Cattle poisoning by Baccharis coridifolia – report of an outbreak and a brief review of the literature

Abstract

Baccharis coridifolia is a toxic weed from southern Brazil and regions of Argentina, Uruguay, and Paraguay. In Rio Grande do Sul (RS), B. coridifolia occurs mainly in fields bordering Argentina and Uruguay (Campanha). Poisoning by B. coridifolia occurs in cattle, buffalo, sheep, and horses. The disease is often fatal after an acute course characterized by gastrointestinal disturbances. We report here the epidemiology, clinical, and pathological aspects of an outbreak of B. coridifolia poisoning in cattle that occurred in a herd of 70 heifers transported from the municipality of Bossoroca (28° 43' 48" S 54° 54' W), RS (Property 1), to another property in the municipality of Júlio de Castilhos (29° 13' 37 " S 53° 40' 55" W), here referred as Property 2, 180 km away from Property 1. Upon arriving at Property 1, the heifers were placed in a paddock of native pasture, which had a shortage of forage and a moderate amount of B. coridifolia. The next day, three heifers were found dead, and the others were transferred to an oat pasture, where 36 died, many without showing evident clinical signs. Out of 70 heifers, 39 died, and three were necropsied. The main gross changes were in the gastrointestinal tract. The ruminal contents were abundant and liquid; microscopically, there were degeneration and necrosis of the epithelium of the pre-stomachs and abomasum; these changes were more pronounced in the omasum. The final diagnosis was based on epidemiological data and pathology. Although B. coridifolia is found mainly in the Campanha region of RS, this outbreak indicates that it should also be considered in the differential diagnosis of acute death in cattle in the midwestern region of the State.