In February 2024, when Boo the Whippet became the first patient in a clinical trial of a life-extending drug for senior dogs, a call was put out for more canines. A milestone was reached in the ongoing trial when 10-year-old Miniature Dachshund Winston became the thousandth dog to enrol.
Editor’s note: Readers often ask us for follow-ups on memorable stories. What has happened to this story over the years? This article was originally published in February 2024 but has been re-edited and updated with new information current as of June 5, 2025. Enjoy!
The STAY study, a clinical trial testing the effectiveness of a life-extending drug, LOY-002, on senior dogs, is now well underway. Results from a trial of LOY-001, the drug’s predecessor, which was made for large-breed dogs, were so encouraging that they paved the way for Loyal, the biotech company that makes the drug, to start a new trial for dogs of nearly every size.
Large dogs may only live seven to eight years, compared with the average lifespan of little ones, who can live for up to 20 years. Selectively breeding large- and giant-breed dogs has resulted in them having levels of IGF-1, a hormone that drives cell growth and is part of the longevity pathway in animals and humans, up to 28 times higher than those of small dogs. Loyal’s drug inhibits IGF-1 overexpression and extends a dog’s healthy lifespan.
After the LOY-001 trial, the US Food and Drug Administration’s (FDA) Center for Veterinary Medicine agreed that its data supported a “reasonable expectation of effectiveness.” It is the first time the FDA has accepted a drug to extend the lifespan of any species by reducing age-related disease. The announcement was, understandably, enthusiastically embraced by large-breed dog owners and the press.
Big news for big dogs: What the press is saying about Loyal’s recent announcement
In February 2024, Loyal began testing LOY-002, a daily beef-flavored pill designed to extend a healthy lifespan in senior dogs of all but the smallest sizes. Boo, the 11-year-old Whippet, was the first to be dosed as part of the STAY study. Then the howl went out across the US to recruit more participants. In April 2025, the milestone of 1,000 dogs was reached when the trial enrolled Winston, a 10-year-old Miniature Dachshund from Indiana.
“The STAY study has been very exciting for myself and my colleagues because the prospect of helping our dogs live longer, healthier lives is the reason we joined the veterinary field,” said Dr Amy Smith, the vet who enrolled Winston. “Owners participating in the STAY study enjoy making a difference in the well-being of dogs now and in the future.”
Winston’s addition makes the STAY study the largest clinical trial in veterinary history. But, even more dogs are needed. Expanding the study’s sample size is scientifically important because it’s more likely that the true effects of LOY-002 will be observed in a larger, more diverse group.
The goal is to get to 1,300 dogs, and Loyal plans to finish recruiting the final 300 in the next few months. To check if your dog is eligible to join the STAY study, go to the Loyal website.
Source: Loyal
A version of this article was originally published in February 2024.
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