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

NUMELVI, a highly-selective, second-generation JAK inhibitor for dogs, delivers at least 10-fold greater selectivity for JAK1 compared with JAK2, JAK3, and tyrosine kinase (TYK)–2, and is suitable for dogs as young as 6 months.

VIENNA, AUSTRIA, September 04, 2025 – MSD Animal Health, a division of Merck & Co., Inc., Rahway, NJ, USA (NYSE: MRK), today announced the launch of NUMELVI®, the first and only second-generation JAK inhibitor approved by the European Commission on July 24, 2025, approved for the treatment of pruritus associated with allergic dermatitis in dogs.

With at least 10 times more selectivity for JAK1 over the other JAK enzymes (JAK2, JAK3, and TYK-2), NUMELVI effectively targets pruritus (itching) associated with allergic dermatitis, including atopic dermatitis and clinical signs of atopic dermatitis, while minimizing disruption of immune defense and blood cell production.1 NUMELVI starts to reduce itch significantly within 2–4 hours of the first dose in dogs as young as 6 months.²

“NUMELVI represents a breakthrough as the first second-generation JAK inhibitor specifically designed for dogs,” said Rob Kelly, Executive Vice President, Global Marketing and EURAM Lead, MSD Animal Health. “This launch reflects our ongoing commitment to delivering innovative solutions that address the unique medical needs of veterinarians and their patients.”

Dr. Regina Wagner, a veterinary dermatology specialist from Austria, explains: “Itch affects up to 20% of dogs in general veterinary practice3,4 and is one of the most common reasons for clinic visits.5 Allergic dermatitis can significantly impact quality of life for both the dog and its owner due to emotional distress, interruptions in sleep and routines, increased expenses, and time lost to provide treatment and veterinary follow-up.6 Until now, first-generation JAK inhibitors target JAK enzymes with little to no selectivity 7. NUMELVI addresses this unmet need with highly selective JAK1 inhibition, while providing fast, effective relief.”

What Sets NUMELVI Apart

Unlike first-generation JAK inhibitors that block more than one JAK enzyme, the JAK1 selective targeting of NUMELVI helps significantly reduce the risk of adverse effects related to inhibition of other JAK family enzymes.” ¹ This selectivity preserves immune function and supports the body’s ability to defend against infections.

“At MSD Animal Health, our commitment is to advance therapeutic solutions that address critical unmet medical needs in veterinary medicine. Pruritus associated with allergic dermatitis represents a prevalent and challenging immunological condition that significantly impairs canine quality of life,” said Rainer Roepke, Associate Vice President, Preclinical Research & Development, MSD Animal Health. “NUMELVI, a next-generation Janus kinase (JAK) inhibitor, delivers a targeted mechanism of action that precisely modulates key inflammatory pathways, offering veterinarians a novel, first-line treatment option. Our development program has demonstrated robust efficacy and a strong safety profile, advancing the standard of care in veterinary dermatology.

Veterinarian-designed, once-daily NUMELVI is registered for dogs as young as 6 months and registered tablet strengths are suitable for dogs from 2 kg.¹ Available in 30- and 90-day packs, the single-scored tablets allow for accurate dosing, making treatment simple and convenient for use at home.

Clinical trials have confirmed that NUMELVI represents an effective and well tolerated treatment for dogs with pruritus associated with allergic dermatitis, including atopic dermatitis and clinical signs of atopic dermatitis with a unique selectivity and safety profile. Common adverse events observed are emesis, diarrhea, lethargy and anorexia¹.

NUMELVI is a prescription-only veterinary medication. It should be used under the care of a veterinarian in accordance with local regulations and the product label. For more information about NUMELVI, visit www.msd-animal-health.com/products/companion-animals.

About MSD Animal Health

At MSD, known as Merck & Co., Inc., Rahway, N.J., USA in the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than a century, we’ve been at the forefront of research, bringing forward medicines, vaccines and innovative health solutions for the world’s most challenging diseases. MSD Animal Health, a division of Merck & Co., Inc., Rahway, N.J., USA, is the global animal health business of MSD. Through its commitment to The Science of Healthier Animals®, MSD Animal Health offers veterinarians, farmers, producers, pet owners and governments one of the widest ranges of veterinary pharmaceuticals, vaccines and health management solutions and services as well as an extensive suite of connected technology that includes identification, traceability and monitoring products. MSD Animal Health is dedicated to preserving and improving the health, well-being and performance of animals and the people who care for them. It invests extensively in dynamic and comprehensive R&D resources and a modern, global supply chain. MSD Animal Health is present in more than 50 countries, while its products are available in some 150 markets. For more information, visit www.msd-animal-health.com and connect with us on LinkedIn and X (formerly Twitter).

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Media Contact

Anne-France Quentric Melay – Anne-france.quentric.melay@msd.com

Tonja Grassmann – Tonja.Grassmann@msd.de

This is the SPC: https://medicines.health.europa.eu/veterinary/en/documents/download/7afee6c1-cf8c-4386-8d28-9a2572242783