Administering GonaConTM to white-tailed deer via hand-injection versus syringe-dart

Immunocontraceptive vaccines have shown some promise for fertility control of white-tailed deer (Odocoileus virginianus) in urban and suburban habitats where traditional methods of population control may not be applicable. Currently, the only contraceptive vaccine approved by the U.S. Environmental Protection Agency for use in white-tailed deer is GonaConTM Immunocontraceptive Vaccine, but it is registered for use via hand-injection only. It has been suggested that remote-delivery of immunocontraceptives would be more cost-effective than hand-injection, but there is the potential for incomplete injection from a syringe-dart. Therefore, the purpose of our research was to: (1) conduct a dart configuration assessment trial to determine the ideal syringe-dart configuration for remote-delivery of GonaCon to white-tailed deer and (2) use the determined syringe-dart configuration in a subsequent trial to evaluate the vaccine efficacy when administered to female white-tailed deer via hand-injection versus syringe-dart. We saw comparable results with regard to vaccine dispersal during the dart configuration assessment and the efficacy trial; syringedart injected deer presented vaccine deposits and reaction sites both subcutaneously and intramuscularly, whereas, hand-injected deer presented vaccine deposits and reaction sites only intramuscularly. One year after administration, 4 of 5 deer treated with syringe-darts were pregnant, compared to 3 of 6 deer that received hand-injections. Anti-GnRH titers were negatively related to pregnancy status. We did not observe a high level of vaccine efficacy with the syringe-dart delivery method we used. Therefore, we recommend further research of syringe-dart delivery of GonaCon with a larger sample size where the vaccine is deployed in a single bolus similar to a hand-injected presentation.