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Numelvi™
(atinvicitinib tablets)


Discover the first and only second-generation Janus kinase (JAK) inhibitor for dogs that is highly selective for JAK1,1* the primary driver of itch and inflammation.2

* Over the other JAK enzymes in in vitro assays.

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Overview

Technical

Numelvi™ (atinvicitinib tablets) is a highly selective, effective, safe, and simple treatment for the control of pruritus associated with allergic dermatitis in dogs and puppies 6 months of age and older.

Features & Benefits

At least 10X more selective for JAK11*

High selectivity for JAK1 minimizes interference with the beneficial immune functions of the other JAKs2

Rapid itch relief

Starts reducing itch within 2-4 hours3†

Significant reduction in itch

>82% of dogs showed significant‡ improvement within 1 week4

Broad age and weight range

Safe for dogs and puppies as young as 6 months of age and can be used in dogs weighing at least 2 kg

Simple for you and pet owners

Easy once-daily dosing from day 1§

* Over the other JAK enzymes in in vitro assays.
† In a canine interleukin-31 (cIL-31)-induced pruritus model.
‡ A ≥2 cm reduction in owner Pruritus Visual Analog Scale.
§ Numelvi is taken at or around mealtime.

How It Works

Explore the revolutionary science behind Numelvi. Watch how this second-generation JAK inhibitor offers you and your allergic dermatitis patients a selective, effective, safe, and simple treatment that works fast by targeting JAK1, the primary driver of allergic itch and inflammation.2

Numelvi Specifications

Indication

For the control of pruritus associated with allergic dermatitis in dogs 6 months of age and older

Dosage and Administration

The average recommended dose is 1.0 mg/kg (0.8 to 1.2 mg/kg) orally once daily with food (at or around mealtime)

Safety

Safe for dogs and puppies as young as 6 months of age and can be used in dogs weighing at least 2 kg

Supplied

  • Uncoated and unflavored compressed tablets
  • 4 tablet strengths: 4.8 mg, 7.2 mg, 21.6 mg, 31.6 mg
  • 30- and 90-count bottles

Most Dogs Require Just a Single Tablet or Half-Tablet Daily

Numelvi is administered orally, once daily, at or around mealtime at a dose of 0.8-1.2 mg/kg (0.26-0.54 mg/lb) body weight according to the dosing table below.||

|| For dogs ≥174.3 lb (≥79.1 kg), administer the appropriate combination of tablet strengths to achieve the target dose of 0.8-1.2 mg/kg.

0.38 × 0.19 inches

0.43 × 0.21 inches

0.62 × 0.31 inches

0.71 × 0.36 inches

Tablets not to scale.

Dosing Calculator

Determine the right dose instantly. Simply enter your patient’s weight to calculate.

LAUNCH CALCULATOR

Get Numelvi for Your Clinic

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Significant Reduction in Itch From the First Dose5

* Numelvi is significantly different from placebo.
† In a canine interleukin-31 (cIL-31)-induced pruritus model.
Owner Pruritus Visual Analog Scale (PVAS).

Significant Itch Reduction in >82% of Dogs Within 1 Week4

* Numelvi is significantly different from placebo.
All dogs enrolled had a PVAS score of 6 or higher (moderate or severe) at beginning of the study.
A ≥2 cm reduction in owner PVAS is considered as a clinically relevant threshold, but is dependent on the baseline owner PVAS score.6

Proven Safety and Efficacy in Clinical Studies

Vaccine Response Study: Ability of Healthy, 6-Month-Old Unvaccinated Dogs to Respond to Vaccination7


# Multivalent modified live canine distemper virus (CDV), modified live canine adenovirus type-2 (CAV2), and modified live canine parvovirus (CPV) vaccine.

Vaccine Response Study Results: Adequate Serological Response to Vaccination7

No Serious Treatment-Related Adverse Reactions Reported

No veterinary intervention or symptomatic treatment required.8
In clinical trials, the most observed adverse events were vomiting and nausea.

Disease Information

Allergic Dermatitis in Dogs9

Allergic dermatitis is an abnormal reaction of the immune system to certain substances that is associated with itch and skin inflammation9

Primary Causes

Four Types of Allergic Dermatitis10

Atopic Dermatitis

Caused by absorption of environmental allergens, such as pollens, house dust mites, molds, and danders

Cutaneous Adverse Food Reaction11

Caused by ingestion of dietary proteins, such as chicken, beef, dairy, and wheat

Flea Allergy Dermatitis

Caused by proteins and other substances in flea saliva

Other

  • Insect bite
  • Contact

Clinical Signs

Itch-Related Behaviors

  • Scratching
  • Rubbing
  • Chewing
  • Licking
  • Excessive grooming
  • Rolling
  • Scooting
  • Head-shaking

