KERATOGLOBUS LESIONS IN THE EYES OF REARING BROILER BREEDERS

This report describes the occurrence of keratoglobus lesions in a rear ing flock of broiler breeder grandparent stock (female line), and its ophthalmological and ocular pathomorphological features. Keratoglobus is known as a recessive sex-linked (Z chromosome) trait in some lines of chickens. The first cases were encountered at 5 weeks of age. At th e end of the rearing period a total of 1.5% of the hock was affected. In the flock and affected birds, no signs of any other disease were de tected. Compared to eyes of healthy hock mates, the most prominent sym ptom was ocular protrusion due to bulging and thinning of the cornea, and increase in anterior chamber depth. In addition, there were mononu clear, granulocytic and plasma cell infiltrates in the iris and corpus ciliare, and mild to minimal exudate in the anterior chamber in all c ases examined. Although the corneal epithelium and collagen bundles ap peared normal on electron microscopy, the corneal endothelium showed s ome loss of cells and the keratocytes some degenerative changes. The c ornea had not lost its transparency and did not show any signs of infl ammation, whereas the conjunctiva contained mononuclear infiltrations. Other eye structures did not show any clinical or pathological change s. The pathogenesis of keratoglobus lesions in chickens is unknown, Al though a hereditary origin seems probable, it is not known whether the inflammatory changes found caused the presented pathology or were sec ondary to the extreme corneal bulging.