No dog longevity drug is approved or on sale anywhere. The closest is Loyal’s LOY-002. It has passed two of the three FDA reviews needed for conditional approval (Report). The 1,300-dog trial that tests whether the pill really extends life has not reported (Report).
You may have seen this called the first drug approved to extend lifespan. That is ahead of the facts. What the FDA has actually cleared is narrower, and worth getting right.
What the Dog Longevity Drug Is
LOY-002 is a daily tablet made by Loyal, a US company also known as Cellular Longevity. It is aimed at dogs aged 10 and older that weigh at least 14 lb, or about 6.4 kg (Announcement).
The idea is easy to say and hard to do. Loyal calls it a caloric restriction mimetic. In plain terms, the pill should give a dog some of the effects of eating less, without the dog eating less (Announcement). The company says it works on the way an aging body handles food and energy, not on one disease. Its stated target is insulin. It aims to lower insulin in the blood and help the body respond to it better (Overview).
Loyal has not said what the active ingredient is. Its own material for vets says the drugs and how they work stay confidential during development (Overview). So “caloric restriction mimetic” is the company’s label for a type of drug. It is not a disclosed target.
This is the senior-dog program, and people mix it up with a different one. Loyal also has LOY-001 and LOY-003, two separate drugs for large and giant breeds. Those aim at IGF-1, a growth signal, and they have their own age and weight rules (Overview). LOY-002 does not target IGF-1, and small dogs can take it.
No vet can prescribe it today (Report).
What the FDA Has Cleared
Animal drugs in the US are handled by the FDA’s Center for Veterinary Medicine. A company files its case in sections, and the agency accepts them one at a time. LOY-002 needs three of them for conditional approval.
The first covered the reasonable expectation that the drug works. That one was announced in February 2025 (Announcement). The second covered safety in the dogs themselves, announced on 13 January 2026 (Report). Manufacturing is the third, and Loyal says it is still working on that one (Announcement).
The safety package was ordinary drug-safety work. Loyal says dogs were given one, three and five times the intended dose, with no meaningful harm (Announcement). It added real-world data from more than 400 dogs given LOY-002, some for up to a year. None of that data is published. The agency accepted the section, which is not the same as vouching for the findings.
Conditional approval is a real approval, but the bar is lower than full approval. For an animal drug, the company must show that it is safe and made to full-approval standards. On whether it works, it only has to show a reasonable expectation (Guidance). The full bar, called substantial evidence, still has to be met later (FDA).
The clock is short. A conditional approval lasts one year. It can be renewed once a year for up to four more years (FDA). With all four renewals, the company gets up to four and a half years to hand in the missing evidence. Miss that deadline and the approval ends at once. The drug goes back to being unapproved (FDA). Each renewal also depends on real progress toward the full bar (Guidance).
There is a genuine first here, and it is a regulatory one. The faster path is only open to animal drugs that pass two tests. The drug has to treat a serious condition or an unmet need. Proving that it works also has to be hard, needing a long or difficult study (Guidance). Regulators have not treated aging itself as something a drug can be aimed at. Loyal calls the safety acceptance a first for a lifespan drug in any species, and the vet trade press has repeated that (Report). So the path has changed. That still says nothing about whether this pill works.
Why Big Dogs Die Young
Great Danes rarely reach 10. Chihuahuas often pass 15. That gap is one of the odder facts in animal biology. Within a species, bigger animals usually live longer.
Much of the size difference is genetic, and one gene does a lot of the work. Researchers read the DNA of 3,241 dogs from 143 breeds (Study). One version of the IGF1 gene showed up in nearly every small breed and almost no giant ones. In a much smaller group from a single breed, dogs with two copies of that version had less IGF-1 protein in their blood.
Blood tests in living pets fit the same pattern. In more than 140 dogs across 43 breeds, IGF-1 was higher in heavier dogs and fell with age (Study). That study did not measure how long any of them lived.
Lifespan has been counted too. A study of more than 40,000 dogs from 118 breeds found that heavier breeds live shorter lives (Study). Each extra kilogram of average breed weight went with about 26 fewer days of life. Across the whole range of breeds, that adds up to roughly four and a half years. Size explained more than half of the gap between breeds, and genetic variety explained a little more.
Growth signaling was the obvious first place to look, and that is what Loyal’s large-breed program does (Overview).
