Dogs really are man's best friend, as owning one can slash the risk of premature death by a third, according to major new research.
The landmark study of more than 3.4 million older people found Britain's favorite pet reduces the likelihood of heart disease and combats loneliness.
Those living alone were 33% less likely to die over the next 12 years if they owned a dog.
The biggest impact was seen on cardiovascular disease, the world's biggest killer, reducing mortality rates by a staggering 36%.
Scientists said the companionship was key, along with the physical activity in taking it for a walk. Hunting breeds such as Golden Retrievers, Irish Setters, and Beagles achieved the best results.
The findings come in the wake of a warning from Britain's top GP that loneliness is killing millions of Britons and is as dangerous as high blood pressure diabetes and depression.
According to the Campaign to End Loneliness, an estimated 1.1 million over 65s in the UK are chronically lonely and more likely to develop heart disease and dementia.
The nationwide analysis in Sweden found even those living in families or with partners were 15 and 11 percent less likely to die from cardiovascular disease or any cause, respectively, over the period.
But the effect on single, divorced and widowed individuals were three times more dramatic.
Senior author Professor Tove Fall
, an epidemiologist at the Science for Life Laboratory, Uppsala University, Sweden, said single owners may walk their dog more and have increased interaction compared to members of a family.
He said research has long associated Dog Ownership
with good health but this was 100 times bigger than any previous study of its kind.
As it was an observational study it does not prove dogs prevent cardiovascular disease or how it may happen.
But Prof Fall said: "We know dog owners, in general, have a higher level of physical activity, which could be one explanation to the observed results.
"Owning a dog is associated with reduced mortality and risk of having heart disease," said Dr Mike Knapton, associate medical director at the British Heart Foundation.
"Previous studies have shown this association but have not been as conclusive - largely due to the population size studied here.
"This association between dog ownership and risk of death from cardiovascular disease (CVD), was identified from Swedish registers and the national dog ownership register.
"We cannot infer a causal relationship, however, dog ownership is associated with an increased physical activity, improved psycho-social well-being and socialization, all of which are associated with reduced CVD mortality- so it is plausible the effect is mediated through these mechanisms.
"Alternatively it could be reverse causality - people who are fitter and more active are more likely to own a dog."
The study by Professor Tove Fall, an epidemiologist at the Science for Life Laboratory, Uppsala University, and colleagues is published in Scientific Reports.