Oxytocin promotes social bonding in dogs

Abstract

Recent evidence suggests that enduring social bonds have fitness benefits. However, very little is known about the neural circuitry and neurochemistry underlying the formation and maintenance of stable social bonds outside reproductive contexts. Oxytocin (OT), a neuropeptide synthetized by the hypothalamus in mammals, regulates many complex forms of social behavior and cognition in both human and nonhuman animals. Animal research, however, has concentrated on monogamous mammals, and it remains unknown whether OT also modulates social bonds in nonreproductive contexts. In this study we provide behavioral evidence that exogenous OT promotes positive social behaviors in the domestic dog toward not only conspecifics but also human partners. Specifically, when sprayed with OT, dogs showed higher social orientation and affiliation toward their owners and higher affiliation and approach behaviors toward dog partners than when sprayed with placebo. Additionally, the exchange of socio-positive behaviors with dog partners triggered the release of endogenous OT, highlighting the involvement of OT in the development of social relationships in the domestic dog. These data provide new insight into the mechanisms that facilitate the maintenance of close social bonds beyond immediate reproductive interest or genetic ties and complement a growing body of evidence that identifies OT as one of the neurochemical foundations of sociality in mammalian species.

Keywords: cooperative bonds; cooperative mechanisms.

Fig. 1.

The effect of OT on dogs’ affiliative behaviors. Mean hourly rate (+SEM) of a combined measure of all affiliative behaviors that dogs directed to their owners (A) or dog partners (B). *P < 0.05.

Fig. 2.

OT effects on dogs’ tendency to approach their partners. Relation between the social approach index for OT (black) and saline (white) treatments and subject endogenous OT levels before experimental sessions. Lines represent the trend lines for OT (solid) and saline (dashed) datasets.

Fig. 3.

The effects of intranasal OT on parasympathetic cardiac control. “Prespray” corresponds to the 5-min interval before spray intake, “spray” to the 5-min interval right after spray intake, and “postspray” to the subsequent 5-min interval (i.e., 5–10 min). *P < 0.05 versus basal. Markers represent the mean HF HRV values (+SEM) for the OT (black) and saline (white) treatments.

Fig. 4.

Plasma kinetics of OT. Plasma OT concentrations (mean + SEM) at baseline (0 min) and every 15 min after intranasal delivery of OT (black) or saline (white) treatment. *P < 0.05 versus basal, Wilcoxon signed rank test.