You’ve probably heard of the hormone/neurotransmitter oxytocin. Its role in childbirth (where it often goes by the medicine’s trade name Pitocin) is well known, but researchers continue to uncover new details about how it effects social interactions, particularly with regards to the formation of interpersonal bonds.

 

Most of these studies involve members of the same species. That more or less immediate bond that many mothers feel for their newborn babies is due in large part to oxytocin. The molecule has been shown to improve social memory between mice and face recognition in people, which only makes sense when you think of its role in social bonding. Animals certainly don’t want to make mistakes when it comes to which individuals they become emotionally attached to.

But now it is starting to look like oxytocin plays a role in the bond that owners and their dogs have for each another. In one study, 55 owner-dog pairs underwent a series of experiments that investigated whether or not the length of time a dog gazed into his or her owner’s eyes affected the owner’s oxytocin levels. The answer is “yes.” To paraphrase the paper:

The participants were divided into two groups according to the degree of their relationship with their dog and the duration of the dog’s gaze. The group of owners who received dog’s gazes over a longer duration had a better relationship with their dogs, and showed a higher concentration of urinary oxytocin than the group who received dog gazes of short duration. These results show that the level of oxytocin in humans may be related to attachment behavior, and urinary oxytocin could be used as a non-invasive psychoneuroendocrinological indicator of the relationship between humans and dogs.

A different study looked at whole range of physiological and biochemical parameters in owners and their dogs before and after a 30 minute session during which owners petted, talked to, and generally fawned all over their dogs. The results were pretty astounding. Concentrations of oxytocin, beta-endorphin, prolactin, beta-phenylethylamine, and dopamine increased in both dogs and people after just 30 minutes of positive interaction.

I find it fascinating that dogs and people have developed such a close, social relationship with each other that something as simple as looking into one another’s eyes can alter our biochemistry. When I think back to the relationship that I had with the “dog-of-my-life,” Owen, one aspect that really stands out is the way he used to stare at me. He would lie with his head on his paws and his chocolate brown eyes simply wouldn’t leave mine (until it was time for a snooze or treat, at least). Based on this research, I bet the two of us were awash in oxytocin and other “pro-social” hormones and neurotransmitters during those times, which would go a long ways towards explaining our special relationship.

Dr. Jennifer Coates

References

Dog's gaze at its owner increases owner's urinary oxytocin during social interaction. Nagasawa M, Kikusui T, Onaka T, Ohta M. Horm Behav. 2009 Mar;55(3):434-41.

Neurophysiological correlates of affiliative behaviour between humans and dogs. Odendaal JS, Meintjes RA. Vet J. 2003 May;165(3):296-301.

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