Androstenone induces horses to be more compliant with human–horse interactions

Olfactory signals play an essential role in communication in animals. Pheromones are volatile or nonvolatile chemicals that trigger social responses among animals. Therefore, pheromone treatment could, in theory, be used to modify horse behavior to improve human–horse relationships. Androstenone (5α-androst-16-en-3-one) is a steroidal pheromone found in the saliva of boars and elicits responses across species. However, its role in horse behaviors is not elucidated. This study investigated the effect of androstenone on horse behavior. Trainability (lowering head and moving hindfeet) and calmness tests (standing still with or without a stimulator) were performed with or without applying androstenone diluted with jojoba oil. Treatment with 10 μg/mL of androstenone applied 30 minute before the tests significantly decreased the time for the horses to lower their head compared with the control. The results of the calmness tests had no significant differences compared with the control group. In the pressure mediation test for trainability assessment, a group of horses treated with 10 μg/mL of androstenone moved their hind feet in a significantly shorter time (P < 0.05) than the control group. As a result, androstenone appears to induce horses to be more accepting of general management and training.