Loyal, a daily prescription pill targeting senior dogs, could add years to their lives. Is it also a proving ground for human longevity drugs? By Jonathan Small | edited by Brittany Robins | May 04, 2026 One of the hardest parts of loving a dog is knowing you’ll almost certainly outlive them. But a San Francisco startup is on its way to bringing the first dog longevity drug to market. Loyal, founded by 31-year-old Celine Halioua, has developed LOY-002, a daily pill for senior dogs that targets the metabolic drivers of aging. The company has raised over $150 million and completed the largest clinical trial in veterinary medicine history — 1,300 dogs across 70 clinics — to prove the drug works. The FDA has already signed off on its safety and reasonable expectation of effectiveness, putting Loyal on track to launch as soon as next year for around $100 a month. But Halioua’s ambitions extend beyond dog years. She also has her sights on humans.…