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Veterinary dermatology2026; doi: 10.1111/vde.70091

Oclacitinib for Controlling Pruritus and Associated Skin Lesions in 16 Horses With Allergic Dermatitis.

Abstract: Oclacitinib is a Janus kinase inhibitor approved for the treatment of pruritus associated with allergic dermatitis in dogs and may be effective in horses. Objective: To evaluate the efficacy of oclacitinib in reducing pruritus and skin lesions in horses with allergic dermatitis. Methods: Sixteen horses aged ≥ 18 months. Methods: Horses received oclacitinib at 0.25 mg/kg orally once daily for 21 days. Changes in haematological and biochemical parameters were measured on Day (D)0 and D21. The owners were instructed to evaluate the horses using the pruritus Visual Analog Scale (PVAS) on D0, D4, D7, D10, D14, D17 and D21. A veterinary surgeon evaluated skin lesions using a veterinarian lesion score (VLS) and veterinarian alopecia score (VAS) on D0, D7, D14 and D21. Results: From baseline to D21, the median (range) PVAS changed from 5 (4-8) to 2.5 (2-4.5), VLS from 19 (2-42) to 10 (1-38) and VAS from 2 (2, 3) to 2 (1, 2). Of all 16 horses, improvements in PVAS, VLS and VAS were observed in 15, 12 and 8 horses, respectively. Blood profiles revealed significantly increased aspartate aminotransferase, gamma-glutamyl transferase and creatinine levels. White blood cell count, lymphocyte count and blood urea nitrogen significantly decreased. Creatine kinase levels showed individual variability. Conclusions: Oclacitinib effectively reduced pruritus and improved skin lesions in horses with allergic dermatitis. However, caution is advised when administering the drug to horses with renal, hepatic or muscular disorders.
© 2026 The Author(s). Veterinary Dermatology published by John Wiley & Sons Ltd on behalf of ESVD and ACVD.
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Publication Date: 2026-05-31 PubMed ID: 42219233DOI: 10.1111/vde.70091Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study evaluated the effectiveness of oclacitinib, a drug that inhibits Janus kinase enzymes, in reducing itching (pruritus) and skin lesions in horses suffering from allergic dermatitis.
  • Researchers administered the drug for 21 days and monitored clinical signs and blood parameters to assess treatment outcome and safety.

Background and Objective

  • Oclacitinib is an established medication for controlling itching caused by allergic dermatitis in dogs.
  • Its potential effectiveness and safety in horses with similar allergic skin conditions was unknown and needed evaluation.
  • The study’s goal was to assess how well oclacitinib reduces pruritus and improves associated skin lesions in horses with allergic dermatitis.

Study Design and Methods

  • Participants: 16 horses aged 18 months or older diagnosed with allergic dermatitis.
  • Treatment: Each horse received oral oclacitinib at 0.25 mg per kg of body weight once daily for 21 consecutive days.
  • Assessments:
    • Owner evaluations using the pruritus Visual Analog Scale (PVAS) on days 0, 4, 7, 10, 14, 17, and 21 to monitor itching severity.
    • Veterinary assessments of skin lesions using Veterinarian Lesion Score (VLS) and Veterinarian Alopecia Score (VAS) on days 0, 7, 14, and 21.
    • Laboratory testing of hematological and biochemical blood parameters on day 0 and day 21 to identify any physiological changes or adverse effects.

Results

  • Clinical Outcomes:
    • Median pruritus scores (PVAS) decreased from 5 (range 4-8) to 2.5 (range 2-4.5) over 21 days, indicating substantial itch relief.
    • Median lesion scores (VLS) reduced from 19 (range 2-42) to 10 (range 1-38), demonstrating improvement in skin lesions.
    • Alopecia scores (VAS) decreased slightly from median 2 (range 2-3) to 2 (range 1-2), suggesting some improvement in hair loss.
    • Out of 16 horses, improvements were recorded in:
      • 15 horses for pruritus (PVAS)
      • 12 horses for skin lesions (VLS)
      • 8 horses for alopecia (VAS)
  • Laboratory Findings:
    • Significant increases were observed in aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), and creatinine levels, which can be markers of liver or kidney function alteration.
    • White blood cell counts, lymphocyte counts, and blood urea nitrogen levels decreased significantly, indicating possible effects on immune cells and kidney function.
    • Creatine kinase levels varied greatly among individual horses, suggesting variable muscle involvement or reaction to the drug.

Conclusions and Clinical Implications

  • Oclacitinib effectively reduced itching and improved skin lesions in horses with allergic dermatitis over a three-week treatment period.
  • Although beneficial clinically, the laboratory parameter changes indicate that the drug can influence liver, kidney, and muscle function.
  • Caution is recommended when using oclacitinib in horses that already have liver, kidney, or muscular disorders due to potential exacerbation of these conditions.
  • Further studies may be needed to fully understand long-term safety and optimal dosing in equine patients.

Cite This Article

APA
Nuchprayoon N, Maneephan P, Tovanakasame N, Kampang C, Jandee P, Sangsuriya P, Tunhikorn M. (2026). Oclacitinib for Controlling Pruritus and Associated Skin Lesions in 16 Horses With Allergic Dermatitis. Vet Dermatol. https://doi.org/10.1111/vde.70091

Publication

Veterinary dermatology
ISSN: 1365-3164
NlmUniqueID: 9426187
Country: England
Language: English

Researcher Affiliations

Nuchprayoon, Nuttawut
  • Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, Thailand.
Maneephan, Photchanun
  • Mahidol Equine Clinic, Prasuarthorn Animal Hospital, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, Thailand.
Tovanakasame, Natcha
  • VS Sport Club & Siam Polo Park, Samut Prakan, Thailand.
Kampang, Chalidaporn
  • Vet Care Animal Hospital, Bangkok, Thailand.
Jandee, Pusprapa
  • Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, Thailand.
Sangsuriya, Panpanga
  • Department of Pre-Clinic and Applied Animal Science, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, Thailand.
Tunhikorn, Maturawan
  • Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, Thailand.

Grant Funding

  • Faculty of Veterinary Science, Mahidol University
  • Zoetis (Thailand) Company Limited

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