While writing Some We Love, Some We Hate, Some We Eat: Why It's So Hard To Think Straight About Animals I learned some things that really surprised me. For example, the evidence that pets enhance human health and pychological well-being (the so-called "pet effect") is weaker than I thought.
The Hounds Are At My Heels!
I can hear the howls already. If you are reading this post, you are probably a pet lover. And you are probably convinced that your pets make you a happier and healthier person. That's my experience with pets too. Like most people, I thought "the pet effect" was a firmly established scientific fact. I had read books like Marty Becker's The Healing Power of Pets, and a host of newspaper and magazine articles on the psychological benefits of pet ownership. Further, Marc Bekoff, Stanley Coren and Allen McConnell ,all excellent scientists, have promoted the health benefits of pets in their Psychology Today blogs. I had also encountered many scientific journal articles that began with a statement like, "The health and psychological benefits of pets on human physical and psychological health are now well-established," and I had heard a slew of conference presentations on "the pet effect."
But when I started doing the research for the pet chapter in my book, I sorted the scientific journal articles I had amassed into three stacks based on their results -- the "good pile," the "bad pile" and the "ugly pile." I was shocked by what I found. (See here for the published report.)
First, the Good News...
The good news is that a lot of studies (the "good pile") found that health and psychological benefits accrue from living with animals. Indeed, the field of anthrozoology -- the study of human-animal relationships -- was jump started by Erika Friedmann's groundbreaking study showing that the one-year death rate of heart attack victims who owned pets was one fourth that of people who did not live with companion animals. In the three decades since Erika's study, other benefits of pets on health and psychological well-being have been documented by researchers. These include lower blood pressure and psychological stress, decreased doctor visits and missed days of work, better sleep, increased self-esteem, decreased loneliness and depression, healthier attachment styles, and higher levels of physical activity.
Now, the Bad News...
But as I began to collect more and more articles on pets and health, I was surprised at the number of studies which found there were no differences in the health or happiness of pet owners and non-pet owners. Further, this "bad pile" of articles kept getting bigger and bigger. Among these were studies reporting that pet ownership was NOT associated with decreased psychological stress, blood pressure, heart rate, or depression - or increased levels of happiness, life satisfaction, exercise. And I could find no evidence that pet owners as a group lived longer.
Finally, the Really Bad News...
Then there was the "ugly pile" -- the studies that found that pet owners were actually worse off than non-pet owners. (Note that this pile did not include the studies of pet-induced injuries, for example, the 85,000 people each year who are taken to emergency rooms because of falls caused by tripping over their pets or the 800,000 individuals - mostly children - who receive medical attention for dog bites, or the fascinating array of diseases people can contract from pets, such as MRSA, salmonella, hookworm, toxoplasmosis and cat-scratch fever.)
The ugly pile consisted mostly of epidemiological studies in which pet owners were found to be at greater risk than non-pet owners for problems such as depression, anxiety, panic attacks, chronic tiredness, insomnia, obesity, hypertension, gastric ulcers, high cholesterol, and migraine headaches. One study, for example, found that pet owners had elevated diastolic blood pressure, higher BMI's and were more likely smoke cigarettes. Then there is the 2010 study of how heart attack victims fared a year after their initial coronary. After taking demographic and basic health differences into account, the researchers discovered that the pet owners in the group were twice as likely as non-pet owners to have either died of a heart attack or to have been readmitted to the hospital for cardiac problems. Ouch!
The Bottom Line
But, you ask, if the research on the "pet effect" is such a muddle of inconsistency, why do so many people believe it is an established scientific fact? One reason is that we want to believe that our pets are good for us. Another is that the media loves "feel good" animal stories, yet usually ignores studies that do not support the pet effect hypothesis. In addition, the $50 billion dollar a year pet products industry is pushing the idea that a sweet little Yorkie can lower your blood pressure, make you lose weight, and drive away the blues.
The bottom line, however, is that despite 30 years of research, "the pet effect" is presently not an established fact but an as yet unsubstantiated hypothesis. I will discuss some reasons why the studies on of pets on human health and happiness are so inconsistent in my next PT blog post. Stay tuned.
But right now, my cat Tilly is meowing. She wants me to stop writing this post and play a round of "chase the laser pointer red dot." Gotta go....
Hal Herzog is a professor of psychology at Western Carolina University. His book Some We Love, Some We Hate, Some We Eat: Why It's So Hard to Think Straight about Animals is now available in paperback.