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My Dog Skip: Effects of Pet Ownership on Mental Health

Stuck at home, our furry friends are perhaps more important than ever.

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After several weeks of having to stay home, for many of us, there is an unsung hero that makes all of this a bit better: our pets.

For many, having pets is no small luxury. Between food, exercising, vet bills, and even doggy daycare, having the responsibility of pet ownership is not always a walk in the park. So why do we do it? The answer is, of course, is psychological in nature; pets provide mental health benefits that are hard to put a price on.

The history of pet ownership dates back to around 40,000 to 20,000 years ago when humans hunted in packs and lived nomadically in groups. Descended of course from the wolf, the dog was bred to work alongside their human owner, joining in on the hunt and alerting of intruders.

Cats too were bred to work; history suggests that around 4,000 years ago Egyptians were one of the first to breed smaller variations of jungle cats for the purposes of pest control. Some historians suggest that the trading giants of the ancient era, the Greeks, Romans, and Vikings, would never have had such control over the seas had they not had cats on board to deter vermin from destroying their wares.

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Though pets proved quite practical both on the hunt and in the house, history shows us that man’s relationship with his pets was not purely professional. Just as they do today, pets carried an important place in the emotional history of the people who raised them. Egyptians, for instance, regarded their cats as gods and mummified and entombed them alongside their owners.

The ancient Greeks and Romans, too, are remembered for their close connection with their pets, with many recording touching epitaphs at the passing of their furry friends. One Roman epitaph on a grave reads, “You who pass on this path, if you happen to see this monument, laugh not, I pray, though it is a dog’s grave. Tears fell for me, and the dust was heaped above me by a master’s hand.” And another: “I am in tears while carrying you to your last resting place as much as I rejoiced when bringing you home with my own hands 15 years ago.”

How can we explain the hold that pets have on our hearts, both then and now? Well, researchers have identified a few neurohormones critical to our human-animal bond; oxytocin and cortisol, and an evolved sense of attachment to our pets that is reminiscent of our attachment to babies.

Oxytocin, the "happy hormone" is neurochemical that is released when people experience satisfaction, and our brains use it as a signal for attachment which increases our ability to bond with others. Oxytocin is also a reason we feel so attached to our pets.

In a study by Nagasawa et al. (2015), dogs, their owners, and wolves had salivary oxytocin measured pre- and post-eye contact. Researchers found evidence of what they call an "oxytocin feedback loop," in which dogs and humans both experienced bumps in oxytocin in response to shared gaze between one another, an effect notably absent in wolves. The researchers hypothesized that over thousands of years, dog-human companionship has led both species to co-evolve a social responsiveness to one another, giving neurological support for the phrase "man’s best friend."

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Researchers have also found that animal contact has a significant effect on the body’s production of cortisol, another emotion-driven neurohormone. In contrast to oxytocin, cortisol can be thought of as our "unhappy" hormone, as its release signals to our body that we are distressed and thus preempts us to vigilance and the beginnings of a fight-or-flight type of response. While invaluable to our survival, when the body has an overactive flux of cortisol in the system, it means we are overly anxious and more easily provoked.

Enter pets. Research indicates that pets can provide a calming influence on their owners by decreasing cortisol levels after only a short interaction (3 minutes), after which both dog and owner cortisol levels significantly decrease (Handlin et al., 2011). Research also shows that even unfamiliar dogs can have this effect on humans; when compared to no contact or a familiar friend, only the presence of an unknown dog reduced participants’ cortisol levels during a stress test (Polheber & Matchock, 2014). Humans have a calming effect on animals too. After arriving in a shelter, dogs who had animal contact showed reduced cortisol in the following days than dogs who did not (Coppola, Grandin, & Enns, 2006).

Gray Atherton
Source: Gray Atherton

Finally, pets have a built-in mechanism that ensures their care and attention; their cute faces. The "Baby on Board" car stickers alerting us of precious cargo are just modern adaptations to what has evolutionarily speaking been humanity’s greatest goal; to ensure the survival of their youngest to make way for the generations to come.

Babies, of course, are hopeless at taking care of themselves, so enter caregivers and mother nature, who has hardwired us to attend to babies in several ingenious ways. From being primed to respond to a baby’s cry (Cecchini, Lai, & Langher, 2010), to almost instinctively knowing how to speak "mothers" to a non-verbal infant (Falk, 2004), and perhaps most represented in media (think Disney), the "baby-face" phenomena primes us to attend to a small face with larger than normal eyes (Lorenz, 1943), flooding us with oxytocin as we say "Aww."

Pet faces have a very similar effect on us too (and many more of us babytalk our pets than we would like to admit), with Borgi and Cirulli (2016) finding that this perceptual bias thought to prime caregivers to read the faces of their young charges also happens when we view pet faces (explaining our excessive kitten video viewing).

In closing, pets have been an important part of human history for millions of years, operating not just as practical watchdogs and mousers, but as members of our family and our source of comfort when the going gets rough. There are biological and cognitive mechanisms that in part explain this (oxytocin, cortisol, face schemas), but there are also individual differences that mediate how attached we get to pets and what situations change that attachment.

The ultimate challenge, of course, remains how we can practically use this information to transform the lives of those who need it most; the young, the old, the lonely, and the animals who are in need of their love. More on that soon.

For now, if you would like to take part in some research on pet ownership, click here.


Borgi, M., & Cirulli, F. (2016). Pet Face: Mechanisms Underlying Human-Animal Relationships. Frontiers in Psychology, 7, 298. doi:10.3389/fpsyg.2016.00298

Cecchini, M., Lai, C., & Langher, V. (2010). Dysphonic newborn cries allow prediction of their perceived meaning. Infant Behavior and Development, 33(3), 314-320. doi:

Coppola, C. L., Grandin, T., & Enns, R. M. (2006). Human interaction and cortisol: Can human contact reduce stress for shelter dogs? Physiology & Behavior, 87(3), 537-541. doi:

Falk, D. (2004). Prelinguistic evolution in early hominins: Whence motherese? Behavioral and Brain Sciences, 27(4), 491-503.

Handlin, L., Hydbring-Sandberg, E., Nilsson, A., Ejdebäck, M., Jansson, A., & Uvnäs-Moberg, K. (2011). Short-term interaction between dogs and their owners: effects on oxytocin, cortisol, insulin and heart rate—an exploratory study. Anthrozoös, 24(3), 301-315.

Lorenz, K. (1943). Die angeborenen formen möglicher erfahrung. Zeitschrift für Tierpsychologie, 5(2), 235-409.

Nagasawa, M., Mitsui, S., En, S., Ohtani, N., Ohta, M., Sakuma, Y., . . . Kikusui, T. (2015). Oxytocin-gaze positive loop and the coevolution of human-dog bonds. Science, 348(6232), 333-336. doi:10.1126/science.1261022

Polheber, J. P., & Matchock, R. L. (2014). The presence of a dog attenuates cortisol and heart rate in the Trier Social Stress Test compared to human friends. Journal of behavioral medicine, 37(5), 860-867.