A Retrospective Case Series Reporting the Clinical Efficacy and Adverse Events of Oclacitinib Administration for Skin Disease in 238 Cats

BACKGROUND: Off-label oclacitinib use for feline dermatoses management is increasing despite the paucity of data regarding optimal dose and adverse events (AEs). OBJECTIVE: Review AEs, clinical efficacy, and dose regimens in cats prescribed oclacitinib. MATERIALS AND METHODS: Retrospective case series of 238 privately owned cats prescribed oclacitinib for dermatological disease. Signalment, history, laboratory abnormalities, oclacitinib dosage (mg/kg/day), treatment duration and AEs using a modified Naranjo Adverse Drug Reaction Probability Scale were retrieved from medical records spanning August 2014 to May 2024. Clinical efficacy was estimated using a pruritus Visual Analogue Scale and medical record lesional descriptions; categorised as complete, partial or no response. RESULTS: The mean (x̄) initial dosage prescribed was 1.89 mg/kg/day. Monotherapy controlled clinical signs in 140 of 238 cats (59%), including 83 of 140 cats (59%) on twice daily (x̄ = 1.85 mg/kg/day) and 57 of 140 cats (41%) on once daily administration (x̄ = 1.05 mg/kg/day). The median treatment duration was 271.5 days (range 1 day-7.5 years). Main diagnoses successfully managed included feline atopic skin syndrome (61%) and pemphigus foliaceus (29%). Thirty-three 'definite' or 'probable' AEs were observed in 32 of 238 cats including: neutropaenia 6.3% (n = 15), gastrointestinal 4% (n = 9), lethargy 1.7% (n = 4), infection 0.8% (n = 2), hyperactivity 0.4% (n = 1), elevated alanine transaminase 0.4% (n = 1) and elevated creatinine 0.4% (n = 1). CONCLUSIONS AND CLINICAL RELEVANCE: Off-label oclacitinib administration in cats appeared to be well-tolerated and effective with AEs typically mild, responsive to dose reduction, and similar to those reported in dogs.