Deslorelin subcutaneous implants in Oryx dammah males for reproductive control

Abstract

The aim of this study was to assess the effects of the deslorelin subcutaneous implant as a temporary contraceptive method in the Oryx dammah male. For this purpose, deslorelin at different doses, i.e. 14.1 mg and 9.4 mg, was subcutaneously implanted in three males (Phase 1) and one male (Phase 2) adult Oryx dammah, respectively. Quantitative behavior evaluation and androgen concentrations in feces and plasma were assessed before and after implant application. Fecal androgen concentrations observed in treated males were compared with those measured in one orchiectomized male and two females. Fecal androgen concentrations increased up to 15 days after the implant application, then progressively decreased, reaching the basal level at day150 in Phase 1. In Phase 2, levels remained high until day 60 and returned to basal level on day 120. Plasma testosterone concentration was higher on the day of implant application than three months later, but with variable ranges among males. A general increase of activity levels and hierarchical changes were observed after treatment, in accordance with hormonal variations. Despite males cohabiting with two fertile females during the observation period, no births were recorded. However, between the end of Phase 1 and the beginning of Phase 2, i.e. about 10–11 months after the first deslorelin implant, a fertile mating occurred leading to the birth of a calf. Therefore, we can hypothesize a contraceptive effect up to 10 months after the implant. Testicular histology performed on one male at the end of the Phase 2 showed no spermatogenetic activity.Our results suggest that deslorelin implant can be used to temporarily control reproduction in the Oryx dammah male. Behavior and fecal androgen measurements were useful and repeatable, non-invasive methods to monitor response.