A new study, conducted by researchers at Tokyo University, has demonstrated that administering the hormone oxytocin to dogs promotes social behaviors toward both other dogs and human partners. The report, which has been published in the journal Proceedings of the National Academy of Sciences of the United States of America, adds to the growing body of evidence that suggests oxytocin is a major player in encouraging the sociality of mammals.   

Oxytocin (OT), which has also been dubbed the “cuddle chemical” or “trust hormone”, is a neurotransmitter synthesized in the hypothalamus and secreted by the pituitary gland. OT is known to have numerous different biological roles, such as the facilitation of birth and labor, but researchers have become increasingly interested in this hormone in recent years because of its apparent effects on behavior. In particular, studies have highlighted a role for OT in social bonding. However, previous investigations have mainly focused on monogamous mammals and bonding in reproductive contexts.

In order to fill in some gaps in this field of research, Tokyo University scientists turned to the domestic dog. Dogs were an ideal subject for investigation because they are social animals that often form strong bonds with human partners.

For the study, the team recruited 16 pet dogs and administered a nasal spray that either contained OT or a placebo (saline). They then took blood and urine samples at regular intervals whilst monitoring how the dogs interacted with both their owners and other dogs.

The team observed that when dogs were administered with exogenous OT, they displayed more social and affiliative behaviors toward both their owners and other dogs when compared with the placebo. These behaviors, which included sniffing, licking, playing and prolonged eye contact, were indicative of bonding. Furthermore, they found that exchanging positive social behaviors with partners also triggered the release of endogenous OT.

Taken together, these data not only suggest that OT is involved in the development of social relationships in dogs, but they also add to the growing consensus that OT plays pivotal roles in social bonding in mammalian species.