Merck Animal Health has announced that the US FDA has approved NUMELVI (atinvicitinib tablets), the first and only second-generation Janus kinase (JAK) inhibitor for controlling pruritus associated with allergic dermatitis in dogs six months and older. 

 

The medication is set to hit veterinary clinics nationwide in spring 2026.

 

“Merck Animal Health is proud to introduce NUMELVI, our latest advancement geared at rapidly controlling pruritus associated with allergic dermatitis, a common condition that causes distress for so many pets and pet owners,” said Christine McKinney, Senior Professional Services Veterinarian, Merck Animal Health.

 

McKinney emphasized the impact for both dogs and their owners: “With more than 70 years of innovation and commitment to animal health, we are confident that NUMELVI will offer veterinary professionals a groundbreaking, first-of-its-kind solution aimed at improving the health and well-being of dogs as young as six months of age to mature dogs – and ultimately providing peace of mind for the people who care for them. 

 

"NUMELVI also offers added convenience for veterinary clinics; most dogs, starting at weights as low as 4.4 pounds, require only one or half of a tablet, and there is no need to adjust vaccination schedules. Plus, NUMELVI comes in easy to dispense bottles and can be stored under standard conditions. Its active ingredient is intrinsically stable providing the longest shelf life among JAK inhibitor tablets in veterinary medicine.”

 

Skin conditions affect up to 20% of dogs seen in general veterinary practice, causing physical discomfort, emotional distress, and sleep disruption for both pets and owners. NUMELVI, a once-daily treatment, reduces itch from the first dose. It is at least 10 times more selective for JAK1 than JAK2, JAK3, and TYK2, inhibiting the JAK1-dependent cytokines that drive allergic dermatitis while minimizing impact on beneficial immune functions.

 

“Merck Animal Health is continuously working to expand its portfolio to include innovative veterinary medicinal products that meet the needs of dogs and their owners,” said Tim Kowalski, Distinguished Scientist, Discovery Research, Merck Animal Health. 

 

“NUMELVI, a second-generation JAK inhibitor, is the first of its kind to enter the market in veterinary medicine, giving it a unique profile compared with other JAK inhibitors. Second-generation JAK inhibitors are already considered the standard of care in human health, and NUMELVI brings that same advanced approach to veterinary medicine.”