Experimental poisoning by Baccharis coridifolia in sheep

Abstract

The literature contains much information on Baccharis coridifolia DC. (fam. Compositae) in relation to sheep, but there is a lack of basic information concerning poisoning of this animal species by the plant. The reason of this study was to shed more light on this issue. The upper aerial parts of fresh green B. coridifolia were administered orally to 16 adult sheep, in different amounts and at different times of the year. Animals from regions where the plant does and does not occur were tested. The plant used in the experiments was collected in the counties of Itaqui and Uruguaiana, in the State of Rio Grande do Sul. in October/November, when the plant sprouts, 3 to 4 g/kg caused death In sheep, however in March, when the plant flowers and bears seed, 1 to 2 g/kg were sufficient. This means that the plant is 2 to 4 times more toxic during its flowering and seeding stage than during its sprouting stage. The clinical signs were anorexia, isolation from the herd, standing still or lying down, and (with time) remaining in the lying position, apathy, stiff gait, instability, muscular tremors, laborious respiration, lateral decubitus, walking movements of the legs and death. In the experiments where the sheep died, the first signs of poisoning appeared between 3 and 24 hours after administration of the plant. The symptoms lasted between 2 and 42 hours, and the animals died between 23 and 50 hours after having eaten the plant. The major post-mortem findings were lesions of the rumen and reticulum, the epithelium of which could be detached easily with a knife, oedema and congestion of its mucosa, and congestion of the mucosa of the abomasum and the intestine in variable degree. The main histopathological findings were also lesions of rumen and reticulum, necrosis, oedema and detachment of the upper layers of the epithelium, which was infiltrated by neutrophiles, and neutrophilic infiltration in its propria and submucosa.