Commonly Affected Areas

  • Feet
  • Face
  • Ears
  • Front legs (flexural surfaces)
  • Axillae
  • Abdomen

Increased Risk of Secondary Skin Infections and Decline in Well-Being

Bacterial Infection

(Staphylococcal pyoderma)

Yeast Infection

(Malassezia dermatitis)

Ear Infection12

(Otitis externa)

  • Seen in up to 50% of dogs with atopic dermatitis
  • Can be recurrent

Decline in Quality of Life13

  • Disruption to sleep, appetite, play, performance, activity, behavior

Skin Conditions Are Extremely Common in Dogs

  • Allergic dermatitis is a lifelong, recurrent condition
  • Skin allergies and ear infections accounted for more than 20% of insurance claims in 202314
  • Atopic dermatitis affects 3-15% of dogs worldwide15
  • Certain dog breeds have a genetic predisposition to atopic dermatitis16

IMPORTANT SAFETY INFORMATION

NUMELVI is not for use in dogs less than 6 months of age or those with serious infections. NUMELVI may increase susceptibility to opportunistic infections, including demodicosis and interdigital furunculosis. Consider the risks and benefits of treatment prior to initiating NUMELVI in dogs with a history of recurrent demodicosis. NUMELVI is a JAK inhibitor. New neoplastic conditions (benign and malignant) have been reported in dogs treated with other JAK inhibitors. The effectiveness and safety of NUMELVI have not been evaluated in a field study beyond 28 days. The safe use of NUMELVI has not been evaluated in breeding, pregnant, or lactating dogs, nor in combination with glucocorticoids, cyclosporine, or other systemic immunosuppressive agents. For complete safety information, refer to the product label.

References

  1. Kowalski T, Schuette S. The second-generation Janus kinase inhibitor atinvicitinib is a potent and highly selective inhibitor of JAK1. Vet Dermatol. 2026;0:17. https://doi.org/10.1111/vde.70046
  2. Huang IH, Chung WH, Wu PC, Chen CB. JAK-STAT signaling pathway in the pathogenesis of atopic dermatitis: an updated review. Front Immunol. 2022;13:1068260. doi:10.3389/fimmu.2022.1068260
  3. Kowalski T, Prohaczik A, Locke K, et al. The second-generation Janus kinase inhibitor atinvicitinib significantly reduces pruritus 2-4 hours after dosing dogs in a canine interleukin-31 model. Vet Dermatol. 2026;0:17-18. https://doi.org/10.1111/vde.70046
  4. Data on File. Study Summary REF-12964. Merck Animal Health. 
  5. Numelvi. Product label. Merck Animal Health; 2025.
  6. Cosgrove SB, Wren JA, Cleaver DM, et al. Efficacy and safety of oclacitinib for the control of pruritus and associated skin lesions in dogs with canine allergic dermatitis Vet Dermatol. 2013;24(5):479-e114. doi:10.1111/vde.12047 
  7. Freedom of Information Summary. NADA 141-596. 
  8. Data on File. Study Summary REF-11202. Merck Animal Health. 
  9. Mueller R. Atopic dermatitis and food-responsive dermatosis. In: Jackson HA, Marsella R, eds. BSAVA Manual of Canine and Feline Dermatology. 4th ed. BSAVA; 2021:76-81. 
  10. Hensel P, Santoro D, Favrot C, Hill P, Griffin C. Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification. BMC Vet Res. 2015;11:196. doi:10.1186/s12917-015-0515-5
  11. Jackson HA. Food allergy in dogs and cats; current perspectives on etiology, diagnosis, and management. J Am Vet Med Assoc. 2023;261(S1):S23-S29. doi:10.2460/javma.22.12.0548
  12. Miller J, Simpson A, Bloom P, et al. 2023 AAHA management of allergic skin diseases in dogs and cats guidelines. J Am Anim Hosp Assoc. 2023;59(6):255-284. doi:10.5326/JAAHA-MS-7396
  13. Noli C. Assessing quality of life for pets with dermatologic disease and their owners. Vet Clin North Am Small Anim Pract. 2019;49(1):83-93. doi:10.1016/j.cvsm.2018.08.008 
  14. Skin allergies, gastrointestinal disease among most common conditions that prompt veterinary visits. Nationwide. April 24, 2024. Accessed October 24, 2024. https://news.nationwide.com/most-common-conditions-that-prompt-veterinary-visits-2024/
  15. Hillier A, Griffin CE. The ACVD task force on canine atopic dermatitis (I): incidence and prevalence. Vet Immunol Immunopathol. 2001;81(3-4):147-151. doi:10.1016/s0165-2427(01)00296-3
  16. Hensel P, Saridomichelakis M, Eisenschenk M, et al. Update on the role of genetic factors, environmental factors and allergens in canine atopic dermatitis. Vet Dermatol. 2024;35(1):15-24. doi:10.1111/vde.13210