A randomised, double-blinded trial to assess the effect of oclacitinib and prednisolone on intradermal allergen and prick tests in dogs with atopic dermatitis.

BACKGROUND:Intradermal (IDT) and prick (PT) tests are used to select allergens for allergen-specific immunotherapy in dogs with atopic dermatitis (cAD). However, the use of antipruritic drugs before performing these tests may influence the results. OBJECTIVE:To evaluate the influence of the drugs oclacitinib and prednisolone on the immediate-phase reactions of IDT and PT. ANIMALS:Thirty client-owned dogs with cAD with positive reactions to at least one allergen extract on IDT or PT. MATERIALS AND METHODS:Dogs were randomly assigned to receive oclacitinib 0.4-0.58 mg/kg per os, every 12 h (n = 14), or prednisolone 0.37-0.65 mg/kg p.o., every 12 h (n = 16) for 14 days. IDT and PT were performed on Day (D)0 before treatment and on D14. RESULTS:At D14 there was no significant reduction in the means of the orthogonal diameters of the positive immediate-phase reactions of the IDT (p = 0.064) in the oclacitinib group; however, in the PT, the diameter of the positive reactions reduced significantly (p = 0.048). In both tests, there was no significant reduction in the total number of positive reactions (IDT, p > 0.999; PT, p = 0.735). In the prednisolone group, the means of the orthogonal diameters of positive immediate-phase reactions were significantly reduced in both tests (IDT, p = 0.001; PT, p ≤ 0.001) and there also was a reduction in the total number of positive reactions (IDT, p = 0.022; PT, p = 0.001). CONCLUSIONS AND CLINICAL RELEVANCE:The use of oclacitinib 0.4-0.58 mg/kg twice daily for 14 days does not interfere with IDT results in dogs with cAD. However, oclacitinib may reduce PT reactivity. The use of prednisolone 0.37-0.65 mg/kg twice daily results in a reduction in both IDT and PT results.