How dogs can help us learn about human ageing

Scientists find clues in kidneys and gut of pets that may eventually slow process in humans

Researchers for the Dog Aging Project in the United States began enrolling dogs in a long-term study of ageing in 2020 (Getty Images)

Dog owners often treat their pets like miniature humans – and now scientists are studying canines in the same way to discover more about the mystery of ageing in people.

They suspect a clue to the varying rates at which both dogs and humans age may lie in the kidneys and the gut.

In 2020, researchers for the Dog Aging Project in the United States began enrolling dogs in a long-term study of ageing, ending up with about 50,000 canines volunteered by their owners.

The project was designed to identify patterns of ageing and how they are shaped by genetic and environmental variations.

The pets were thought to be ideal models for the research because they have similar genetic diversity, diseases and homes to humans. “Dogs vary tremendously, not only in size, shape, and behaviour, but also in their patterns of aging,” a new study by the project says.

The researchers said dogs’ relatively short lifespans give them a chance to see the effect their discoveries will have on both dog and human health in their own lifetimes.

After analysing blood samples from nearly 800 dogs they have found that about 40 per cent of the small molecules in dogs’ blood change with age.

“These molecules, known as metabolites, are basically the building blocks of life,” said Daniel Promislow, a scientist, co-director of the Dog Aging Project and senior author of the study, published in the journal Aging Cell.

Digesting food can create the amino acids linked to ageing (AFP via Getty Images)

“They serve as the raw materials for forming proteins, DNA and other cellular components, and play a critical role in keeping cells alive.”

The researchers found that one type of metabolite, called post-translationally modified amino acids (ptmAAs), appeared strongly linked to ageing in dogs of all breeds, sizes and sexes.

Bacteria in the gut can create the amino acids as food is digested.

As dogs and humans age, the kidneys become less effective, and the study authors found that as kidney function declines, the amino acids build up, possibly explaining why some dogs age more healthily than others – and offering clues for humans, too.

The researchers plan to follow changes in metabolites in the same dogs over several years and will try to identify gut microbes that might change in abundance with age.

They also want to look at information from owners to see whether changes in muscle mass — a common phenomenon in both ageing dogs and people — are linked to the amino acids.