Another possible explanation, he adds, could be a dog's effect on its owner's microbiome. "It's not so easy to combine dogs with an active work life and they aren't always allowed in places, so the study could help us to understand that dogs are really important for their owners, and for example be more understanding if someone's dog passes away".
The heart-health benefits of being a dog parent were especially pronounced among people living alone (in this case, meaning without other humans), which, according to the study's authors, is a group reported previously to be at higher risk of cardiovascular disease and death than those living with other people.
The team from Uppsala University in Sweden analysed data from 3.4 million Swedes aged 40 to 80 by combing through a national database of hospital visit records and dog ownership registrations.
Although these large-scale studies based on massive data sets like the national registries in Sweden are an interesting and helpful way of finding associations, it doesn't provide specific answers about how having a dog improves heart health. Dog ownership has also been linked to elevated parasympathetic and diminished sympathetic nervous system activity, lower reactivity to stress and faster recovery of blood pressure after a stressful activity.
The scientists followed 3.4 million people over the course of 12 years and found that adults who live alone and owned a dog were 33 percent less likely to die during the study than adults who lived alone without dogs.More news: Norway's state fund 'needs to ditch oil and gas investments'
Hunting breeds such as Golden Retrievers, Irish Setters and Beagles achieved the best results.
And how do dogs go about keeping one heart-healthy?
"However, as many dog owners may agree, the main reason for owning a dog is the sheer joy".
"We can not infer a causal relationship, however, dog ownership is associated with increased physical activity, improved psycho-social wellbeing and socialisation, all of which are associated with reduced CVD mortality- so it is plausible the effect is mediated though these mechanisms".
While some previous studies have shown similar positive effects for pet ownership generally, others have shown the opposite effect. Because these dogs typically need more exercise than other breeds, their owners may be more likely to meet physical activity guidelines, they say.