Contraception of zoo animals using Improvac® in German-speaking countries - A questionnaire survey

The aim of this study was to obtain an overview of applied contraceptive methods, with a special focus on the gonadotropin-releasing hormone (GnRH) vaccination with Improvac®, in animals in zoological institutions in German-speaking countries. A survey was prepared inquiring commonly vaccinated species, application intervals and booster vaccinations over the past 11 years and sent to 84 zoological facilities. The questionnaire was answered by the respective veterinarians of 21 zoos (response rate 25%). In the study period, the GnRH vaccine was used in 188 individuals of 42 mammalian species. Bovids were vaccinated the most frequently, followed by giraffes, equids and camelids. Application intervals varied widely between zoos and animal species. The most frequently cited reasons for contraception were population management and breeding exclusion on the recommendation of the EAZA Ex situ Programmes. Undesirable pregnancies during vaccination were observed in 17 individuals (12.1%). Three animals successfully produced offspring after cessation of GnRH vaccination. Most common side effects after the injections were a localised swelling, slight lameness and sexual hyperactivity in some male individuals. It can be concluded that contraception with Improvac® is common in zoological institutions, although no consistent vaccination scheme was identified for most species.