reduced in size and the mammary ducts became dilated. Thus the mammary change should be due to the difference of hormonal environment, especially levels of progesterone and prolactin, and this difference of hormonal environment was caused by administration of haloperidol or estrous cycle in each animal.
