Poisoning by Amorimia (Mascagnia) sepium in sheep in northern Brazil

Abstract

The aim of this study was to determine the cause of sudden deaths in sheep in the Anari Valley of the state of Rondônia, in northern Brazil. In one outbreak, sheep were placed in an area where the owner had cut Amorimia (Mascagnia) sepium and let it dry for two days. Fourteen out of 35 sheep died with few outward clinical signs observed over a period of about 10 h after the ingestion of the dry plant. Dry A. sepium was administered experimentally to 9 sheep. Five died after the ingestion of single doses of 3-6.6 g/kg body weight (bw). Two sheep died after the ingestion of total doses of 6.4-31 g/kg bw over the course of 4 and 5 days, respectively, and one died after being treated with 33 daily doses of 0.56 g/kg bw. Six sheep died during exercise, and three died without exercise. Clinical signs were anorexia, muscular tremors, dyspnea, jugular engorgement, tachycardia, apathy, opisthotonos, foam in the nose, and recumbency. One sheep, which ingested a single dose of 1 g/kg bw, was not affected. The main macroscopic lesion was pulmonary edema. Histologic examination of the heart revealed degeneration and necrosis of cardiomyocytes, as well as multifocal inflammatory infiltrate of mononuclear cells. Fibrosis, neovascularization and infiltration by mononuclear inflammatory cells were observed in the sheep that ingested the plant for 33 days. Vacuolar-hydropic degeneration was observed in the epithelial cells of renal tubules of four sheep. It is concluded that A. sepium is responsible for sudden deaths in sheep.