This study retrospectively investigated the treatment outcomes of oclacitinib in 85 dogs with atopic dermatitis in Japan. Atopic dogs treated with systemic oclacitinib (0.4–0.6 mg/kg, twice a day for up to 14 days, then once a day thereafter) were the subjects of this study. The cases were divided into two groups: Group A (dogs were well controlled with oclacitinib at 0.4–0.6 mg/kg, once a day or every other day for more than 6 months after 14 days of treatment with oclacitinib, n=43); and Group B (dogs were difficult to manage with oclacitinib at 0.4–0.6 mg/kg once a day, n=42). Statistical analysis was performed using logistic regression analysis. There were no significant differences in breed, sex, age, or Favrot’s diagnostic criteria for canine atopic dermatitis between groups A and B (p>0.05). In univariate analysis, the odds ratio of Group A was significantly lower than that of Group B in moderate or more severe skin eruption, lesional distribution on the axilla or lumbar back, and seborrhea (p<0.05). In multivariate analysis, the odds ratio of Group A was significantly lower than that of Group B in lesional distribution on the axilla or lumbar back (Odds ratios: axilla 0.388, lumbar back 0.298, p<0.05). The results of this study suggest that the distribution of skin lesions, the severity of the skin eruption, the skin condition and the presence or absence of localized lesions may influence the treatment outcome of oclacitinib in dogs with atopic dermatitis.

An eight-year-old neutered female Chihuahua, diagnosed with atopic dermatitis and undergoing long-term treatment with prednisolone, presented multiple black papules primarily on her left hind limb. Despite discontinuing prednisolone and transitioning to oclacitinib, no improvement in the lesions was observed. Cutaneous papillomatosis was diagnosed by histopathological examination. Although there was no improvement in the lesions after 14 days of combination therapy with azithromycin, a reduction in their severity was observed after one month, and after five months, the severity of the lesions had significantly reduced. This case suggests that azithromycin could be a potential therapeutic option for unmanageable cutaneous papillomatosis, but it appears that at least one month of administration is necessary.