RESUMO
The epidemiological, clinical and pathological findings of field and experimental Senna obtusifolia (sicklepod; coffee senna) poisoning in cattle are described. The low availability of good quality forage and high rate of infestation of pastures by S. obtusifolia were the factors that led to poisonous plant ingestion. In this study, the morbidity ranged between 2% and 27.9%, and the lethality was 100%. For the experimental study, six cattle were fed with the aerial parts of S. obtusifolia collected in three different seasons at 9%-38% of the animal's body weight. The experimental and field diseases were similar. The main clinical signs were diarrhea, reluctance to move, muscular weakness and recumbency. The gross findings included pale discoloration of the skeletal muscle. Microscopically, the affected cattle showed degeneration and necrosis of the skeletal muscles and occasionally of the cardiac muscles. Additionally, two cattle showed centrilobular hepatic necrosis. In this study, S. obtusifolia collected from the same farm showed seasonal variation in toxicity. Poisoning by S. obtusifolia is an important cause of death of cattle in the Central Western region of Brazil. The toxicosis caused by this plant is similar to S. occidentalis poisoning; however, in S. obtusifolia poisoning, acute hepatic necrosis is sometimes present.
