I have to admit that the reason why I decided to write this post is completely and entirely selfish. This week, I turned 6 months as a cat owner of the most wonderful, loving and vocal little kitty I've ever seen (all other cat owners will have to excuse this statement and please don't give up on reading)! Spooky is an adopted kitty - she came from a place (I would never call that a home) where she and other cats were mistreated, abused and anything but loved. So when we got her, all she wanted was love and pettings. In return, I could swear, she gave us so much more - joy, purpose, laughs and comfort, and I'm sure we're not the only ones.
Anyway, the scientist in me was wondering all the while if her effect on me was just me fooling myself, or was it may be a truly physiological and psychophysiological response to her presence in my life. In the end, I finally set out on a quest to find out by consulting the scientific literature. I was unconvinced at first - as a molecular biologist it's sometimes hard to understand and trust behavioral studies - there can be so many confounding factors that might be the reason for the results obtained. But then I weighed the scientific methods behind a molecular experiment and some of the method descriptions I could find in behavior and psychophysiological research and I had to correct myself - a well conducted study in those "soft" sciences was as conclusive and as valuable as a well conducted one in the "hardcore" biology. So here goes:
How can we know if your pet is making you happier?
1 Some of the studies which had addressed this question (in the past 20 years there are many of them) rely on self reporting. These are usually studies, which are hard to control completely, as often the subject reports specific information back to the scientist after specific time as a member of a group subjected to treatment or as a control. Nonetheless, there are ways to conduct such studies in a manner which allows to draw conclusions with sufficient confidence in the data reported by the subjects. Such as: social attention, social behavior, interpersonal interactions, and mood.
2Other studies, are conducted in the controlled environment of a dedicated area or even a lab, where the random influence of unexpected factors is kept to a minimum. The drawback of these being that out of the natural environment of the tested subjects, effects might very well vary, but again - with sufficient control on the experimental setup and big enough number of tested subjects, conclusions can be of great value. What gives confidence to this and the previous study type is design which includes a control group next to the before-after treatment groups.
3 My absolute favorite type of studies is the one where the presence and/or magnitude of a psychological effect is measured empirically. I'm still biased by my own scientific knowledge, and I am honest about it to myself - I will prefer a study which measured something tangible to a study that resorted to only (somewhat) subjective reporting of an effect. Hence, some of the studies reviewed in this post are ones that measured levels of hormones, neurotransmitters, blood pressure, and heart rate to try and pinpoint the physiological event accompanying a psychological response.
The indirect ways your pet might be making you happier:
You are more likable if you own a pet
Turns out, people perceive others in a more positive light when they are seen with a pet. Being liked is a general human behavior determinant and an aim for our (sub)conscious, whether we recognize it in our own attitude and actions or not. Being liked generally starts a feedback loop in individuals where when the cause for the "liking" is identified this behavior is further retained. You are overall happier when people like you, especially people you yourself like.
People would trust you more if you own a pet
Disclaimer: I never understood why bikers are perceived as generally threatening personalities - this representation is just for giggles.
Another study showed that people report themselves more trusting (the image of) a person next to a dog, compared to the person alone. Being trusted by others is often positively supporting the self-worth estimation of people, hence again - if people trust you, you probably feel better about yourself and will be generally happier. Unfortunately, there was a difference when the dog was from a breed generally perceived as family-friendly as compared to a breed considered aggressive. I say unfortunately, because a whole different set of studies shows that while some breeds of dogs were indeed bred for aggression, the behavior of the individual dog depends predominantly on the way it has been raised and the expectations to its training - if you are aggressive to a dog, chances are it will be aggressive in return, irrelevant of its breed.
In many establishments the inclusion of therapy animals is a standard practice. Resident or visiting therapy animals are used in nursing homes for the elderly, in psychiatric wards, in psychological assistance centers, in rehab clinics, in special care wards and in children behavior research centers. In all cases where a scientific study has been conducted, the presence of a therapy animal has significantly increased the overall well being of the patients and their satisfaction with the care. These animals have facilitated the communication with difficult to approach patients and allowed for direct communication with autistic kids much more than a stuffed animal or any other "comfort" object used as a comparison.
But how does exactly your pet make you happier?
Are you "hormonal"?
Indicators like serum cortisol, epinephrine, and norepinephrine as well as salivary cortisol can provide hints on the general condition of the individual. These are all hormones related to the stress levels. A significant reduction of serum and salivary cortisol was observed when a medical practitioner had a rest for 20 minutes in the presence of a puppy, as compared to resting alone.
A furry chill-pill
When it comes to heart rate, blood pressure and sweating in response to a stressor, the presence of your own or even a random friendly animal helps reduce the negative effect of the stress factor. Some studies show overall less-negative effect of it when a pet is present, others - better restoration to the baseline compared to people subjected to the stressor on their own. In some studies, the pet had a better effect than the presence of a friend or even a spouse in the same set up!
A happiness injection
The authors of this very comprehensive systematic review covering all the studies mentioned above, hypothesized that the positive effect of friendly animals is due to one thing - a surge of oxytocin in the brain and circulation of the studied subjects. According to their conclusion, the physiological and psychological effects observed with the introduction of a pet in the study set-up is very similar to supplementation with oxytocin. Some studies even went into the details of whether the sole act of petting a dog is sufficient to calm post-stressor subjects, or the presence of the pet itself is necessary, and it turns out the petting of an object alone is just not going to cut it - you need the real deal!
"The peptide hormone oxytocin is produced in the hypothalamus and released into the circulatory system and the brain in response to sensory stimulation via a network of oxytocin-containing nerves e.g., during breastfeeding, labor, sex, but also touch, warmth, and stroking, usually in the context of trusting relationships."
Keep calm and love your pet
So there you have it - there is a whole lot of scientifically sound evidence as to why and how your pet is making you happy. I doubt anyone really needed justification for the love towards their animal companion, but if you were curious - these are the answers researchers have in store so far. Since in many animals the oxytocin has a similar effect as in the human brain, this will be an interesting start to many other studies, including ones focusing on animal behaviour. Now go to your pet and feed, scratch, walk, play with or just continue to adore it, being confident that you are doing the scientifically correct thing.
Some considerations regarding these studies:
Who were the subjects?
Obviously, the observed and reported effects in all these studies will vary if your test subject was someone with generally or strongly negative attitude towards animals. In fact, it is possible that the effects will be completely the opposite, although I'm still to find such study (but it might be actually unethical to conduct a study where you force people who fear animals be in the same room with them at the same time you introduce additional stressor...). All of the studies in the literature I've found have at least a neutral attitude towards animals or are actually animal lovers. This does not render the studies unless - not at all, but it needs to be remembered when these studies are reviewed or implemented in different contexts.
What animals were used?
Mostly, in human-animal interaction studies, as a therapeutic/positive-effect animal was used a well trained, friendly and generally well perceived animal. Most often these were dogs, sometimes cats and in few particular studies - fish and birds. As it turns out, fish do have positive effect on the subjects, but the limited contact with them makes a difference for the overall magnitude of this effect. I suspect that if exotic and more "frightening" animals are used, the results will be quite different.