- First second-generation JAK inhibitor: NUMELVI (atinvicitinib tablets) is the only FDA-approved second-generation JAK inhibitor for control of pruritus associated with allergic dermatitis in dogs.
- JAK1-selective, once-daily therapy: Demonstrated at least 10-fold selectivity for JAK1 over JAK2, JAK3 and TYK2 in vitro, targeting itch and inflammation pathways.
- Approved for young dogs: Indicated for dogs six months of age and older weighing at least 4.4 pounds.
- Spring 2026 availability: Expected to launch in U.S. veterinary clinics and hospitals nationwide in spring 2026.
The U.S. Food and Drug Administration has approved NUMELVI™ (atinvicitinib tablets) from Merck Animal Health for the control of pruritus associated with allergic dermatitis in dogs six months of age and older.
NUMELVI is the first and only second-generation Janus kinase (JAK) inhibitor approved in veterinary medicine for this indication. Allergic dermatitis is among the most common conditions seen in canine practice, accounting for up to 20% of cases in general veterinary settings, and can significantly affect quality of life for both dogs and their owners.
According to Merck Animal Health, NUMELVI is a once-daily, first-line oral therapy designed to reduce itch beginning with the first dose. In laboratory assays, atinvicitinib demonstrated at least 10 times greater selectivity for JAK1 compared to JAK2, JAK3 and TYK2. By selectively inhibiting JAK1-dependent cytokines involved in itch and inflammation, the therapy aims to control clinical signs while minimizing interference with other immune pathways.
The product is approved for dogs as young as six months of age and weighing at least 4.4 pounds. Merck also highlighted practical considerations for clinics, including no required vaccination schedule adjustments, standard storage conditions, and extended shelf life without specialized packaging.
Second-generation JAK inhibitors are widely used in human medicine, and Merck positions NUMELVI as bringing a similarly advanced approach to veterinary dermatology. The company expects the product to be available nationwide in spring 2026.
Safety Information: NUMELVI is not for use in dogs under six months of age or those with serious infections. As a JAK inhibitor, it may increase susceptibility to opportunistic infections, and new benign and malignant neoplastic conditions have been reported with other products in this class. Safety beyond 28 days has not been evaluated in field studies, nor in breeding, pregnant, or lactating dogs, or in combination with certain systemic immunosuppressive agents. Veterinarians should consult the full product label for complete safety information.
Information sourced from the company’s press release.
