FDA clears NUMELVI for allergic itch control in dogs

The FDA has approved NUMELVI (atinvicitinib tablets), a once-daily oral JAK inhibitor from Merck Animal Health for the control of pruritus associated with allergic dermatitis in dogs 6 months of age and older. The approval was granted on February 25, 2026, and positions NUMELVI as the first FDA-approved second-generation JAK inhibitor in veterinary medicine for this indication. According to the FDA’s Freedom of Information summary, the labeled dose is 0.8 to 1.2 mg/kg once daily with food, and the pivotal field study enrolled 289 client-owned dogs with allergic dermatitis. (animaldrugsatfda.fda.gov)

Why it matters: For veterinary professionals, this adds a new oral antipruritic option in a category already familiar to small animal practice, but with a more JAK1-selective profile than older agents, which Merck is emphasizing as a differentiator. FDA documents show the product was studied for short-term itch control over 28 days, and the label includes adverse reactions such as vomiting or nausea, otitis externa, hematuria, anorexia, bacterial skin infection, diarrhea, crystalluria, lethargy, and urinary tract infection. The drug is not for use in dogs younger than 6 months or dogs with serious infections. (merck-animal-health-usa.com)

What to watch: Merck has said NUMELVI is expected to reach U.S. veterinary clinics in spring 2026, so the next question is how quickly practices adopt it relative to existing itch-management protocols. (dvm360.com)