Canine Endogenous Oxytocin Responses to Dog-Walking and Affiliative Human–Dog Interactions

SIMPLE SUMMARY: It is widely recognized that humans and dogs share a unique relationship. However, the biological mechanisms that may contribute to this bond between owners and their pet dogs are still unclear. As such, we measured the concentration of oxytocin, a hormone that is important in social bonding, in dogs before and after two different activities: dog-walking and human–dog interactions. We also investigated whether the strength of an owner’s attachment to their dog affected the dog’s oxytocin concentration. Contradicting our suppositions, the experiment showed that the concentration of dog oxytocin was not substantially different following either dog-walking or human–dog interactions. Additionally, the strength of the human–dog bond did not affect oxytocin concentrations. We suggest that more research is needed to fully understand the role of oxytocin in human–dog bonding. ABSTRACT: Several studies suggest human–dog interactions elicit a positive effect on canine oxytocin concentrations. However, empirical investigations are scant and the joint influence of human–dog interaction and physical activity remains unexplored. The aims of the current study were to (a) examine the canine endogenous oxytocin response to owner-led dog-walking and affiliative human–dog interactions and (b) investigate the moderating effect of the owner-reported strength of the human–dog bond on such responses. Twenty-six dogs took part in a random order cross-over trial, involving dog-walking and human–dog interactions. Urinary samples were collected before and after each condition. The data were analyzed using linear mixed models with condition, order of conditions, condition duration, and latency from initiation of condition to urine sample collection considered as fixed effects, and the participant was considered a random effect. Canine urinary oxytocin concentrations did not differ significantly following dog-walking (mean change: −14.66 pg/mg Cr; 95% CI: −47.22, 17.90) or affiliative human–dog interactions (mean change: 6.94 pg/mg Cr; 95% CI: −26.99, 40.87). The reported strength of the human–dog bond did not significantly moderate the canine oxytocin response to either experimental condition. Contrary to our hypothesis, we did not observe evidence for a positive oxytocin response to dog-walking or human–dog interactions.