LOY-002 is not that drug, and this is where the confusion starts. Loyal’s own study of 451 pet dogs found that higher insulin went with more frailty and worse quality of life (Study). IGF-1 was measured in the same dogs and showed no such link once body weight was allowed for. The authors work for Loyal. The study was also a single snapshot in time, so it cannot show cause. It does point at insulin rather than growth.
The Calorie Study Behind It
The strongest evidence for the idea behind LOY-002 has nothing to do with LOY-002. It comes from a long study of dog food.
Purina researchers raised 48 Labrador retrievers from seven litters. The dogs were paired by sex and weight. A coin flip decided which one of each pair ate less (Trial). From eight weeks old, the restricted dog got 25% less of the same food than its pairmate had eaten the day before. That continued for life.
Half of the restricted dogs lived past 13.0 years. In the group that ate normally, half lived past 11.2 years (Trial). The gap is 1.8 years, or about 16% longer. The oldest dogs in each group ended up at similar ages. The gain sat in the middle, not at the ceiling.
Disease arrived later too, and arthritis was the most common problem. The typical restricted dog first needed long-term treatment for it at 13.3 years, against 10.3 years in the normally fed dogs (Trial). For any long-term condition, the ages were 12.0 and 9.9 years. Hip arthritis showed on X-rays in 42 of every 100 normally fed dogs by age two, against 4 of every 100 restricted ones (Review).
People overstate the cancer result. Eleven dogs died of cancer. The five restricted ones died at an average age of 11.6 years, and the six others at 9.7 years (Review). With so few dogs, the authors said chance could explain that gap. A later look at the same dogs found the causes of death were broadly similar in both groups (Study). Eating less changed when the dogs died. It did not change what they died of.
The insulin numbers are what tie this study to LOY-002. Restricted dogs carried far less body fat, and had lower insulin and glucose in the blood (Trial). Dogs above 25% body fat responded less well to their own insulin. That in turn predicted how long they lived and how much long-term disease they got (Review).
That is the effect LOY-002 is trying to copy. Ask an owner to keep a dog mildly hungry for 13 years and almost nobody manages it. A pill that copies part of the same change would be far easier to stick to. That study tested food, though, not a drug.
Why Dogs Age Like We Do
Dogs are a serious model for human aging, and the reasons are practical. They live in our houses and breathe our air. They eat food we buy, and they see doctors inside a system much like ours (Study).
A lab mouse in a sterile cage shares none of that. Where you live is one of the biggest drivers of how you age, and a clean room cannot copy it (Study).
Dogs also get our diseases. A comparison of 112,375 people and 37,480 dogs found that cancer caused almost the same share of deaths (Study). It was 25 of every 100 human deaths and 27 of every 100 dog deaths. Obesity, arthritis, thyroid disease and diabetes cluster together in older dogs much as they do in older people. In clinic records for 2,586 dogs, the number of diagnoses climbed steadily with age (Study). That pile-up is what aging looks like in a clinic.
And they age fast. The Dog Aging Project team puts it at roughly seven to ten times quicker than we do (Study). That is why this research is possible at all. A human lifespan trial would outlast the researchers running it.
A good model is still a model. The clearest break is the heart. Dogs almost never get the clogged-artery disease that kills so many people. Deaths from blood vessel disease are far more common in humans (Study). Whatever a drug does for an old dog’s heart may not carry across.
What the STAY Trial Measures
STAY is the study that decides this. A coin flip decides which dogs get LOY-002 and which get a dummy tablet. Neither the owners nor the vets know who got what (Trial).
Loyal says it enrolled 1,300 senior dogs, screened from more than 1,500, across 72 vet clinics in the United States (Announcement). Sign-ups closed in July 2025, and Loyal calls it the largest clinical trial ever run in veterinary medicine (Report).
The trial measures more than survival. It compares lifespan, health and quality of life against the dummy-tablet group (Trial). Owners fill in quality-of-life surveys throughout, and dogs are seen six times in the first year.
As of April 2026 the study was about two and a half years in, and it runs at least four years (Report). There was no result on whether the drug works. So every claim that LOY-002 extends a dog’s life is an expectation today, not a finding.
If conditional approval is granted, the drug could be sold while this evidence is still being gathered (Report). That is what the pathway is for. It is not a way around the evidence, but it does mean the evidence lands after the sale.
What It Does Not Prove
The big-dog IGF-1 story does not transfer to people, and that is the first limit. Human IGF-1 peaks around puberty and drifts down with age. In one study of 184 people in their nineties, women with lower IGF-1 lived longer (Study). No such link showed up in the men, but only about 45 of them were men. That is too few to rule an effect out. A pooled analysis of 19 studies and 30,876 people found no simple rule either (Meta-analysis). Both low and high IGF-1 went with a higher chance of dying. The risk was about a third higher at the low end and about a quarter higher at the high end. Middle levels did best.
