Induced Termination of Pregnancy in Domestic Farm Animals

Abstract

Induced abortion may be desired during a normal or abnormal pregnancy. The methods of induced abortion differ between species mainly because of different sources for progesterone production during pregnancy between species and within a species according to different stages of gestation. In cows and buffaloes, pregnancy can be effectively terminated from 5 to 150 days by administration of luteolytic doses of prostaglandin F₂ alpha (PG). From 150 days onwards and till term bovine and bubaline pregnancies can be safely terminated by administration of a combination of PG and dexamethasone. During the last month of pregnancy in these two species, pregnancy can be successfully terminated by using either a PG or dexamethasone. In goats pregnancy can be terminated during the entire gestation by administration of luteolytic doses of prostaglandins. In sheep pregnancies up to 55 days can be terminated by administration of 100 µg cloprostenol or 10-12 mg of dinoprost. From day 55 onward the termination of sheep pregnancies requires the administration of single or multiple injections of dexamethasone. Early pregnancy (day 5-34) termination in the mare can be achieved by physical methods or administration of PG. The same treatment is effective in terminating pregnancies between day 35-120 but repeated injections are required and because the endometrial cups continue to exist for a couple of days after pregnancy termination, mares do not return to estrus for prolonged periods. The termination of equine pregnancy after 4 months is difficult till term. The results of administration of PG or corticosteroids is suboptimal and manual disruption of the fetus after dilation of the cervix with PGE₂ creams is more reliable method of pregnancy termination.