02158naa a2200229 a 450000100080000000500110000800800410001910000150006024500750007526000090015050001020015952014450026165000140170665000140172065000140173465000100174865300270175870000140178570000180179970000210181777300900183820368822017-12-29       2015    bl uuuu     u00u1 u    #d1 aRIVERO, R.  aAccidental and experimental closantel intoxication in Uruguayan sheep.  c2015  aTítulo em português: Intoxicação acidental e experimental por Closantel em ovinos no Uruguai.  aOne hundred forty eight lambs showed clinical signs of intoxication and 14 died. The clinical signs included mydriasis, nystagmus, and negative pupillary reflex, bilateral blind-ness, bump into objects, and lateral movement of the head. No macroscopic lesions were observed. The histological lesions of the retina were cytoplasmic vacuolization in ganglion cells and in cells of the inner and outer nuclear layers with different degrees of atrophy. Vacuolization and axonal degeneration were observed in the optic nerve, with multifocal areas of fibrosis and infiltration by lymphocytes and Gitter cells. To reproduce the intoxica,-tion, four sheep were given two, four and 10 times the therapeutic dose of Closantel (0.1g/kg of BW). Only the animals receiving 10 times the recommended dose showed clinical signs. The histological examination of the lesions in experimental sheep showed similar results to those described in the accidental outbreak, except for the absence of optic nerve fibrosis and inflammation, characterizing an acute phase. Axonal myelin sheaths loss, fibroblasts and collagen fibers were observed in the ultrastructural study of the optic nerve of accidental intoxicated animals. The optic nerve of experimentally intoxicated animals had vacuoles that separated the myelin sheaths of axons. To prevent outbreaks it is suggested to weigh the animals before Closantel administration to avoid errors in dose calculation.  aBlindness  aClosantel  aPoisoning  aSheep  aAntiparasitic overdose1 aMATTO, C.1 aSOARES, M. P.1 aADRIEN, M. de L.  tPesquisa Veterinária Brasileira, Rio de Janeirogv. 35, n. 7, p. 599-604. jul. 2015.