A new study of more than 3.4 million people finds that owning a dog is linked to a longer life. The research, published in Scientific Reports, is the latest in a growing body of research suggesting that canine companions may be good for human health—especially for people who live alone.
To study the link between dogs and longevity, researchers at Sweden’s Uppsala University reviewed national registry records of Swedish men and women, ages 40 to 80. They focused on 3.4 million people who had no history of cardiovascular disease in 2001, and followed their health records – as well as whether they registered as a dog owner – for about 12 years. Dog ownership registries are mandatory in Sweden, and every visit to a hospital is recorded in a national database.
Researchers found that dog owners had a lower risk of death due to cardiovascular disease than people who did not report owning a dog, as well as a lower risk of death from other causes. That was true even after adjusting for factors such as smoking, body mass index and socioeconomic status.
The protective effect was especially prominent for people living alone, who have been found to have a higher risk for early death than those who live with other people. People who lived alone with a dog had a 33% reduced risk of death, and an 11% reduced risk of cardiovascular disease, than people who lived alone without a dog.
The study – with a sample size hundreds of times larger than any other studies on this topic – was not designed to show a cause-and-effect relationship between dog ownership and reduced risk of death or cardiovascular disease, or to determine why these factors may be related. It’s possible that people who choose to own dogs may simply be more active and in better health to begin with, say the authors.
But it’s also possible – and very likely, says senior author Tove Fall, a veterinarian and associate professor of epidemiology – that taking care of a dog prompts people to stay active and live a healthier lifestyle. “I have met numerous owners that are convinced that their pet has been instrumental for them, often in terms of social support,” says Fall. “As a dog owner, I also notice that the people I meet during walks are often other dog owners, especially in bad weather.”
Another possible explanation, he adds, could be a dog’s effect on its owner’s microbiome. Other studies have suggested that growing up with a dog in the house can decrease allergies and asthma in children, and Fall says that pets may provide immune-boosting benefits for adults as well. Studies have also suggested that dog owners have lower reactivity to stress and faster recovery of blood pressure following stressful events.
The study authors were surprised to find that people who owned dogs that were originally bred for hunting – like terriers, retrievers and scent hounds – were the most protected from heart disease and death. Because these dogs typically need more exercise than other breeds, their owners may be more likely to meet physical activity guidelines, they say.
Fall says the study’s results can be generalized to the entire Swedish population, and likely to other countries with similar living standards and culture regarding dog ownership.
Scientists can’t say that getting a dog will definitely help a person live longer, but Fall believes it’s not a bad idea. “I think that a pet brings a lot of joy and companionship into a house, so if a person has the capacity to take care of it, they certainly should,” she says. “There are numerous studies showing that dog owners get more physical activity, which could help to prolong a healthy life.”