Overview of equine papular and nodular dermatoses.

Papules and nodules are common lesions on horses and have a variety of underlying causes. This article addresses inflammatory and congenital nodules primarily, including urticaria, erythema multiforme, those nodules caused by infectious agents, epidermoid and dermoid cysts, and the uniquely equine skin tumor, the sarcoid. The eosinophilic nodules and other tumors are covered elsewhere in this issue. Diagnostic and therapeutic approaches to each of the diseases are emphasized.