Are pets good for your health? You may be surprised…

I didn’t grow up with dogs, so until recently I didn’t have much experience with them. But then our “grand-dog,” Max, entered the family (owned by daughter and son-in-law Hannah and Mike). And I can say, completely scientifically and objectively, that Max is in fact the cutest dog in the entire world. Here’s the picture to prove it:

I have found another interesting thing about having Max around. When we’re dog-sitting, he gets us out of the house for regular walks, and his cheerful and curious personality tends to brighten our moods. So it seems logical that a pet like Max would make us healthier.

And of course, there’s one thing we Americans want: If we like something, we want to know it’s good for us. We just can’t be satisfied if something is fun (taking walks) or tastes good (blueberries, chocolate) – we also want someone to say it’s healthy.

Often, you will see claims that pet ownership is good for our health. Sometimes, this claim appears on sites that are selling pet products, other times it will appear on medical and health websites. But one thing everyone who reads Evidence-Based Living knows: What we look for are scientific, systematic reviews of the literature. Individual studies may show one thing, but what happens when you put together all the sound available research? Sometimes you get a surprise.

And so it is, apparently, with the health benefits of pet ownership. A fascinating review has been published by Anna Chur-Hansen, Cindy Stern, and Helen Winefield that examines the research linking companion animals to health. Looking at the existing literature, they conclude: “Results have been inconclusive, with positive, neutral, and negative effects variously reported in the literature.”

It’s not that there’s evidence that pets aren’t healthy for you; rather, there is no conclusive evidence either way.

Here’s the biggest problem: Very little research exists that has used randomized, controlled designs, in which some people are provided with companion animals and others aren’t. Rather, studies look at current pet owners versus non-pet owners, which introduces major bias: People who choose to have companion animals are likely to be different from people who aren’t, so the comparison doesn’t work. For example, in studies reported in a New York Times article, it may seem that people who get a dog walk more. However, the research found that people bought dogs because they wanted to walk more (rather than the increased walking caused by buying a dog). 

Another problem in previous research is that pet ownership isn’t compared to other interventions that might be equally beneficial to individuals. One study of older people, for example, found that promoting exercise directly is more likely to lead to improved health than pet ownership.

Because of the lack of well-controlled research studies, the health claims are largely based on descriptive research or quantitative data based on weak designs (indeed, the systematic review found too few high-quality studies of the effect of companion animals on health to allow any conclusions to be drawn). It’s not that studies are finding negative effects of pet ownership, rather research increasingly shows that there is no measurable effect on things like living longer or psychological well-being.

There are two conclusions to be drawn here. First, the lesson appears again that we’ve seen so many times on this blog: We have to look beyond individual studies to scientific reviews of the literature, and we must look at the quality of study design to understand what promotes health.

Second, I love Max every bit as much as I did before I read this stuff.