We performed a retrospective evaluation of 29 cats with presumed idiosyncratic adverse cutaneous drug reactions (ACDR). ACDR accounted for 2% of the cats examined by the Dermatology Service over a period of 15 years. No breed, age, sex, or retroviral predilections were found. The most common cutaneous reaction patterns were contact dermatitis, contact otitis externa, allergy-like pruritus, and vasculitis. The most commonly incriminated drugs were amoxicillin clavulanate and chlorhexidine scrub. Drug withdrawal resulted in resolution of the skin eruptions within 2 to 6 weeks in 25 cats, and 12 weeks in 4 cats. Two cats with cefovecin-associated necrotizing vasculitis required additional anti-inflammatory therapy.

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A 19-year-old, spayed female, domestic short-haired cat was presented with approximately 1.0 cm erosion of the skin of the chin. Cytologically, the smears were cellular with cohesive groups occasionally forming gland like structures and short chains of a few cells in straight or curved lines. Histologically, the epidermis was focally thickened with a neoplasm which was composed of neoplastic epithelial cells arranged in nests, pseudocysts, pseudoglands with marked acantholysis, and occasional keratin pearls. Anisocytosis and anisokaryosis were severe and mitotic figures were frequently observed. The pathological features described above were consistent with acantholytic squamous cell carcinoma. Squamous cell carcinoma should be included in differential diagnoses for dermatitis-like lesions in the skin of the chin of even old-aged cats.

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Glucocorticoid-induced adrenocortical suppression is a major concern in its systemic administration, rather than topical application, in the dog. We described the cases of two dogs respectively treated with triamcinolone acetonide combined cream for 3 months and hydrocortisone aceponate spray for 10 months. The dogs presented with skin lesions and adrenocortical suppression, which was confirmed by an ACTH stimulation test. Skin and adrenocortical function returned to normal after withdrawal of topical glucocorticoids. These results demonstrate that long-term use of topical glucocorticoids including an antedrug has the potential to affect the pituitary-adrenal system.

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