Dog ownership correlates with lower rates of mortality and some fatal diseases, particularly cardiovascular disease, a study published this past week concluded.The study in the journal Scientific Reports found that canine ownership was associated with "lower risk of CVD in single-person households and lower mortality in the general population."The risk of death was found to be about 33 percent lower for single dog owners than nonowners, and the risk of heart attack was 11 percent lower, according to the study.Based in Sweden, almost 3.5 million people ages 40 to 80 were observed from 2001 to 2012 for the study. The authors called their findings the biggest investigation of the link from dog ownership to human health "by far."Older studies have suggested that the risk of heart disease is higher among people who live alone. Dogs could help with that. The study says: "One mechanism by which dog ownership could reduce CVD risk and mortality is by alleviating psychosocial stress factors, such as social isolation, depression and loneliness — all reportedly lower in dog owners."Hunting breeds appear to correlate with the lowest risk of cardiovascular disease, the study says."Perhaps a dog may stand in as an important family member in the single households," said Mwenya Mubanga, lead junior author of the study, in a news release accompanying the study.The exact mechanism by which dogs help people’s health is not clear, but several explanations are possible."We know that dog owners in general have a higher level of physical activity, which could be one explanation to the observed results," the study’s senior author, Tove Fall, said in the news release. "Other explanations include an increased well-being and social contacts or effects of the dog on the bacterial microbiome in the owner."