Effects of Social Pairing on Measurable Disease Outcomes in Hospitalized Rhesus Macaques ( <i>Macaca mulatta</i> )

Rhesus macaques (Macaca mulatta) living in outdoor breeding colonies may require transient housing in an indoor hospital setting. While previous studies have documented the benefits of socially housing macaques to promote psychosocial wellbeing, concerns of pathogen transmission or wound tampering may influence pairing decisions during clinical treatment. The aim of the present study was to determine whether paired social housing during hospitalization affects 1) length of treatment time, 2) incidence of hospital-acquired diarrhea, and 3) enteric pathogen transmission. We hypothesized that there would be no significant differences in the length of treatment time, incidence of hospital-acquired diarrhea, or change in the number of enteric pathogens between paired and unpaired groups. The first study population was a retrospective data set comprising 591 animals (105 paired, 486 unpaired) presenting with digit injuries over a 6.5-year period. The second study population was a prospective set of 40 animals enrolled upon presentation to the nonhuman primate colony hospital. Analyses showed no significant differences in the length of treatment time, incidence of hospital-acquired diarrhea, nor change in the number of enteric pathogens detected in stool samples collected on Days 0 and 7 associated with pairing status. These findings support our hypotheses, and we conclude that this study provides no evidence to support using concerns of prolonged treatment times, hospital-acquired diarrhea, and enteric pathogen transmission between conspecifics to limit social housing in a hospital setting. Therefore, we recommend that clinical and behavioral teams work together to advocate for social housing of clinically ill or injured patients.