Progestagens are reproductive hormones like ones that are used in birth control for women. Progestagens are a form of the natural progesterone produced in the body. Various forms of progestagens with different routes of administration have been used for estrus (heat) synchronization. It can be used to extend the lifespan of the corpus luteum during the breeding season when goats are already cycling and it is required for getting goats to show estrus and breed in the non-breeding season. Although not approved for use in the U.S., in research, the intravaginal sponge has been the treatment of choice for estrus synchronization as well as for out-of-season breeding in goats. These sponges inserted into the vagina usually contain about 45 to 60 milligrams of a synthetic progesterone (progestagen) and are left in place for 8 to 19 days. The most common progestagen used in sponges are fluorogestone acetate (FGA; Cronogest 45) and methyl acetoxy progesterone(MAP; Repromap and Veramix). For the most success, sponges are widely used either in conjunction with pregnant mare serum gonadotropin (PMSG), FSH or prostaglandin to more tightly synchronize and/or cause a superovulatory response in which many eggs are released (for embryo transfer work for example). However, under research conditions, sponges impregnated with natural progesterone in higher doses (400-500 mg) have been used and synchrony and fertility similar to that of commercial sponges were achieved. An alternative means of supplying continuous, exogenous progesterone is a controlled internal drug-releasing device (CIDR). This product is in the form of a silicone intravaginal progesterone insert. Administration is similar to that of intravaginal sponges and can be used in conjunction with any of the gonadotropins or prostaglandin listed above. Similar success rates have been obtained with CIDRs and sponges. Use of any drug not labeled for goats should be done only in consultation with your veterinarian.
For additional reading on other methods of estrus synchronization, please visit: http://www.extension.org/pages/19331/goat-reproduction-estrous-synchronization
References: Whitley, N.C. and D. J. Jackson. 2004. An update on estrus synchronization in goats: a minor species. J. Anim. Sci. 82: E270-276E (Proceedings).