Acute amaurosis in sheep due to rafoxanide neurotoxicity
1991
Odiawo, G.O. (University of Zimbabwe, Harare (Zimbabwe). Faculty of Veterinary Science)
Acute amaurosis due to rafoxanide neurotoxicity is described in a flock of sheep. The clinical signs included blindness and mydriasis. Both the corneal and menace reflexes were absent. Dysponea and recumbency were seen in a few affected animals. The general body condition was poor and they were anaemic. Post mortem examination showed emaciation, anaemia, helminthiasis and fasciolasis. Histological examination of the brain, optic nerves and eyes showed symmetrical status spongiosus of the deep white matter of the cerebral cortex especially the perivascular areas of the hippocampus and septum pellucidum, with a wide variation in the extent of the spongiosis in the corpus collosum in the brains examined. Other areas affected included the cerebellar white matter, the pons and the medulla. Most of the cerebrocortical neuronal laminae contained darkly stained neurons. There was also neuronal chromatolysis with gliosis and oedema of the neurophil and astrocyte proliferation. The optic nerves showed demyelination with Schwann cell proliferation, oedema and congestion. The retinal neurophil was congested and haemorrhagic, but no structural changes were seen, suggesting that retinal changes do not contribute to the blindness in acute cases of rafoxanide poisoning
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