Retinal dysplasia in wild otters (Lutra lutra).

Eyes from 88 otters found dead in south-west England between 1990 and 2000, were collected as part of a larger pathological study. Histopathological examination of 131 eyes revealed dysplastic changes such as rosetting and folding in the retinas of 26 of the otters. In the eyes of 42 of the otters there were postmortem and fixation-induced retinal detachment which complicated the differentiation of dysplastic from normal retina, but 11 eyes had folds which probably indicated a dysplastic pathology. The eyes of 18 of the otters had inflammatory or autolytic changes which precluded a definitive evaluation of their dysplastic status. Liver samples from 55 of the otters were analysed for a range of polychlorinated hydrocarbons and for vitamin A. The otters with dysplastic retinas had significantly lower concentrations of vitamin A and higher concentrations of dieldrin than the otters with normal retinas.