Benefits of puppy love

Two additions to this collection of evidence come from two articles published in the October 2019 issue of Circulation: Cardiovascular Quality and Outcomes.

The first article, an analysis of multiple studies, found that compared with people who didn’t have dogs, dog owners were on average 24% less likely to die over a 10-year period, and 31% less likely to die from a heart attack, stroke or other cardiovascular condition. The second was a study looking at how dog ownership affected survival once people left the hospital after a heart attack or stroke. Using data from the Swedish National Patient Register, the researchers looked at how well people who owned dogs fared when compared with people who weren’t dog owners. Study subjects included people ages 40 to 85 who had a heart attack or ischemic stroke (the type caused by a blocked blood vessel in the brain) between 2001 and 2012.

Demographic data show that dog owners are more likely to be married, which has been linked to better health. They’re more likely to have the physical space for a dog, which means they might have a higher income level. But even after adjusting for those and other confounding factors, evidence of a benefit appears to remain in the data, says Kazi. “After reviewing the literature, it’s my conclusion that there is very likely some effect from having a dog,” he says.

He cites several possible reasons for this apparent benefit:

Studies show that people who have a dog exercise more and spend more time outside, when compared with those who don’t, says Kazi. This is true simply because people have to walk their dogs and care for them. Both the exercise and the outdoor time can bring benefits, such as lowering blood pressure and cholesterol and improving heart rate.

Stress is another known risk factor for heart disease. A 2001 study found that pet ownership in conjunction with treatment with an ACE inhibitor did more to reduce stress-related blood pressure spikes than ACE inhibitor treatment alone. A 2007 study found that in people hospitalized for advanced heart failure, blood pressure and levels of certain stress hormones dropped after a 12-minute visit from a therapy dog.

“Another big part of the benefit of dog ownership is probably its effect on mental health,” says Kazi. People who own dogs forge a connection with their pets, which could make them feel happier. This effect may be greater for people who live alone, who may be at higher risk for anxiety and depression. “It’s likely that there is also a strong mental health benefit that may translate into better cardiovascular health and survival,” says Kazi.

Dogs may also have an effect on the human body’s intestinal bacterial population known as the microbiome, because they introduce germs to the home, says Kazi. These microbiome changes may help heart health, an effect similar to that seen when you eat healthy probiotics found in fermented foods.

Can cat lovers get the same benefits? “The available evidence is almost entirely about dogs,” Kazi says. There may be some mental health benefits from cat ownership. But you’re not getting the same physical benefit of exercising. Until there are more studies, it’s hard to extrapolate these findings to other pets, he says.