Bright Blindness in Sheep—The Relationship to Environment

Abstract

SUMMARY The 1965 female progeny of three flocks with a high incidence of bright blindness were retained and examined for 4 years. Of 104 lambs which remained in their normal environment, sixteen developed retinal atrophy. Eight of thirty-six brought to this environment from farms where the disease was unknown also developed retinal atrophy. None of the forty-five lambs moved away from the hill grazings were affected, even though they were in contact with cases of retinal atrophy. This condition seems to be associated with an environmental effect—possibly the ingestion of bracken.