FDA Approves NUMELVI™ (atinvicitinib tablets) for Dogs
The United States Food and Drug Administration has approved NUMELVI™ (atinvicitinib tablets), a new treatment for itch associated with allergic dermatitis in dogs, developed by Merck Animal Health. The company says the medication is the first and only second-generation Janus kinase (JAK) inhibitor approved in the United States for this indication.
The drug is expected to become available at veterinary clinics and hospitals nationwide in spring 2026.
NUMELVI is indicated for dogs six months of age and older for the control of pruritus associated with allergic skin disease, a condition that is commonly seen in veterinary practice. Dermatologic disease can account for a significant portion of general small animal visits and can negatively impact quality of life due to persistent itching, skin lesions, and associated behavioral stress.
Company scientists say the product works as a once-daily oral treatment that targets JAK1-dependent inflammatory signaling pathways involved in allergic dermatitis. According to Merck Animal Health researchers, the drug is designed to be highly selective for JAK1 compared to other JAK pathway proteins, which may help minimize interference with immune functions while maintaining anti-itch efficacy.
Veterinary dermatologist Christine McKinney said the approval represents an advancement in managing chronic allergic skin disease in dogs. She noted that the medication was developed to provide rapid itch control while offering dosing convenience for veterinary practices and pet owners.
Researchers also highlighted that second-generation JAK inhibitors are already widely used in human medicine, and the development of similar targeted therapies in veterinary medicine represents a growing area of translational research in dermatology and immunology.
The medication is available in tablet form and can be stored under standard conditions. According to company information, most dogs will require either a full or half tablet depending on body weight, with dosing starting at approximately 4.4 pounds.
Allergic dermatitis is one of the most common dermatologic conditions in dogs and can represent up to 20% of general veterinary clinical cases. Untreated chronic itch and inflammation can disrupt sleep, behavior, and the bond between pets and owners.
Merck Animal Health is a global animal health company and a division of Merck & Co., Inc., which has invested heavily in veterinary pharmaceutical research and vaccine development for more than a century.
The company emphasized that NUMELVI will be used as a prescription medication under veterinary supervision. Safety information notes the drug should not be used in very young dogs, dogs with active serious infections, or in breeding or pregnant animals. Like other immune-modulating medications, there is potential for increased susceptibility to opportunistic infections, and veterinarians are encouraged to weigh risks and benefits before prescribing.
Industry researchers said the approval reflects continued expansion of targeted therapies in veterinary medicine, offering new options for managing chronic skin disease while supporting pet quality of life and client satisfaction.
For veterinarians and pet owners, the product’s launch is expected to add another therapeutic option for managing allergic skin disease alongside existing treatments and multimodal dermatologic care strategies.
