Humans have had dogs as companions for thousands of years. Over that time, dogs have evolved to become ever-better companions, as we humans selectively bred them for traits that we like, such as friendliness and loyalty.
Dog owners already know that owning a dog reduces stress. But it turns out that the health benefits of owning a dog go quite a bit further: two new studies published this month in the journal Circulation both found that owning a dog reduces your risk of dying.
The first study, by Carolyn Kramer and colleagues at the University of Toronto, reviewed ten other studies dating back more than 50 years, covering 3.8 million people. They compared dog owners to non-owners and found that dog owners had a 24% lower risk of dying, from any cause, over a 10-year period. The benefit was even greater for people who'd suffered a heart attack: those who had a dog at home after their heart attack had a 65% lower risk of dying.
These studies are consistent with many other scientific reports, stretching back decades. They're all consistent, and they all point in the same direction: dog ownership is good for your health. In fact, back in 2013 the American Heart Association issued an official statement on "Pet Ownership and Cardiovascular Risk" with this recommendation:
However, because the evidence was not very strong, the AHA also advised that people shouldn't get a pet "for the primary purpose of reducing CVD risk." In other words, don't get a dog if you don't want one. As every dog owner knows, owning a dog is much more trouble than simply taking a daily pill.
The new studies strengthen the previous evidence for the health benefits of dogs. In an accompanying editorial in Circulation, Dhruv Kazi from Harvard Medical School asks a critical question: is the association between dog ownership and reduced mortality just a correlation, or is it causal? He points out that studies have shown that dog ownership reduces blood pressure and other signs of stress, and that dog owners tend to get outside and walk more (with their dogs). Thus it's very plausible, medically speaking, that dog ownership is good for you. For these and other reasons, Kazi concludes that
"the association between dog ownership and improved survival is real, and is likely at least partially causal."