Are Pets Really Good For Us?

We all know that pets are good for us, right?  They keep us physically healthier by reducing blood pressure and heart disease and prolonging our lives after heart attacks.  They improve our mental health, reduce depression and make us happier. Don’t they?  Maybe not.  A recent review paper by Dr. Harold Herzog of Western Carolina University, challenges this belief that has become one of the most cherished Sacred Cows of the Human-Animal Bond.

Herzog found that while the studies finding a positive benefit of pet ownership (known as the “Pet Effect”) go back over 30 years and have been widely publicized, studies finding no effect or even a negative effect have been all but ignored.  More troubling is the fact that the negative results aren’t just a couple of poorly done studies that can be easily dismissed, but instead constitute a significant number of studies, that are at least the same quality as those demonstrating positive benefits of pet ownership.

For example, one of the earliest studies to find a beneficial effect of pets was by Friedman et al in 1980.  They found that heart attack survivors who owned pets were significantly more likely to survive at least a year compared to those without pets. However recent research that tried to replicate the Friedman study with a much larger sample found that pet owners were less likely to survive their first year after a heart attack than were non-pet owners.    

Well, maybe pets don’t make us healthier, but they make us less lonely, don’t they?  At least one study has supported this belief but another found that pet owners were just as lonely as non-pet owners. So what are we to make of these contradictory findings?

Herzog points out several possible reasons for the discrepancies. The quality of the research in the human-animal bond area has not been consistently high.  Many studies are observational, simply comparing pre-existing groups (pet owners and non-pet owners) with regard to some measure of health or well-being.  Some studies have very small sample sizes, making chance effects more likely to arise.

And then there is the issue of bias by the researchers.  Many of those doing the research strongly believe in the positive effects of pets on people and their beliefs can bias their results, either consciously or unconsciously.

What should be done in light of these conflicting results?  There probably is a positive effect of pets either in certain situations, with certain people or both.  The only way to discover the precise nature of that effect is more and better research.  As Herzog states in his paper,

“Most pet owners believe that their companion animals are good for them. Personal beliefs and heart-warming anecdotes, however, do not constitute scientific evidence. Claims about the medical and psychological benefits of living with animals need to be subjected to the same standards of evidence as a new drug, a medical device, or a form of psychotherapy.”

Our failing has been to readily accept the “pet effect” as fact, based on inadequate evidence. There is a larger lesson here. This sort of blind acceptance of a phenomenon can quickly happen in any research area when we want to believe in the phenomenon, when it “makes sense” to us or when there are groups that can benefit financially or politically from the existence of the phenomenon.  We should be more cautious in accepting these Good News findings in the future.

Herzog, H. (2011). The impact of pets on human health and psychological well-being: Fact, fiction or hypothesis. Current Directions in Psychological Science, 20 (4), 236-239.

1 Comment

  • Jenny Haskins

    Reply Reply September 26, 2011

    It’s a worry isn’t it! This bias in publication.

    Personal experience has shown me the down-side of pet ownership as well as the up-side.
    However I cannot imagine living without my dogs.

    Surveys of course always are studying ‘unequal’ groups — I presume the pet owners were pet owners by choice, and the non-pet owners were petless by choice?

    Maybe the research should look at matched groups, one with pets fopist upon them, and one withput pets.

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