Drug reactions can mimic many skin disorders and can result from any drug. EM is characterized by a distinctive target lesion with central clearing. Lesions include erythematous macules or papules that spread peripherally and clear centrally producing arciform lesions. Plaques, vesicles and bulla can also be seen. Bullous and ulcerative lesions of the oral cavity, pinnae, axillae and groin may be present.
Affected animals are systemically ill, febrile and anorectic.
Erythema multiforme may have a variable course. Some cases will regress while others will continue. Animals with extensive lesions may die. The clinical signs of TEN are acute. In humans fever and arthralgia are common prodromal signs.