Crusting and scaling is a more common presentation. The first affected area is usually the face. Footpad crusting, fissures and lameness may be the only clinical sign in some cases. Ulcerative lesions in the oral cavity or on mucocutaneous junction are not seen. In cats frequently affected areas are the nail bed and perinipple regions.
Diagnosis is made by cytology and histopathology.
Smears from intact pustules are optimal. Smears can also be made by removing crusts and impressing a glass slide on the erosive surface of the skin. They are often in clumps or rafts. On routine histopathology subcorneal pustules are noted on the epidermis. Pustules are filled with neutrophils or eosinophils and often contain acantholytic cells.