DNA study offers clues to why big dogs age faster

Scientists have identified changes in DNA regulation that could help explain why large dogs tend to age faster than small ones, giving researchers a clearer direction for studying canine longevity.

An international team led by Arizona State University researchers analysed DNA samples from hundreds of dogs in the Dog Aging Project. Published in Science, the study examined chemical marks that help control gene activity without changing the underlying DNA sequence.

These marks also help keep “jumping genes” in check. These are stretches of DNA that can move or copy themselves into other locations. If their controls weaken, some can become active and potentially cause harmful changes.

In giant breeds, marks associated with one family of jumping genes, called LINE-1, disappeared at an annual rate about 35% faster than in small breeds. That offers a possible molecular explanation for the familiar link between larger size and shorter canine lifespans.

The team also developed a DNA-based aging clock that estimated dogs’ chronological ages with an error of roughly one year. Such tools could help researchers identify animals aging faster than expected, although they cannot precisely predict an individual pet’s lifespan.

The findings do not establish whether the DNA changes help drive aging or result from it, and the study did not test a treatment to extend dogs’ lives. They do, however, identify a promising focus for further research.