Could This Drug Help Our Dogs Live Longer? Researchers Are Testing Rapamycin to Find Out

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It may sound far-fetched or too good to be true, but researchers are investigating whether a pill could help our dogs live longer.

Staff at the University of Washington's Dog Aging Project may be helping us get one step closer to making this dream a reality. The team is running a nationwide study involving almost 600 dogs, testing the life-extending potential of the drug rapamycin.

Usually, humans take rapamycin. It's authorized by the U.S. Food and Drug Administration (FDA) for humans who've undergone organ transplants. The drug suppresses the immune system to prevent it from attacking donated organs. But rapamycin, also known as sirolimus, may also help slow the canine aging process, potentially adding years to our dogs' lives.

Could Our Dogs Live 3 Years Longer?

The study's lead researcher, Matt Kaeberlein, PhD, tells Daily Paws rapamycin targets the biology of aging in every living thing it's been tested in, from single-celled yeast to mice. The potential key: smaller doses than what humans take to prevent transplant rejection.

"Rapamycin seems to have the ability to 'reset' immune function by reducing the increase in chronic inflammation that goes along with aging," Kaeberlein says. "This also seems to have benefits beyond the immune system in all sorts of tissues and organs."

In mice, rapamycin seems to reverse age-related functional declines in the heart, brain, ovaries, and oral cavity, Kaeberlein says. It also appears to boost the immune system's ability to detect cancers and fight off viruses like the flu and COVID-19.

In the current study, researchers speculate that the low doses of rapamycin may increase the lifespan of dogs by up to three years. Kaeberlein says this estimate is based on experiments in laboratory mice, where rapamycin increased average lifespans by up to about 25 percent.

If that percent is applied to a dog with a 12-year lifespan, the pooch taking rapamycin could theoretically live to 15. Of course, the drug has been tested on mice, so it's unknown whether it will have the same effect on dogs, Keaberlein says.

As if the prospect of a new life-extending drug for dogs wasn't exciting enough, it might also work for aging cats because the biology of aging is so similar among many species, Kaerberlein says.

Questions Remain

So this is certainly promising, but many questions remain regarding rapamycin's impact on aging, including which dogs can take it and when.

Kaeberlein says he's not aware of any biological reason that would make dogs more or less likely to benefit from it, though some dogs may react differently to rapamycin because of their genetics. As for when to start taking it, Kaeberlein says the sweet spot might be around 6 or 7 years old for larger dogs and 9 or 10 years old for smaller dogs—based on the mice experiment.

RELATED: The Real Way to Calculate Your Dog's Age in Human Years

And even if the study proves successful, it's unclear how long it will be before you can get a hold of rapamycin for your aging pets (or yourself).

Kaeberlein says their trial won't directly lead to rapamycin's FDA approval for longevity in dogs, although it certainly could help. He adds that the study didn't seek FDA approval for rapamycin because it's already approved for human use. Plus, physicians and veterinarians can already prescribe it for off-label (non-approved) uses.

But even with all these unknowns in play, Kaeberlein indicates there's good reason to be optimistic.

"If our trial shows compelling evidence for beneficial effects and little in the way of side effects, I suspect many veterinarians will become more comfortable prescribing it for owners who request it," he says.