'Let's grow old together': A drug to slow aging in dogs may be on the way

A graying muzzle, clouding eyes, a slower gait — these are the signs of aging that every dog owner eventually faces. For a long time, such changes were accepted as a natural, inevitable process. But scientists now say that is no longer the whole story. Rather than simply watching aging unfold, they believe it can be detected early and its progression slowed.

According to the Wall Street Journal on Thursday, Brennen McKenzie, chief veterinary officer at US biotech company Loyal, said he is developing a new drug to slow aging in dogs. The most prominent conversation in veterinary medicine right now, he said, is "not about responding after aging has begun, but about preventing it in advance."

For more than a decade, researchers have focused on identifying biological markers that can predict how healthily a dog is aging — and how much longer it is likely to live.

A recent US study analyzing blood samples from 937 dogs found that concentrations of certain metabolites in the blood were closely linked to the risk of death during the follow-up period. Daniel Promislow, a professor at Tufts University who led the research, said a blood test alone can predict a dog's risk of death to a meaningful degree. He predicted that affordable, simple molecular tests will eventually allow veterinarians to anticipate the likelihood of disease before it develops.

Another area of research focuses on measuring a dog's "biological age" — a measure based on physical condition rather than chronological age. In 2024, researchers at Nestlé's Purina analyzed health records and blood tests from 829 dogs and found that those whose biological age exceeded their actual age by more than a year faced a higher risk of death. Researchers hope such markers will enable tailored care aimed at extending healthy lifespan.

Drug development aimed at slowing the pace of aging is also advancing rapidly. Researchers with the US Dog Aging Project are studying whether low doses of the immunosuppressant rapamycin can improve heart health, physical fitness, cognitive function and longevity in dogs. Rapamycin has already been shown to extend lifespan in mice. In the current study, dogs receive the drug once a week for a year while researchers monitor their progress.

The team described the work as "the first large-scale study to validate a drug that slows biological aging and extends healthy lifespan in a real-life environment," and said that if results are positive, the drug could be prescribed to healthy dogs as well.

Loyal aims to launch what would be the world's first drug to delay aging in dogs next year, pending conditional approval from the US Food and Drug Administration. The drug works by improving insulin sensitivity — the company says declining insulin function can raise the risk of cancer and dementia while accelerating muscle loss.

Loyal is also developing two additional drugs that regulate IGF-1, a growth hormone. The company believes large dogs have shorter average lifespans than small dogs because their IGF-1 levels remain elevated for longer, and expects that lowering IGF-1 after a dog has finished growing could extend the lifespan of larger breeds.

mokiya@heraldcorp.com