Cataracts and crooked toes in Brahma chickens.

In 1991, 69% of the cockerels and 15% of the pullets in an inbred flock of approximately 200 dark and light Brahma chickens had unilateral or bilateral cataracts and crooked toes. Affected chickens were normal at hatching but developed cataracts with or without crooked toes by 6 months of age. The cataracts were initially focal and polar but progressed to be diffuse throughout the lenticular cortex. The crooked toes involved one or more of the second, third, and fourth digits and were due to a medial deviation of the distal aspect of the first phalanx. The cataracts and crooked toes were considered likely due to a hereditary defect, based on the following: the history of flock inbreeding; the lack of historical, clinical, or pathological evidence of avian encephalomyelitis or Marek's disease; the presence of lesions only in Brahma chickens and not in the approximately 200 other chickens on the farm kept under the same management and environmental conditions; the age at which the lesions occurred; and the nature of the lesions.

Topical ocular anesthetics in ocular irritancy testing: a review.

The routine use of topical anesthetics to alleviate discomfort associated with in vivo ocular irritancy testing has been advocated. This review provides information about the adverse effects of topical ocular anesthetics and answers the questions: are topical anesthetics practical and effective in ocular irritancy protocols, is long-term use contraindicated, will topical anesthetics alter the response of a test substance, and are there significant side-effects which might cause pain and suffering in test animals? There was no evidence to support the use of a specific topical anesthetic. Further, information about using systemic analgesics or combinations with local anesthetics that would effectively alleviate discomfort associated with ocular irritancy testing without affecting test results was not found. Comprehensive studies are needed to identify the most effective combination of drugs that would ameliorate discomfort associated with ocular irritation testing.

Spontaneous corneal dystrophy and generalized basement membrane changes in Fischer-344 rats.

Groups of young, sexually mature Fischer-344 rats (n = 25/sex) obtained from commercial breeders were examined ophthalmologically and histopathologically to determine the prevalence and severity of corneal basement membrane lesions (corneal dystrophy) and basement membrane changes in select nonocular tissues. Results disclosed a high incidence of corneal basement membrane dystrophy in rats of both sexes from all breeders; however, severity levels were significantly increased in rats obtained from one breeder when compared to others. Furthermore, rats that displayed the most advanced corneal lesions also exhibited more severe basement membrane changes in other organs, especially renal tubules and vascular internal laminae. These findings suggest that both ocular and nonocular dystrophic changes may have been linked through common physiologic (or genetic) mechanisms. Animals that displayed basement membrane lesions were not considered to represent compromised biologic test systems.