On February 25, 2026, Merck Animal Health, a division of Merck & Co., Inc. (NYSE: MRK), made headlines with the announcement of the U.S. Food and Drug Administration (FDA) approval of NUMELVI™ (atinvicitinib tablets). This innovative product is the first and only second-generation Janus kinase (JAK) inhibitor specifically designed for the control of pruritus associated with allergic dermatitis in dogs aged six months and older. Expected to hit veterinary clinics and hospitals nationwide in the spring of 2026, NUMELVI is already being hailed as a significant advancement in animal health.

2. Addressing a Common Problem: Allergic Dermatitis in Dogs

According to veterinary professionals, skin conditions are prevalent in canines, accounting for up to 20% of cases seen in general veterinary practice. Allergic dermatitis not only causes physical discomfort for dogs but can also disrupt the emotional bond between pets and their owners. The condition can lead to significant distress, impacting sleep and routine due to the incessant itchiness and skin lesions associated with it.

A Revolutionary Solution

Dr. Christine McKinney, Senior Professional Services Veterinarian at Merck Animal Health, expressed pride in introducing NUMELVI as a breakthrough in veterinary medicine. “NUMELVI aims to rapidly control pruritus associated with allergic dermatitis—a common condition that causes distress for so many pets and pet owners,” she stated.

NUMELVI is designed as a once-daily treatment that significantly reduces itching from the very first dose. Its active ingredient boasts a high selectivity for JAK1, which minimizes interference with other JAKs that have beneficial immune functions. This characteristic contributes to NUMELVI's compelling safety profile and proven efficacy.

3. Key Features of NUMELVI

Convenience for Clinics and Pet Owners: Dogs weighing as little as 4.4 pounds may require only one or half of a tablet daily, simplifying treatment protocols for veterinary clinics. The product comes in easy-to-dispense bottles that can be stored under standard conditions, eliminating the need for specialized packaging.

Safety and Efficacy: The clinical profile of NUMELVI indicates that it has a proven safety record, making it suitable for dogs as young as six months of age. The JAK inhibitor’s formulation is designed to minimize adverse effects while effectively addressing the symptoms of allergic dermatitis.

4. Expanding Veterinary Medicine

Tim Kowalski, Distinguished Scientist in Discovery Research at Merck Animal Health, emphasized the importance of innovation in veterinary products. “NUMELVI is the first of its kind to enter the market in veterinary medicine, providing a unique profile compared to other JAK inhibitors,” he remarked. “Second-generation JAK inhibitors are already considered the standard of care in human health, and NUMELVI brings that same advanced approach to veterinary medicine.”

This advancement not only reflects Merck's commitment to animal health but also showcases its dedication to enhancing the human-animal bond by improving the quality of life for pets suffering from allergic conditions.

5. Conclusion

With the FDA’s approval of NUMELVI, Merck Animal Health is poised to revolutionize the treatment landscape for allergic dermatitis in dogs. The anticipated availability of this groundbreaking therapy in spring 2026 is expected to bring relief to countless pets and peace of mind to their owners. As the veterinary community prepares for the launch, NUMELVI stands as a testament to ongoing innovation and commitment in the field of animal health.

For further information about NUMELVI, veterinarians and pet owners can visit the dedicated website, numelvi.com.

Original press release