Are pets good for your health? Maybe. But Then Again, Maybe Not.

Pet owners are a unique breed. Even those that hadn’t wanted a pet often find themselves enthralled once they join the ranks of proud possessors of a furry (or not so furry; we don’t discriminate) companion. Witness Adam Gopnik’s recent tale of dog-ownership in the New Yorker. And that’s all well and good; pets can make people happy.

But then, enter the actual health claims: People with pets live longer. They have lower blood pressure. They sleep better. They are more physically fit. They have less stress. Higher self-esteem. Greater life satisfaction. It’s the so-called pet effect. Doesn’t that sound like we should all run out and get ourselves a pet?

Just as much evidence shows that pets aren’t all that good for you after all

Not so fast. Harold Herzog’s recent analysis of studies from the past thirty years comes to a surprising conclusion: the pet effect is nothing more than an unsubstantiated hypothesis. For every study that shows some value of pet ownership, there are several that show absolutely no benefit at all – and in some cases, even negative effects. Only, those studies don’t get any media coverage. It’s tough to applaud negative or null findings.

Consider this. A 2001 study showed that subjects who had been put in a pet group showed lower increases in blood pressure under stress six months later. But, a 1997 study found that doing something stressful in the presence of a dog had no effect on blood pressure, while a 2007 study of 1,179 older adults found no differences in blood pressure between pet and non-pet owners.

In 1980, a study of 92 heart attack victims showed that 28% of those with a pet survived for at least a year after, while only 6% of non-pet owners did. But, a 2010 study of 425 heart attack victims found that pet owners were actually more, not less, likely than non-pet owners to die or suffer remissions within a year of heart attack, at a rate of 22%, as compared to 14% of non-owners.

Even happiness self-reports have come into question: in 2010, 3,000 Americans were surveyed about their happiness; non-pet owners were just as likely as pet owners to report being very happy (note: this says nothing about pets not making you happy; only that owning a pet doesn’t necessarily make you any happier than not owning one). And a 2011 study of dog owners found that those who were more attached to their pet were actually more depressed than those who were not. Meanwhile, over in England, people who had acquired pets were just as lonely six months later as they had been before the purchase; in Sweden, in a sample of 40,000 individuals, pet-owners suffered from greater psychological problems, such as anxiety, chronic tiredness, depression, and insomnia; in Finland, out of 21,000 adults, pet owners were at a higher risk of hypertension, ulcers, migraines, high cholesterol, depression, and panic attacks; and in Australia, out of 2,551 older adults, those who owned dogs were in poorer physical health and more likely to be depressed.

So what does that mean – and why does it matter?

None of this means that pets are bad for you. That’s not the point. The studies are pure correlation. Nothing whatsoever implies causation. But: it does mean that you can’t draw the opposite conclusion either. You can’t believe the studies that are also purely correlational that show the benefits of pet ownership, even if they make more sense to you. Either side has an equal shot at being right; and for now, the evidence is ambivalent at best.

Instead, be skeptical. It’s only natural to seek confirmation of what we already believe. It’s called the confirmation bias, and it plays into almost any decision we make. It’s something that we always need to take into consideration – even if it means that even the most “common sense” and “logical” thing in the world should be questioned. It’s not common sense and logical to everyone.

Let me add a full disclosure here. I’ve owned a pet twice in my life: a goldfish that I named Blow-eyes—because she (or at least in my mind, it was a she) had puffy eyes—and flushed down the toilet when one morning, I found her floating belly-up in the tank; and a guinea pig that I named Guinea—because, well, I was a very creative child—and returned to the pet store a mere six months after I got him, when he bit my finger (that, and I never much cared for smells or litter or any of the trimmings that came along with my little pet). So I, too, am biased. I very much doubt I’d be writing this article if I owned a pet – but then again, it shouldn’t matter, should it, in the service of impartial science?

Pets might very well be good for you. But then again, they are just as likely not to be. That doesn’t mean your pet is not beneficial. That doesn’t mean he doesn’t make you happy. But does he have to add years to your life, take away pounds from your waistline, relieve stress, and improve your sleep as well? Or can he just make you happy because you like having a pet? There’s nothing at all wrong with the second alternative. 

[photo credit: Creative Commons, dok1 flickr photostream]