Contraception for population control in exotic carnivores.

There is an increasing demand for management of feral and wild carnivores; since many of them have become "pest species" by adapting successfully to changing environments, having substantial impacts on their prey species, and serving as reservoirs for infectious diseases. Also in captivity, a low adult mortality and an increase in longevity, especially in large carnivores, cause an urgent need for population management. This paper presents an overview on contraceptive strategies to control reproduction in carnivores. Factors that have to be considered before applying a certain method for fertility suppression are discussed. For birth control, several methods of hormonal chemosterilization, immunocontraception and pregnancy termination have been developed in domestic and captive exotic carnivores, but none of them are yet suitable for free-ranging animals. GnRH agonists, which suppress pituitary function very efficiently, are recommended in captive and domestic animals for reversible contraception. Immunological contraception, causing prolonged infertility after single application, is a promising approach for feral animals. However, a specific gamete or hormone-derived "self" antigen must be identified for each particular species.