Could a dog’s true age be revealed not by its birth date, but by the bacteria living in its gut? A new international study led by Prof. Elhanan Borenstein of Tel Aviv University has mapped the gut microbiomes of 922 pet dogs and found that their bacterial populations change significantly with age, diet and behavior.
The researchers also developed an artificial intelligence model capable of estimating a dog’s age based on the composition of its gut microbiome, a first step toward what they describe as a new kind of biological clock. The study, published in Nature Communications, was led by doctoral students Tal Bamberger, Efrat Muller and Yadid Algavi from Borenstein’s laboratory.
Scientists have increasingly recognized the gut microbiome, the vast community of microorganisms living in the digestive system, as an important factor in digestion, immune activity, metabolism and aging.
While much of that research has focused on humans, pet dogs offer researchers a particularly useful model. They share homes, environmental exposures and, in many cases, lifestyle patterns with people, but they age much faster. That allows scientists to study biological changes linked to aging over a shorter period and compare them with processes seen in humans.
The study found that age was one of the strongest factors shaping the composition of dogs’ gut microbiomes. As the animals grew older, the diversity of their gut bacteria declined and the overall bacterial population gradually changed. Researchers identified dozens of bacterial species whose abundance shifted with age, echoing patterns previously observed in humans.
Using those findings, the team developed a machine-learning model designed to estimate a dog’s biological age from its gut bacteria. The model was trained using data from dogs included in the study and then tested on a separate group. Researchers said it was also able to predict age significantly in the external group, strengthening the possibility that microbiome composition could eventually serve as an aging marker. The researchers cautioned that the work represents an early stage in developing such a tool.
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The study also found clear differences in gut bacteria depending on what the dogs ate. Dogs fed commercial food had different microbiome profiles from those eating homemade diets. Certain behaviors also appeared to influence bacterial composition, including coprophagy, the consumption of feces.
Researchers also identified links between gut bacteria and a range of measurements in blood and urine tests. Although the effects were generally modest, they were consistent. In many cases, microbiome composition explained more of the variation in laboratory results than factors such as breed, sex or weight.
The findings could eventually have practical implications for veterinary medicine. A better understanding of how the gut microbiome changes throughout a dog’s life could help veterinarians identify age-related biological changes earlier, tailor diets or treatments to individual animals and develop new ways to support healthier aging.
The researchers also hope the work may contribute to human medicine. Because pet dogs share many environmental conditions and exposures with their owners, studying them could offer insights into age-related disease and help scientists explore strategies for promoting healthy aging in people.
“Pet dogs are an exceptional research model for understanding the connection between gut bacteria and aging,” Borenstein said. “Our study creates, for the first time, a broad reference map of gut bacteria in dogs and allows us to understand how they change throughout life.”
Prof. Elhanan Borenstein Photo: Chen Galili“In the future, this kind of knowledge could help both in developing new tools to protect dogs’ health and in understanding aging processes in humans,” he added.
The project is still in its early stages. Because the dogs are being followed over time as part of the Dog Aging Project, researchers will eventually be able to track changes in their microbiomes throughout their lives and examine how those shifts relate to disease, healthy aging and longevity.
The database created through the study also contains genetic, metabolic and epigenetic information. Researchers say it could become a valuable resource for scientists, veterinarians and aging specialists seeking to understand how the microbiome interacts with health and aging in both dogs and humans.