Reproductive management is essential to meeting genetic and demographic goals, enriching the lives of animals and supporting the long-term sustainability of captive populations. Temporarily preventing breeding in some individuals is fundamental to successful population management. Contraception in zoo populations is used to prevent certain animals from breeding due to space limitations, the need to maintain the genetic diversity of the entire AZA population, and so that animals that should not be breeding with one another to stay in social groups to benefit their welfare.
Contraception Products & Guidelines
Click on the links below to view information on various contraception products or to view contraception guidelines for a particular taxonomic group. Not sure where to start? Explore our Choosing a Contraceptive and Contraception Decision Tree tools.
Birth Control Pills
Choosing the Appropriate Contraceptive Method
A variety of factors such as efficacy and safety of available methods, the animal's age, behavioral and social factors, the practicality of different delivery systems, and the individual's reproductive status must be considered when selecting an appropriate contraceptive method. It is unlikely that the same birth control method will be the most appropriate choice during all stages of an animal's life. Permanent sterilization or participation in contraceptive studies is encouraged for surplus animals.
Duration of Effect
Different contraceptives are designed to be effective for varying amounts of time. Thus, managers should consider how long the animal needs to be contracepted when choosing a contraceptive method. In addition to the method’s intended duration of effect, managers should also consider reversibility, particularly for animals which managers hope to breed after contraception.
Administration of oral contraceptives need only be stopped to initiate reversal. To hasten time to reversal, Suprelorin® and MGA implants can/should be removed. Reversal times for injectables, such as PZP vaccine and Depo-Provera, cannot be manipulated. Time to reversal varies for many reasons and reversal has many stages (e.g. resumption of cycling or sperm production, courtship behavior), up to and including successful production of offspring, which is how the RMC determines reversibility. Many factors other than contraceptives affect reversibility. These include reproductive history, age, health, body weight (very thin or obese animals may not ovulate or conceive) and, of course, fertility of the partner.
Method & Frequency of Delivery
Contraceptives range from orally ingested products, to injectables, to long-term implants and the method and frequency of delivery of the contraceptive may be a consideration. For example, oral ingestion may be an attractive option when available, but it does depend on compliance of the animal in taking the contraceptive on a regular basis (usually daily). Some implants are small and injectable via trocar, while others require a surgical incision.
Possible Side Effects
Contraceptive approaches that impact the reproductive system via a hormonal alteration are also likely to change behavior and will in some cases, impact secondary sexual characteristics. Whether this is an important consideration depends on the species and management scenario. Weight gain is also a common side effect of contraception. Another important consideration is whether the contraceptive is likely to impact lactation.
In addition to taxon-specific contraceptive recommendations and general contraceptive product overviews, the RMC has developed two contraception decision-making guidance tools: Choosing a Contraceptive and a Contraception Decision Tree tools. The at-a-glance tool provides a quick overview of contraceptive approaches and considerations, whereas the contraception decision tree is more useful for making contraception decisions for particular animal(s).