Monitoring the hearts of nearly 200 Japanese people, scientists found those who had a pet – whether furry, scaly or feathered – had greater heart rate variability than those who didn't.
Dr Erika Friedmann, a professor at the University of Maryland School of Nursing, said the study is a step forward from what is already known about the connection between pet ownership and a person's heart health – although it's not clear how to explain the link.
"Here we're moving that into people's daily lives, and that's what's so exciting," said Dr Friedmann, who wasn't involved in the new work, but has done similar research. "It really goes beyond what happens in a ten minute period in the lab."
For the new study, researchers at Kitasato University in Kanagawa, Japan, monitored 191 people with diabetes, high blood pressure or high cholesterol over 24 hours. The researchers also asked them about their daily activities and whether or not they owned a pet.
About 40% owned a pet, but other than that the participants were similar, Naoko Aiba and colleagues reported online in the American Journal of Cardiology.
Each person wore a heart monitor for 24 hours. For pet owners, about 5% of their heart beats differed by 50 milliseconds in length; for non-pet owners, that number was 2.5%.
So far, nobody knows what's causing the difference between the two groups – It could be due to the pets somehow, or it could be there are differences between people who choose to get a pet and those who don't.
"My guess is that pets are a form of social support, hence stress reduction, and they can satisfy some but not all social companionship needs," Dr Judith Siegel, a professor at the UCLA School of Public Health, told Reuters Health by email.
But she added that earlier research on the topic has yielded conflicting results.
"I don't think anyone has a good handle yet on why these discrepancies exist," said Dr Siegel, who was not involved with the new study.
The Japanese researchers also caution that they only looked at one day in the person's life. And other factors need to be considered in future research, such as potential differences between different types of pets.
Past research has shown that aerobic exercise can improve heart rate variability. As for whether a person should get a pet to protect their heart, Dr Friedmann said that's OK as long as they want one anyway.
But, she adds, "It's not going to cure someone."
(Andrew M. Seaman, Reuters Health, February 2012)