抄録
A total of 26 cases of congenital blindness were encountered among calves of both sexes of the black Japanes native breed in Awaji Island, Hyogo Prefecture. No Holsteins kept under the same conditions were involved in these cases.
In the blind calves the pupils were dilated exhibiting no response to light. Ophthalmoscopy of several blind calves showed no abnormality in the fundus, but there was no optical sensation. Necropsy and histopathological examination of a 4-day-old blind calf revealed the defect of the sphincter pupillae, malformations of the retina andc opti disc, and arteria hyaloidea persistens.These results strongly suggested that the optic nerve might get atrophied during many days after birth, and that stenosis might be caused in the optic canal as a secondary pathological change.
Thirteen of the blind calves were studied genetically. Two of them exhibited, complicated dwarf and muscle contracture. It was possible to recognize such hereditary malformations derived from an undesirable recessive gene as prologed pregnancy, atresia ani, deformed nipples, leg contracture, different hair color and dicephalus.
Consequently, there was no doubt that the present cases of congenital blindness had been induced by a cause of ereditary origin.
