Trio housing of adult male rhesus macaques (Macaca mulatta): Methodology and outcome predictors

Background This study evaluated the feasibility of trio housing caged adult male rhesus macaques and attempted to identify outcome predictors for trio housing formation and its intermediary introduction steps. Methods Subjects were familiarized consecutively to each potential group member via protected contact prior to introduction into the trio. Seven trios were attempted, involving 18 males, with three males attempted in two different trios. Results One group was deemed successful, with a tenure of 51 days. Five were disbanded within minutes, and one was deemed unsuccessful the following morning. Two males sustained wounds requiring veterinary care over the course of the study. Outcome of the protected contact phase was predicted by age and temperament disparities as well as initial behavior. Conclusions While outcomes were poor, it suggests that attempts can be made relatively safely, and alternative introduction strategies should be explored to increase the feasibility of trio housing for adult males.