Nature and cause of bilateral ocular dermoids in Hereford cattle.

Nature and cause of bilateral ocular dermoids were investigated by field studies, pedigree analysis, clinical examination, light microscopy, scanning electron microscopy, and transmission electron microscopy. It was determined that ocular dermoids in Hereford cattle are a genetically transmitted defect; characteristics of autosomal recessive and polygenic inheritance were observed. Calves typically were affected bilaterally with multiple, connected ocular growths that clinically, histologically, and ultrastructurally mimicked normal haired skin. Sites most commonly involved included ventro-lateral limbus, third eyelid, medial canthus, eyelid and conjunctiva. Centro-corneal and anterior segmental dermoids also were observed.