"A very interesting finding in our study was that dog ownership was especially prominent as a protective factor in persons living alone," said study author Tove Fall, "which is a group reported previously to be at higher risk of cardiovascular disease and death than those living in a multi-person household. Perhaps a dog may stand in as an important family member in the single households."
People who live alone have been shown previously to be at a higher risk of cardiovascular death.
The study looked at over 3.4 million Swedish individuals between the ages of 40 and 80.
Some of the benefits may be due to the increased exercise and social interaction a person gets from walking a dog.
"We know that dog owners in general have a higher level of physical activity, which could be one explanation to the observed results. Other explanations include an increased wellbeing and social contacts," Ms Fall said.
People who live with dog also get some extra exposure to microbes.
Previous studies have found reduced risk of certain health issues, like asthma and allergies, in kids who grow up with a dog.
Owners of hunting breeds, including terriers, retrievers, and scent hounds, were most protected from cardiovascular disease and death.