But it may not be dog ownership itself that helps the owner live longer—it's as likely to be because owners have to walk the dog, and so are more active. Other possibilities are that the dog increases the owner's social contact, or that dirt the dog brings into the home changes the owner's gut microbiome, making him or her less susceptible to a heart attack.
Whatever the reason, the health benefits of dog ownership are impressive. The risk of premature death drops by around 33 per cent, and chances of a heart attack are reduced by 11 per cent, say researchers from Uppsala University in Sweden.
They studied the health of around 3.4 million Swedes, 13 per cent of whom owned dogs, for up to 12 years. To tease out the benefits of dog ownership, the researchers focused on single people living alone—as that's a recognised risk of heart disease—and compared the health of the dog-owners against that of those who didn't have a dog.
The one flaw in the study, say the researchers, is that active and more social people could be buying a dog, and so were less likely to have heart disease in the first place.