GnRH Immunocontraception of Male and Female White-Tailed Deer Fawns

Immunocontraceptive vaccines based on gonadotropin-releasing hormone (GnRH) have been tested in adult white-tailed deer (Odocoileus virginianus), but their effects on fawns are unknown. The purpose of this study was to determine if early immunization against GnRH would induce a long-lasting immune response in fawns, and if it would delay or prevent sexual development. We gave primary and subsequent booster injections of a KLH-GnRH/Freund’s vaccine to 6 male and 6 female fawns. This vaccine contained the same active ingredients as GonaCon™ vaccine, but it contained Freund’s adjuvant instead of AdjuVac™ adjuvant. Two 450-μg injections were given 1 month apart when fawns were 3 and 4 months of age. Although 1 female fawn produced a multiyear contraceptive response similar to that observed previously in vaccinated adults, the immune response lasted only 1 year in the other 11 fawns. Antibody titers in those 11 fawns declined sharply to near zero during the second and third years after vaccination. Our results indicate that treating 3- to 4-month-old white-tailed deer with the GnRH vaccine did not induce contraception or sterilization, and it did not delay or prevent sexual development. No adverse health effects were apparent in GnRH-treated fawns.