MSD Animal Health Launches NUMELVI® (atinvicitinib) Tablets for Dogs – A Veterinary Innovation in Fast, Effective and Safe Targeted Itch Relief

MSD Animal Health, a division of Merck & Co., Inc., Rahway, N.J., USA (NYSE:MRK), today announced that the European Commission (EC) has approved NUMELVI™ (atinvicitinib) Tablets for Dogs.

NUMELVI is a once-daily, first-line treatment, and is the only second-generation Janus kinase (JAK) inhibitor indicated for the treatment of pruritus associated with allergic dermatitis including atopic dermatitis and treatment of clinical manifestations of atopic dermatitis in dogs. With a once-daily treatment regimen, NUMELVI is clinically effective after the first dose.

NUMELVI inhibits the effect of JAK1-dependent cytokines involved in itch and inflammation in allergic dermatitis and atopic dermatitis and is at least 10-fold more selective for JAK1 than for JAK2, JAK3 and TYK2.  JAK1 selectivity minimizes interference with the beneficial immune functions of the other JAKs, resulting in a compelling safety profile with proven efficacy in dogs and puppies. It is the only JAK inhibitor approved for use in dogs as young as six months of age. NUMELVI also allows for an adequate serological response to vaccination and has no known drug interactions.

“Pruritus associated with allergic dermatitis is a common condition that causes distress and discomfort for so many dogs,” said Holger Lehmann, DVM, PhD, vice president and global head, research and development for pharmaceuticals, MSD Animal Health. “With today’s authorization of NUMELVI, MSD Animal Health is proud to offer veterinarians and pet owners an innovative next generation JAK inhibitor that delivers clinical benefits over current standard of care.”

This approval by the European Commission follows the European Medicines Agency’s Committee for Veterinary Medicinal Products (CVMP) positive opinion June 12, 2025.