Why do some individuals remain healthy into old age while others develop multiple diseases decades earlier? The answer may be hiding somewhere unexpected: our dogs.
Scientists increasingly see companion dogs as valuable models for understanding human aging. Unlike laboratory animals raised under highly controlled conditions, pet dogs live in the real world. They share our homes, environments and many lifestyle exposures and they develop naturally occurring conditions such as cancer, arthritis, obesity, diabetes and cognitive decline.
Dogs age faster but in surprisingly similar ways
Dogs have much shorter lifespans than humans, but their aging biology shares important features with ours. Their risk of chronic diseases rises with age, and many causes of illness and death show similar age-related patterns to those observed in people.
There is also enormous natural variation between breeds. Some dogs live considerably longer than others, creating an unusual opportunity to investigate how genetics, body size, environment and lifestyle influence longevity.
This variation can act almost like a natural experiment.
What can their blood tell us?
A major 2026 study involving thousands of dogs from the Dog Aging Project found that several blood traits were associated with mortality risk. Researchers also found genetic connections between canine and human blood traits, suggesting that some biological pathways involved in aging have been conserved across both species.
Another 2026 study compared molecular markers of mortality in dogs and humans and found shared biomarkers associated with survival. The researchers used data from more than 50,000 companion dogs, providing evidence that some biological signals of aging may transcend species.
Even DNA itself provides clues. Research comparing dogs and humans has identified age-related changes in DNA methylation, an epigenetic process that influences gene activity. These changes can be used to estimate biological age and reveal similarities in how mammals progress through physiological aging.
Could dogs help us live longer?
That is the ultimate goal but researchers are not suggesting that dogs can simply tell us how long a person will live.
Instead, studying dogs could help scientists identify biomarkers and biological pathways associated with healthy aging, test potential interventions more efficiently, and understand why some individuals remain healthier for longer.
Projects such as the Dog Aging Project are following tens of thousands of companion dogs over time to investigate how genetics, environment, behaviour and health interact throughout aging.
The lesson may extend beyond dogs themselves. If two species living in very different bodies show similar molecular signatures of aging, those shared signals could point toward something fundamental about what makes organisms age and what might allow them to age more healthily.
So perhaps our dogs are not just companions.
They may also be living laboratories for one of biology’s biggest questions: why do some bodies age better than others?
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