Accidental closantel poisoning in sheep in the State of Rio Grande do Sul - Brazil
Pohl, Camila BlancoLorenzett, Marina PaulaCecco, Bianca Santana deHenker, Luan CleberPanziera, WeldenDriemeier, David
Background: Verminosis is one of the major health problems in sheep flocks, and is one of the main causes of death insheep worldwide. Closantel is an antiparasitic drug commonly used in sheep; however, its safety margin is narrow, andthis drug may induce intoxication in animals submitted to high doses. Lesions occur mainly in the eyes, and are characterized by edema and compression of the optic nerve, retinopathy, and severe degeneration of ganglia cells. Clinical signsare pupil dilation, which often lead to permanent blindness. This work aims to report an outbreak of sheep mortality dueto closantel intoxication, associated with inadequate anthelmintic administration practices.Case: An on-site visit was conducted to a sheep farm, located in the municipality of Osório, Rio Grande do Sul (RS)- Brazil, in which high mortality was reported. The flock consisted of approximately 300 Texel sheep, managed in anextensive grazing system. Lambs and adult animals were affected. According to the information provided by the farmowner, many animals presented clinical signs of haemonchosis, and a closantel dose of 20 mg / lamb was administeredin all sheep, regardless of body weight. Lambs weighted on average 13 kg. After closantel administration, several sheeppresented neurologic signs and died. At the clinical examination, sheep presented pallor of ocular mucous membranes,as well as submandibular edema. Also, 20 lambs showed signs of blindness, disorientation and bumping into objects, aswell as hypothermia and lack of response to the menace reflex. Three 30 to 45-day-old male lambs that died spontaneously were submitted for necropsy. Grossly, only mild ascites was noted. Histopathological examination of the retinashowed degeneration and fragmentation of photoreceptor layer as well as depletion of the inner nuclear layer, associatedwith pyknosis and karyorrhexis. There was also a reduction in the number of ganglia cells in the ganglion cell layer andatrophy...(AU)
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