Self-limiting subepidermal bullous disease in a neonatal foal

A 1-day-old Appaloosa colt developed vesicles/bullae involving the skin of the lips and prepuce and multiple mucous membranes. Histopathology revealed subepidermal vesicles/bullae that were clear or contained variable numbers of neutrophils and erythrocytes; The separated epidermis appeared viable. The denuded dermal papillae were often disrupted by microabscesses or coate d with fibrinosuppurative debris. Fragmented basement membrane components w ere attached to exposed dermal papillae. Immunoperoxidase staining of secti ons for deposition of IgG, IgM, IgA, and C3 were positive for IgG at the ba sement membrane and intercellular bridges. Complete recovery ensued. The ch aracteristics of the subepidermal bullous lesions and clinical course of le sion resolution in this foal suggested a drug-induced pathogenesis. The onl y known drug exposure of the foal or mare was topical application of 7% iod ine to the umbilicus at the time of foaling. Similar reactions to iodine ad ministration have been reported in humans.