Presumed Photoreceptor Dysplasias In Peregrine Falcons (Falco peregrinus) and Peregrine Falcon Hybrids

Abstract We describe a case series of photoreceptor dysplasia with secondary retinal degeneration in juvenile peregrine falcons. Six Peregrine Falcons (Falco peregrinus) and three Peregrine Falcon × Prairie Falcon (Falco mexicanus) hybrids had early-life visual deficits. Eight birds had visual defects shortly after hatching, and one bird had visual deficits first noticed at 5 mo of age. Complete ophthalmic examinations were performed in each animal. Eight of the animals had electroretinograms, and nine of the animals had their eyes examined histologically after euthanasia. Ophthalmic examinations did not reveal consistent and potentially blinding abnormalities, including an absence of ophthalmoscopic retinal lesions. Electroretinographic findings included subnormal amplitudes (with rod responses more abnormal than cone responses), with a negative b-wave amplitude occurring in one bird. Histologically, a reduction in the number of photoreceptors was present with numerous degenerative changes to the remaini...