ABSTRACTThe replacement of the normal endothelial cell morphology with formation of a fibrocellular posterior collagenous layer by the corneal endothelium was demonstrated in an eight‐year‐old male German shepherd dog with bilateral progressive corneal oedema. Descemet's membrane was multilaminar and thickened. The ultrastructural findings in this dog are similar but not identical to histological changes present in several human corneal disea