The nation’s largest cardiovascular health organization has a new message for Americans: Owning a dog may protect you from heart disease.
The unusual message was contained in a scientific statement published on Thursday by the American Heart Association, which convened a panel of experts to review years of data on the cardiovascular benefits of owning a pet. The group concluded that owning a dog, in particular, was “probably associated” with a reduced risk of heart disease.
People who own dogs certainly have more reason to get outside and take walks, and studies show that most owners form such close bonds with their pets that being in their presence blunts the owners’ reactions to stress and lowers their heart rate, said Dr. Glenn N. Levine, the head of the committee that wrote the statement.
But most of the evidence is observational, which makes it impossible to rule out the prospect that people who are healthier and more active in the first place are simply more likely to bring a dog or cat into their home.
“We didn’t want to make this too strong of a statement,” said Dr. Levine, a professor at the Baylor College of Medicine. “But there are plausible psychological, sociological and physiological reasons to believe that pet ownership might actually have a causal role in decreasing cardiovascular risk.”
Nationwide, Americans keep roughly 70 million dogs and 74 million cats as pets.
The heart association publishes about three scientific statements each month, typically on more technical matters, but the group was prompted to take a stance on the pet issue by the growing number of news reports and medical studies linking pet ownership to better health.
Dr. Levine noted that the more traditional methods of risk reduction for heart disease had proven effective, and that now was a good time to investigate alternative approaches. “We felt this was something that had reached the point where it would be reasonable to formally investigate,” he said.
Dr. Richard Krasuski, a cardiologist at the Cleveland Clinic, viewed the new statement as an indictment of societal attitudes toward exercise.
“Very few people are meeting their exercise goals,” he said. “In an ideal society, where people are actually listening to physician recommendations, you wouldn’t need pets to drag people outside.”
The new report reviewed dozens of studies, and over all it seemed clear that pet owners, especially those with dogs, the focus of most of the studies, were in better health than people without pets.
“Several studies showed that dogs decreased the body’s reaction to stress, with a decrease in heart rate, blood pressure and adrenaline-like hormone release when a pet is present as opposed to when a pet is not present,” Dr. Levine said.
Pet owners also tended to report greater amounts of physical activity, and modestly lower cholesterol and triglyceride levels. Some research showed that people who had pets of any kind were also more likely to survive heart attacks.
In one of the only randomized controlled studies included in the report, 48 stressed stockbrokers with hypertension were put on medication that lowered their blood pressure, and then researchers divided them into groups. Those in one group were told to adopt a dog or cat. Six months later, the researchers found that when the stockbrokers who had adopted pets were around their new companions, they were markedly calmer in the face of stressful events than the stockbrokers without pets.
But nearly all of the other studies included in the report were correlational, meaning they could not prove cause and effect. And the research also strongly suggested that among dog owners, there was a sharp contrast between those who walked their dogs themselves and those who did not.
Data from the Centers for Disease Control and Prevention shows that pet owners are just as likely to be overweight as people without pets. One large study involving thousands of people found that 17 percent of those who walked their dogs were obese, compared with 28 percent of dog owners who did not walk their dogs and 22 percent of those without pets.
Dr. Levine said that he and his colleagues were not recommending that people adopt pets for any reason other than to give them a good home.
“If someone adopts a pet, but still sits on the couch and smokes and eats whatever they want and doesn’t control their blood pressure,” he said, “that’s not a prudent strategy to decrease their cardiovascular risk.”
By ANAHAD O'CONNOR The New York Times
