Drug eruption in a cat following the use of multiple medications to treat systemic conditions

Drug eruption, also known as cutaneous adverse drug reaction, is a rare disease that is difficult to diagnose, requiring a combination of history evaluation, physical assessment, and histopathological examination. Clinically, it presents with variable signs, from mild urticaria to epidermal necrosis. Treatment consists of discontinuing the causative or similar medication; lesion management; and, sometimes, implementing systemic immunosuppressive treatments. The prognosis is generally good, except when there is systemic involvement or extensive skin necrosis. This study aims to describe the lesions, diagnosis, and evolution of a young cat presenting with drug eruption following the use of multiple medications for the treatment of systemic conditions. The patient underwent skin biopsy after showing progression of alopecic and localized lesions, which resulted in a suggestive diagnosis of superficial pustular drug eruption. Previous drug treatments were interrupted, but due to the lack of improvement in the lesion pattern, we chose to re-administer chlorambucil at a dose of 2 mg/cat every 48 h for therapeutic purposes. Up to the present time, the patient has been undergoing treatment and lesion management, with healthy-looking scar tissue and almost complete resolution of the skin lesions.