Rahway, New Jersey, USA — February 25, 2026
The U.S. Food and Drug Administration (FDA) has approved NUMELVI™ (atinvicitinib tablets) from Merck Animal Health for the control of pruritus associated with allergic dermatitis in dogs, marking the first approval of a second-generation Janus Kinase (JAK) inhibitor in veterinary medicine for this indication. Allergic dermatitis is one of the most common inflammatory skin diseases in companion animals, often causing severe itching, lesions and reduced quality of life. The approval introduces a targeted oral therapeutic designed to deliver rapid itch relief while addressing the underlying inflammatory signaling pathways driving the condition.
Targeted JAK1 Mechanism for Itch Control
NUMELVI works by selectively inhibiting JAK1-dependent cytokine signaling, a central driver of allergic inflammation and pruritus. This targeted mechanism allows the therapy to reduce itch and skin inflammation while minimizing broader immune suppression. As a once-daily oral tablet, it offers convenient administration for dogs aged six months and older, supporting both acute and chronic dermatitis management.
Clinical Value and Safety Profile
Clinical data demonstrate strong antipruritic efficacy with a favorable safety profile driven by functional selectivity for JAK1 over other kinase pathways. By avoiding excessive inhibition of JAK2 and related immune regulators, the therapy maintains effectiveness while reducing off-target risks. Veterinary guidance remains essential, particularly regarding infection monitoring, as with other immunomodulatory agents.
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Advancing Veterinary Immunology Therapeutics
The approval reflects growing innovation in companion animal pharmaceutical development, bringing human-grade kinase inhibitor science into veterinary dermatology. With increasing demand for targeted treatments that reduce reliance on corticosteroids, NUMELVI expands the therapeutic arsenal available to veterinarians managing chronic allergic skin disease.
Source: Merck press release
