Observations on the Use of the GnRH Vaccine Gonacon™ in Male White-Tailed Deer (\u3ci\u3eOdocoileus virginianus\u3c/i\u3e)

Observations made over an 11 year period during the development and evaluation of the GnRH vaccine GonaCon™ use in male white-tailed deer (Odocoileus virginianus) are summarized. Sexually mature bucks at the Penn State Deer Research Center were administered a single immunization of GonaCon™ in July. Some males were also given a second boost immunization in September. Compared to similar aged controls, testicular size for treated males was considerably reduced in the first and subsequent years of study, as were testosterone concentrations and sexual libido. During the first year, antler development was relatively normal leading to antler hardening, although shedding occurred early. However, in subsequent years, antlers were generally smaller, remained in velvet throughout the winter, and froze and then broke off. Most males given the single immunization returned to breeding condition in 2-3 years, although they tended to be smaller than similar-aged males. Males given the two immunizations tended to remain in a treated state longer. Treated males that died during the study had a higher incidence of pulmonary disease than non-treated males. We conclude that while GonaCon™ reduces the reproductive capacity of male white-tailed deer, the negative effects on health and antler development make it impractical for field application with bucks