Investigation of the efficacy of the GnRH agonist deslorelin in mitigating intraspecific aggression in captive male Amur leopards (Panthera pardus orientalis).

Housing bachelor groups is a necessary aspect of the care and husbandry of non-breeding individuals in zoological collections. Intraspecific aggressive behaviors may occur in this setting despite management strategies designed to mitigate these behaviors. Androgens (including testosterone) are associated with aggression in male species and interventional techniques to alter the animals' physiology to modify aggressive behavior are sometimes required. When agonistic behavior and physical aggression in two mature male Amur leopards housed together at Tayto Park escalated, despite all strategic management involvements, further intervention to moderate aggression was required. The gonadotropin-releasing hormone (GnRH) agonist, deslorelin, has been found to be effective in reducing androgens in domestic and non-domestic carnivores. We hypothesized that deslorelin's suppressive effect on hypothalamic-pituitary-gonadal axis would mitigate intraspecific aggression in two male intact leopards. Behavioral observations were carried out pre- and post-implant implantation of 9.4 mg deslorelin implant. The frequency of agonistic/aggressive behaviors for both leopards declined significantly (p < 0.05), as did marking behaviors post-implantation (p < 0.001). The insertion of deslorelin implants in two male intact leopards demonstrating increased frequency and severity of aggressive behaviors resulted in a reduction of the frequency of these behaviors. Deslorelin implantation should be considered for management of interspecific aggression of intact male leopards in bachelor groups.