The direction also depends on which disease you ask about. Among 369,711 UK adults followed for more than 12 years, dementia and stroke were both more common at the low and the high end (Study). Parkinson’s disease became steadily more common as IGF-1 rose. There is no single good level.
The second limit is simpler. Nobody is getting this pill. LOY-002 is a veterinary drug, dosed for dogs, with no human trial. Nothing here is a shortcut to a human longevity drug.
The third limit is that LOY-002 is not the only test running. The Dog Aging Project’s TRIAD trial gives weekly low-dose rapamycin or a dummy tablet to healthy dogs aged 7 and over. Its main measure is how long the dogs live (Protocol). That drug works a different way, and those dogs are younger. Its target is 580 dogs, and a September 2025 review reported about 210 signed up by then (Review). Each dog is in the study for three years, so a result is still years off. Earlier rapamycin trials in dogs were small: 24 dogs for 10 weeks in 2017 (Trial), and 17 dogs for six months in 2023 (Trial). The second did not see the earlier heart findings again. It also stopped enrolling early, so it was too small to rule out a modest effect. Neither measured lifespan. Our piece on low-dose rapamycin and longevity covers what that drug does and does not show in people.
Frequently Asked Questions
Is there a dog longevity drug you can buy yet?
No. No dog longevity drug is approved or on sale anywhere. LOY-002 is the closest. It still needs its manufacturing section accepted before conditional approval is even possible (Report).
Is LOY-002 FDA approved?
Not yet, and the goal is conditional approval rather than full approval. Two of the three sections have been accepted, announced in February 2025 and January 2026 (Report). For an animal drug, conditional approval means it is safe and properly made, with a reasonable expectation that it works (FDA). Full approval needs substantial evidence that it works, and STAY is still collecting that.
Which dogs would be eligible for LOY-002?
The target label is dogs aged 10 and older that weigh at least 14 lb, roughly 6.4 kg (Announcement). Small breeds count, which is one way it differs from Loyal’s large-breed drugs. LOY-001 is an injection for dogs 7 and older above 40 lb. LOY-003 is a daily pill for dogs 5 and older above 60 lb (Overview).
How much would LOY-002 cost?
Neither the price nor a launch date has been published. Loyal has said conditional approval is what would allow a market launch (Announcement). Reporting notes that the drug could reach the market before STAY finishes (Report). Treat any figure you see as guesswork.
Could a drug like this work in humans?
Unknown, and nothing here shows it. There is no human trial of LOY-002 and no published plan for one. Human evidence on the growth pathway behind the large-breed drugs is genuinely mixed. Both low and high IGF-1 have been linked to a higher chance of dying (Meta-analysis).
Key Takeaways
- Not approved, and not for sale. Two of the three FDA sections are accepted, and manufacturing is still outstanding (Report).
- Conditional approval is the lower bar. It means safe, properly made, and a reasonable expectation of working. It lasts one year and can be renewed up to four times (FDA).
- LOY-002 aims at insulin, not IGF-1. It is for senior dogs. The IGF-1 work is a separate program for large breeds (Overview).
- The real evidence base is a food study. 48 Labradors fed 25% less typically lived 1.8 years longer, 13.0 years against 11.2 (Trial).
- The trial that decides it has not reported. Loyal says STAY enrolled 1,300 dogs at 72 clinics, and it runs at least four years (Announcement).
- None of this transfers to humans. In people, both low and high IGF-1 track with a higher chance of dying (Meta-analysis).
What to Watch Next
Three signals are worth tracking, in order. First, whether the FDA accepts the manufacturing section (Announcement). Second, whether conditional approval is actually granted. Third, and by far the most important, the STAY result (Trial). Nothing like that has been reported yet for a drug aimed at aging itself, in any species.
While we wait, the dull things still work. Keep the dog lean, look after its teeth, walk it every day, and see the vet before something breaks. The Labrador study tested exactly one of those, and eating less bought those dogs almost two extra years (Trial). The same unglamorous list applies to us.
Something new really is happening here, and so far it has happened on paper. The evidence that the pill helps a dog live longer is still being collected. That part is worth following closely.
This article is for educational purposes and is not medical advice. Talk to a qualified clinician before changing your health regimen.
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