Meeting Abstract
Effective contraception plays a critical role in collection plans for zoo species. Permanent methods to control reproduction often are not suitable options, and short-term contraceptive efforts (e.g., synthetic progestins) have proved challenging. A promising alternative method for use in both sexes is a gonadotropin-releasing hormone (GnRH) immunocontraceptive vaccine. This vaccine has been used successfully for population control in a variety of wild and domestic mammalian species. We tested the efficacy of the GnRH vaccine GonaConTM: USDA in Nile hippopotamuses, (n=2♀, 1♂) or Improvest®: Zoetis US in red river hogs (n=2♀), large flying foxes (n=12♂), Nubian goat (n=1♀), warthogs (n=2♀), and reticulated giraffe (n=1♀). Animals were injected subcutaneously 1-3 times with the vaccine using empirical doses. Serial injections were separated by at least four weeks. Before and after vaccine administration, we measured fecal testosterone and progesterone in males and females, respectively, using enzyme immunoassays. Results were highly variable depending on species and/or course of treatment. For example, treatment was effective in all species tested with the exception of warthogs and giraffe. Bats were suppressed but had negative vaccine reactions following a single injection of the vaccine. All other species required multiple doses to suppress patterns of gonadal steroids. GnRH vaccines have potential for contraceptive treatment in zoo mammals. Health and hormone monitoring, however, is needed in species previously untested to assess safety, efficacy, reversibility, and the need for booster injections.
