Expert Voices

Dog Kisses are More Than Just Slobber (Op-Ed)

bassett hound, long stare
In the Dognition database, 32 percent of dogs had a "long gaze." (Image credit: Dognition.)

Brian Hare is an associate professor and Vanessa Woods is a research scientist in evolutionary anthropology at Duke University. They founded Dognition, a Web-based service that helps people find the genius in their dogs. This post was adapted from their New York Times' best-seller "The Genius of Dogs." They contributed this article to LiveScience's Expert Voices: Op-Ed & Insights.

There is real chemistry between dogs and their owners, new research over the last few years and data from Dognition show. From a simple kiss to a long, loving gaze, everyday interactions with dogs are responsible for changing people's biochemistry for the better.

Oxytocin is a peculiar little molecule. It is known as the "hug hormone" because it is what makes you feel good when you are touched by a loved one, get a massage or enjoy a good meal. Oxytocin also has pain-relieving properties and can decrease stress and blood pressure.

People experience oxytocin in many social relationships, including bonding with children or partners. What is surprising is that people would also experience a change in this hormone when bonding with a completely different species.

Friends with benefits

Miho Nagasawa of Azabu University in Japan and colleagues conducted a study with 55 dogs and their owners. People whose dogs gazed at them for two minutes or longer (23 percent of dogs) showed a higher increase in oxytocin than people whose dogs gazed at them for less time. People with dogs with a long gaze also reported being happier with their dogs than those people whose dog's gaze was only around a minute long.

These results were echoed in the database of Dognition, a Web-based service that helps owners find the genius in their dog. In a sample of 276 dogs, 32 percent of dogs had a long gaze (a continuous 90 seconds or more) in one or more trials. (To see if your dog has a long gaze, try the Dognition eye contact game.)

In another study by Linda Handlin and colleagues from the University of Skövde in Sweden, owners who kissed their dogs the most frequently had higher levels of oxytocin than other owners.

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Handlin found that along with kissing, there were two other factors that predicted the higher levels of oxytocin — the first was that the owners were more likely to perceive their relationship with their dog as pleasurable (i.e., they did not think that looking after their dog was difficult or a chore). The second was a lower frequency in giving treats, showing that the path to true love is not necessarily through a dog's stomach.

In a separate study by Johannes Odendaal and colleagues from the University of Pretoria in South Africa, owners were brought into a room that was empty except for two tables and chairs. The owners sat on a rug on the floor with their dogs and a nurse drew their blood. For the next 30 minutes, each owner's attention was completely focused on his or her dog. They talked softly to their dogs, stroked them gently and scratched their bodies and behind their ears. The participants' blood was drawn again after 30 minutes.

The researchers found that participants' blood pressure decreased, and they experienced an increase in not only oxytocin, but also a whole other range of hormones, including beta-endorphins, which are associated with euphoria and pain relief; prolactin, which promotes bonding associated with parenting behavior; phenylethylamine, which tends to increase when people find a romantic partner; and dopamine, which increases pleasurable sensations.

When each dog owner came in and read a book for 30 minutes, oxytocin and the other hormones did not increase as much as they did during interactions with their dog. What is even more incredible is that not only did humans experience a rise in these hormones — the dogs did, too. It seems the feelings of bonding and affiliation are entirely mutual.

Humanity's relationship with dogs is so extraordinary that it affects humans' very biochemistry. Science is only beginning to understand the mechanisms of this relationship, and the implications will keep cognitive psychologists busy for many years to come. But for those who just need a little something to lift their spirits, try a meaningful gaze, or even a kiss, with your best friend.

Woods' most recent Op-Ed was "Does a Dog's Breed Really Dictate Its Behavior?" The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science.