Experimental intoxication of sheep and cattle with Wedelia glauca.

Wedelia glauca was administered experimentally to 11 sheep and 4 cattle. The minimum toxic dose for both species was of 4 to 5 g of fresh plant/kg bw. Clinical signs were depression, muscle fasciculations, increased respiratory and cardiac frequencies, opisthotonous, sternal or lateral recumbency and terminal paddling movements. Time of onset of signs ranged from 12 to 40 h after dosing. Serum AST, LDH and GGT were increased. Three cattle and 5 sheep died after clinical manifestation periods of 2 to 18 h, and 2 sheep survived after being affected for 14 and 46 h. Macroscopic and histologic lesions were similar in cattle and sheep; the liver was swollen and dark reddish, and the wall of the gall bladder was edematous. The cavities had yellowish fluid. Petechiae and echymoses were seen on serous membranes. Microscopically the liver had periacinar hemorrhagic necrosis. Two sheep dosed with 1 g/kg bw daily for 20 d and 1 dosed with 1 g/kg bw for 10 d were not affected. Six sheep were transferred from an area free of W glauca to an area where this plant was present. These animals ate small amounts of the plant and lost weight rapidly, but clinical intoxication did not occur. Two sheep were fed with lucerne hay containing 9% W glauca. They ingested 2.5 g/kg of the dry plant (corresponding to 10 g/kg bw of fresh plant) in 24 h, but did not show intoxication. Because the intoxication occurred in sheep and cattle administered 4 to 10 g/kg bw of the plant in a period of 1 to 2 h, the intoxication may only occur when animals ingest a single toxic dose in a short time.