How dog DNA is helping scientists understand the aging process

When Brianah McCoy began her PhD at Arizona State University, she knew she wanted to study the biology of aging. What she didn’t know was that dogs would be her subjects and that her research would go on to uncover compelling insights in the field of aging science.

McCoy joined ASU’s Molecular and Cellular Biology program in 2020, and her doctoral work found its home in the lab of Noah Snyder-Mackler, one of the principal investigators for the Dog Aging Project—a massive, nationwide study tracking the lives, health and aging patterns of thousands of companion dogs. McCoy was immediately drawn to the project. “It just made so much sense. Dogs live with us, eat with us, age with us. They're exposed to the same environments, and they develop similar diseases.”

Over the course of her PhD, McCoy helped illuminate how genetic and environmental factors influence biological aging in dogs, often in ways that mirror human aging. One of her major findings? Dogs don’t all age the same way—even if they’re the same chronological age.

“We found that biological aging is influenced by things like social support and home environment,” she explained. “Two 10-year-old dogs might look the same on paper, but one might be experiencing significant cellular decline while the other is healthy and active. That’s something we also see in people."

McCoy’s research also uncovered clear disparities between dog breeds, especially when comparing large and small breeds. Large dogs, like Great Danes, not only age faster but seem to follow entirely different molecular aging pathways than small dogs. “It’s not just about size or growth hormones. The biology is different,” she said. “Smaller breeds are more prone to things like heart disease, while large breeds tend to suffer earlier from musculoskeletal decline.”

The implications of this work reach far beyond veterinary science. Because dogs live in human environments and develop many of the same age-related conditions, McCoy’s findings are informing broader studies on aging, healthspan and disease prevention. Her research even touched on public health themes—such as social isolation and companionship, which became highly relevant in the wake of the pandemic.

“We found that dogs with other canine or human companions were more active, healthier and had better aging outcomes,” she said. “It mirrors what we know about people, that connection and community are critical to staying healthy as we age.”

Throughout her time at ASU, McCoy was not just collecting data—she was also helping change how aging research is approached. The Dog Aging Project includes collaborators from multiple institutions, but much of McCoy’s dissertation work was at the forefront of connecting dog biology to human health. And the public has taken notice. Her work was widely shared in the media, especially studies highlighting how everyday factors like taking your dog to the park or having a multi-dog household could impact a pet’s longevity.

Upon graduating this May, McCoy will start as a postdoctoral fellow at the University of North Carolina, Chapel Hill, and is shifting her focus from canine to human subjects. She’s studying how reproductive history and hormonal factors influence biological aging in women—a topic long neglected in medical research. “We’ve based so much of our health data on male biology,” she said. “It’s time to look closer at how aging uniquely impacts women across their reproductive lifespan.”

Still, her years studying dogs will remain a core part of her scientific identity. “I never thought I’d be working on dogs,” she said. “But they turned out to be the perfect model for asking really big, human-centered questions about health and aging.”