The first approved medicine aimed at extending lifespan could be for dogs – not for humans. In January 2026, the US Food and Drug Administration (FDA) accepted the safety data for LOY-002. At the same time, companies are developing gene therapies against typical age-related diseases in dogs.
LOY-002: a tablet for dogs aged ten and over
The San Francisco company Loyal is developing LOY-002, a daily tablet for older dogs aged ten and over weighing at least 14 pounds (around 6.4 kg). It is intended to slow age-related changes in metabolism, in particular the decline in insulin sensitivity that increases the risk of numerous diseases.
- Safety: the FDA’s Center for Veterinary Medicine has accepted the target animal safety section. This is not yet an approval, but it means that the agency considers the product safe under the conditions applied for.
- Efficacy: the FDA had previously confirmed that there is a “reasonable expectation of effectiveness”.
- Next steps: still outstanding are the review of manufacturing and the application for expanded conditional approval, which Loyal is aiming for in 2027.
- Large study: the STAY study includes 1,300 dogs in 70 veterinary practices; more than 400 dogs on LOY-002 have already been evaluated.
Gene therapy for dogs: Rejuvenate Bio
In June 2026, Rejuvenate Bio, a company spun out of Harvard University’s Wyss Institute, raised six million US dollars and entered into a research collaboration with Merck Animal Health. Products in development include:
- RJB-01: an AAV gene therapy for degenerative mitral valve disease, the most common heart disease in older dogs. In pilot data, it showed sustained gene expression and a favourable safety profile.
- RJB-0402: a gene therapy for the liver that releases the metabolic hormone FGF21. In a recent study, the same hormone extended the lives of old mice by around 20 per cent.
Why dogs?
Dogs share our living environment, develop similar age-related diseases and have much shorter lives – so studies deliver results more quickly. In addition, approval of veterinary medicines is regulated differently. The experience could be valuable for human medicine: a drug that demonstrably brings healthy years of life to dogs would be a strong argument for taking “ageing” more seriously as a target of clinical trials.
Note: This article is for general information only. LOY-002 is not yet approved; please discuss any questions about your dog’s health with your veterinary practice.
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