Dystrophic epidermolysis bullosa in Assaf lambs.

Dystrophic epidermolysis bullosa (DEB) was diagnosed in five newborn Assaf lambs from a flock in which around 1-2% of the lambs were lame. Affected animals had marked erythema of the coronary band and subsequent detachment of the hooves. Blisters were present on the lips and in the oral and oesophageal mucosae. Erosions and crusts were noted in the axillary and inguinal areas. Microscopically, there was detachment of the epidermis from the dermis. The roof of these bullous spaces was formed by the intact epidermis with its basement membrane. The bullae were generally filled with pale eosinophilic proteinaceous fluid and erythrocytes. Immunohistochemical analysis revealed absence of collagen VII in the basement membrane zone. The disease in these lambs appears similar to the severe recessive form of human DEB.