A New Drug Aims to Extend the Life Expectancy of Large Dogs

It goes without saying that, in a perfect world, all dogs would live forever — regardless of breed. But, as it is, there is major variation in the expected lifespan of different pups. As most big dog parents are all too aware, big dogs generally don’t live nearly as long as small ones. Saint Bernards, for example, are estimated to live between five to eight years, while Chihuahuas can live 15 to 20. 

Most pet parents would give anything to add a few more years to their pups’ lives — and that’s exactly what biotech company Loyal aims to do. Their experimental drug, LOY-001, targets a hormone in large dogs that may contribute to their increased mortality. Today, Loyal announced that LOY-001 has been determined by the Food and Drug Administration (FDA) to have a “reasonable expectation of effectiveness,” reports Wired. This means that if Loyal can prove the injection is safe and can be reliably manufactured, the drug may soon be available by prescription. 

How the drug works

According to The New York Times, LOY-001 is designed to modulate insulin growth factor-1 (IGF-1), a hormone that plays a role in determining a dog’s body size. Since small dogs generally live longer than large dogs, some scientists think IGF-1 may influence both growth and aging. Inhibiting IGF-1 has increased the lifespan of worms, rodents, and flies; in humans, the lowest mortality is associated with a midrange of IGF-1. 

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The experimental drug is an injection given to dogs every three to six months. So far, the only side effects have been temporary gastrointestinal distress in the days following the injection. There have been no serious side effects reported.   

Loyal’s research shows that LOY-001 is effective in reducing IGF-1 levels in dogs, as well as curbing increases in insulin that occur when dogs age. That doesn’t necessarily mean that the drug can extend dog lifespans, though; so far, no data has shown that LOY-001 lengthens lives.

What does it mean to increase a dog’s lifespan?

While Loyal aims to eventually prove the drug can add one year to a dog’s lifespan, founder Celine Halioua is clear that the company is not aiming for immortality. “I don’t know of anybody who is developing a drug that’s gonna rapidly extend lifespan. I really think of it more as rounding out the curve,” Halioua said on an episode of the podcast Have a Nice Future. “So if you think of it as if you have age on the x-axis and quality of life on the y-axis, it’s kind of flat for a while and then it starts declining until you get to that period of end of life. The idea of an aging drug really is gonna be more about extending the number of years that somebody is in that healthy productive state.” 

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To those who think that increasing a dog’s lifespan is unnatural, Halioua pushes back. “We already did play God by creating dog breeds. Dog breeds are not a natural phenomenon,” she said.

With that in mind, Loyal doesn’t look at the early aging of large dogs as a given. “We see the short lifespan of big dogs not as inevitable, but as a genetically-associated disease caused by historical artificial selection, and therefore amenable to targeting and treatment with a drug,” Dr. Brennen McKenzie, the company’s director of veterinary medicine told Business Insider. In other words, they view LOY-001 as a treatment for a complication caused by years of deliberate dog breeding. “Fundamentally, it’s just a medicine like a cancer drug,” Halioua said in the podcast.

Next steps for Loyal

Before the drug can hit the shelves, Loyal has to prove to the FDA that it can be reliably manufactured and is safe for pets. This will allow them to be granted conditional approval, which means the drug can be sold by prescription, while Loyal collects additional data and applies for full approval. Loyal hopes to receive conditional approval in 2026. 

Loyal is planning a large study that will take place in 2024 or 2025 and enroll about 1,000 large dogs of at least seven years of age; these dogs will receive either LOY-001 or a placebo. It will be several years before the real effects of LOY-001 are clear. 

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Implications for future research 

“The implication for other species, including humans, is pretty profound,” Dr. Linda Rhodes, an animal health industry expert and a consultant for Loyal, told Wired. If it gains approval, the drug would be the first approved by the FDA to focus on delaying aging rather than targeting a specific condition. Rather than waiting for symptoms to occur, LOY-001 begins treating maladies associated with aging preventatively. 

Halioua agrees that Loyal’s research is relevant to future research on human mortality. “The things we’re targeting are not dog-specific,” she said. “We just think they are likely to be very helpful to dogs and to helping them extend their lifespan, and dogs, again, are a very good representative of people. So if it works in a dog, I think there’s strong evidence to believe it would work in a human, too.”