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Elena Blanco-Suarez Ph.D.
Elena Blanco-Suarez Ph.D.

Does Animal-Assisted Therapy Work? - The Pet-Human Bond

What is the science behind animal-assisted therapy?

Every now and then I receive the newsletter from my alma mater to inform me about new programs, activities, and in general, make me feel like I’m still part of the family and under consideration. Since I’m a few thousands of miles away, I don’t pay much attention, as the most likely scenario is that I won’t be able to make it to whatever event they’re inviting me to across the pond.

However, a few months ago, something drew my attention. During final exams, they were offering students a “puppy room.” If students were feeling anxious or overwhelmed by finals, they could go to this room and relieve some of that stress petting and playing with cute puppies. I immediately felt jealous that such program was not implemented in my days as a grad student there. But I was happy to read that students’ mental health was being acknowledged and supported in this way.

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A room full of these will relieve your stress and anxiety.
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Pet therapy is not new. It has been around for over a century, and first popularized by Florence Nightingale, a nurse who noticed that patients with chronic illness felt better when they had the chance of interacting with animals. Now, pet therapy programs, also known as animal-assisted therapy, is offered not only at universities for stressed out students, but hospitals, nursing homes, and basically everywhere there are people.

Does Animal-Assisted Therapy Work?

There is extensive research on whether animal-assisted therapy works, and compelling data shows that pets have the ability to relieve stress, anxiety, and provide comfort to patients. However, it has been shown that the positive effects of playing and petting an animal are also measurable in people without underlying clinical conditions. In general, the interaction with a pet decreases distress and improves mood.

The effects of the pet therapy are measurable, as seen by an increase in the release of endorphins in the person interacting with the animal. Endorphins are brain chemicals that are released and make you feel good. Just like after a workout or eating a piece of yummy chocolate. Endorphins bind to and activate opioid receptors in the nervous system, acting like painkillers and producing euphoria.

Vicodin or Morphine are opioid pain medication that also bind and activate opioid receptors. These have a high potential for addiction and side effects. A dog visit certainly has fewer side effects than any dose of those drugs. Dogs make your nervous system release its own endorphins, so the body experience less undesired effects than medication.

Patients not only experienced an increase in endorphin release, but a decrease in secretion of stress hormones, like cortisol, norepinephrine, and epinephrine. This all contributes to the overall improvement that has been observed in patients exposed to animal-assisted therapy.

All Pets Do the Trick

You may think that this kind of therapy can only work on animal lovers, but several studies have demonstrated that people who report to feel neutral about pets also benefit from these interactions.

Dogs are the most popular pets in animal-assisted therapy programs, but the benefits derived from this kind of therapy are seen with other animals. Playing and petting a dog is nice, but therapies with crickets or animal farms showed that people improved their focus and mood by looking after these animals.

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The interaction with pets, from fluffy and soft dogs and rabbits, to turtles or even fish and crickets, will do the trick and make patients display the benefits of animal-assisted therapy.
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In a study published in 2003, 58 people without clinical diagnoses were told that they might be asked to hold a tarantula sitting elsewhere in the room. Even though they never actually had to hold the tarantula, the thought of it was enough to elevate their stress levels. Some participants were left in the room, mulling it over, while petting a soft, fluffy rabbit, whereas others were left in the same situation but petting a hard-shelled turtle. Either case, both groups experienced a reduction in stress and anxiety compared to those who didn’t have the chance to pet an animal while thinking of the tarantula.

Clearly, the beneficial effect is not related to the softness and fluffiness of the pet, instead it seems to be related to the bond between humans and animals in general. Other pets like fish and bearded dragons are also included in some variations of pet therapy, and studies show they’re equally beneficial for the patients.

Animals become the patient’s social partner, and for some people with psychiatric disorders it was also extremely positive to see themselves as the care givers, for a change.

This decreases anxiety, but also helps boosting their confidence to perform, also known as self-efficacy.

Pets Over Friends

But why use pets instead of interactions with other humans? After all, we know that social interactions have great benefits on the overall mental health.

However, humans are judgmental, and when you’re sick, stressed, or just trying to process life, pets won’t judge you, and they will be there for you unconditionally. Often times, the presence of a fellow human, even if it’s a friend, would contribute to our stress, even if that is not our friend’s intention. This was observed in a study with participants who were tasked to perform a simple activity in the presence of a friend, or a pet. The fear of failing in front of a friend in such a simple task was enough to raise the levels of stress hormones, whereas the people who were assigned the same activity in the company of a pet, showed no stress and in fact, they performed better.

We can say that pets provide a safe place for people, and during illness or emotional struggle, this can be very helpful in the process of recovery.

The Human-Animal Bond is Key

In the same study above-mentioned where participants were stressed over the thought of holding a tarantula, some were petting plush toy versions of rabbits or turtles, but this didn’t display the same effects on the human participants. The animals represent a distraction from other upsetting thoughts, whereas the plush toys don’t. Researchers showed with this experiment that the animal-human bond was important to get the positive effects, and not only the fact of petting something fluffy or soft, or animal-looking.

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The human-animal bond seems to be the reason for the positive effects derived from animal-assisted therapy.
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On the flip side, though, other studies with dementia patients have shown that robot dogs are effective at reducing stress and anxiety. The more the robot pets looked, sounded, and behaved like the real animal, the better was the response from patients.

Research still needs to pinpoint the underlying mechanisms that dictate all these benefits that come from interacting with animals, or why humans seem to be generally inclined to interact with animals with such positive outcomes. But ultimately, when it comes to animal-assisted therapy, most of the studies point at the human-animal bond as the key factor to achieve the positive effects.


Sprouse-Blum AS, Smith G, Sugai D, Parsa FD. Understanding Endorphins and Their Importance in Pain Management. Hawaii Medical Journal. 2010;69(3):70-71.

Marcus, D.A. The Science Behind Animal-Assisted Therapy. Curr Pain Headache Rep (2013) 17: 322.

Sicurella, T; Fitzsimmons, V. Robotic pet therapy in long-term care. Nursing. 46(6):55–57, 2016 doi:10.1097/01.NURSE.0000482265.32133.f6

Polheber, J.P. & Matchock, R.L. J The presence of a dog attenuates cortisol and heart rate in the Trier Social Stress Test compared to human friends. Behav Med (2014) 37: 860.

About the Author
Elena Blanco-Suarez Ph.D.

Elena Blanco-Suarez, Ph.D., holds a doctorate in biochemistry and has been working in the field of neuroscience since 2010. She collaborates in several science communication and education projects.

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