Congenital ocular defects in food-producing animals.

Congenital ocular defects in neonates pose a diagnostic challenge to veterinarians. Defects are usually obvious at birth, but detection depends on the nature and extent of the defect. In addition to congenital ocular defects, other abnormalities may be manifest including multiple system involvement with embryonic mortality, fetal death, mummification, abortion, dysmaturity, premature birth, full-term stillbirth, or nonviable or viable neonate. Many defective neonates are not reported or escape monitoring systems. Although congenital ocular defects are rare, they are important and should be diagnosed. All congenital defects should be regarded as genetic until proven otherwise. Many ocular defects are inherited as simple autosomal recessive traits. Polygenic inheritance appears to be of increasing importance.