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Year 2005 - Volume 25, Number 2
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Intoxicação experimental por Tetrapterys multiglandulosa (Malpighiaceae) em ovinos, p.91-96
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Riet-Correa G., Terra F.F., Schild A.L., Riet-Correa F. & Barros S.S. 2005. [Experimental poisoning by Tetrapterys multiglandulosa (Malpighiaceae) in sheep.] Intoxicação experimental por Tetrapterys multiglandulosa (Malpighiaceae) em ovinos. Pesquisa Veterinária Brasileira 25(2):91-96. Curso de Medicina Veterinária, Campus de Castanhal, UFPA, Castanhal, PA 68740-080, Brazil. E-mail: griet@ufpa.br
Cardiac fibrosis was observed in a calf showing dullness, weakening and respiratory insufficiency in a farm in the state of São Paulo, where cardiac insufficiency, abortion and nervous signs in cattle were associated with the ingestion of Tetrapterys multiglandulosa. The objectives of this paper were to determine the susceptibility of sheep to the intoxication by T. multiglandulosa, to describe the clinical and pathological characteristics of the intoxication, and to evaluate the possibility of using sheep as an experimental species for toxicological studies with this plant. In a previous experiment to determine the toxicity of T. multiglandulosa to be used in sheep, the green plant was given to a steer at the dose of 22g per kg body weight (g/kg/bw), daily, during 9 days. After 9 days the steer showed nervous signs, and on the 12thday was euthanatized. No gross lesions were observed at necropsy. Status spongiosus was observed on the deeper layers of the cerebral cortex and subcortical white matter. Six male sheep were divided in three groups of two sheep each. Group 1 (Sheep 1 and 2) received daily doses of 6 g/kg/bw of the dry plant, during 30 days; Group 2 (Sheep 3 and 4) received daily doses of 3 g/kg/bw, during 60 days; and Group 3 was the control group. Sheep 1 was euthanatized 30 days after the start of the ingestion. Only cardiac arrhythmia was observed clinically, and no lesions were observed at necropsy. Sheep 2, 3 and 4 had also cardiac arrhythmia from day 9, 12 and 18, respectively. From day 52 they started to show depression, reluctance to move and incoordination. Clinical signs got gradually worst and the sheep were euthanatized on days 60, 70 and 80, when clinical signs were marked, and the animals will die at any moment. Hydrothorax, hydropericardium, ascites, nutmeg appearance of the liver and hard whitish myocardium, mainly in the interventricular septum and left ventricle, were observed at necropsy. Histologically, the heart of Sheep 2, 3 and 4 had areas of fibrosis associated with mononuclear cell infiltration. No lesions were found in the heart of Sheep 1. The 4 treated sheep had status spongiosus in different areas of the cerebrum and brain stem, mainly of the deep layers of the cerebral cortex and subcortical white matter. Status spongiosus were also observed in the cerebellar white matter and cervical medulla. In the later the vacuolization was moderate in the white matter and mild in the grey matter. Status spongiosus were mild in Sheep 1 and moderate to severe in Sheep 2, 3 and 4. On electron microscopy it was observed that the status spongiosus is due to an intramyelinic edema. No gross or histologic lesions were observed on the two control sheep, which were euthanized on day 80 after the start of the experiment. |
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