Effect of deslorelin implants on the testicular function in male ring- tailed lemurs (Lemur catta)

Ring-tailed lemurs (Lemur catta) are popular exhibit animals in zoos. During the breeding season, males may fight and this can result in serious wounds and/or escapes. The hormonal contraceptive deslorelin, a GnRH-agonist, has been used in different species to suppress reproduction. This contraceptive strategy can reduce the production of sexual hormones and, therefore, could be used to control aggressive behaviour. Here, we analysed the effect of a 4.7 mg deslorelin implant on testicular function in five male ring-tailed lemurs. The aim of the study was to assess if this contraceptive strategy could be used to reduce testosterone levels and thus aggressive interactions between individuals. Neither testosterone concentrations detected in faeces nor spermatogenesis evaluated by testes histology was suppressed by the deslorelin treatment. These results suggest that a GnRH implant containing 4.7 mg deslorelin has no contraceptive effect in ring-tailed lemurs. The effect of the use of different dosages of deslorelin implants, as well as that of other hormonal contraceptives, should be evaluated in this species.