The health benefits of having a pet — especially a dog — are well-established. Dog owners have been shown to live longer, healthier lives than people without pups, in part because caring for a dog encourages physical activity. And pets of all types have been shown to lower their owners’ stress levels and improve their mental health.
But a new research letter published in JAMA Surgery offers a look at a potential downside of pet ownership. Among older adults, fractures linked to dog-walking are surprisingly common and growing more frequent, according to the research.
Researchers examined data from the National Electronic Injury Surveillance System, which logs injuries reported by patients visiting a nationally representative group of 100 U.S. hospital emergency rooms. In 2004, almost 1,700 adults ages 65 and older went to the emergency room for fractures related to walking leashed dogs, they found. By 2017, that number had risen to almost 4,500.
Fractures can occur as the result of falls or dogs lunging while they’re leashed, the authors write — and they have some ideas about why the numbers have shot up since 2004. Dr. Jaimo Ahn, an associate professor of orthopedic surgery at the University of Pennsylvania School of Medicine, says the reasons behind the uptick are likely positive, even if the end result — more injuries — is not.
“People intuitively know many of the benefits of animal companionship,” Ahn wrote in an email to TIME. “Not surprisingly, pet ownership has increased over time, including among the elderly, who are living longer and taking efforts to live healthier — all good things.”
Still, the research suggests that the risks of pet ownership shouldn’t be ignored, especially for older adults. Almost 30% of the injured seniors in the paper were admitted to the hospital, and nearly 20% suffered hip fractures. This type of fracture is “associated with long-term decreases in quality of life and functional capabilities, as well as mortality rates approaching 30%,” the authors write.
“As we get older, we should consider both the risks and benefits of the physical activity we desire and make sure we’re safely and thoughtfully up for the challenge,” Ahn says.
Dog-walking offers seniors a valuable opportunity to assess — and, if necessary, improve — their own strength, walking ability and overall well-being, he says, as well as their dog’s behavior.
“There are so many benefits from pet ownership, but just like everything else, there are negatives to potentially consider,” Ahn says.
Correction, March 29
The original version of this story misstated the year in which the study began. Nearly 1,700 adults went to the emergency room for fractures in 2004, not 2014.