title: Amorimia exotropica poisoning as a presumptive cause of myocardial fibrosis in cattle.
abstract: The current study reports the investigation on the cause of sudden deaths associated with cardiac fibrosis in cattle in northern Rio Grande do Sul, Brazil. The exclusion of known causes of bovine cardiac fibrosis as well as the absence of the plants in that region whose consumption has already been linked to the disorder motivated this investigation. The condition, which was attributed to the consumption of Amorimia exotropica, affected draft oxen, most of which died suddenly without showing any clinical signs during usual management or work. Globular hearts with white foci at their cut surfaces were the main gross findings, which corresponded microscopically from multifocal to coalescent areas of myocardial fibrosis. To confirm the condition, A. exotropica from the ranches where cattle died from the disease was dosed to rabbits, which showed similar lesions to those seen in dead cattle after receiving 10 doses of 3.6 g/kg at 4-day intervals. Electron microscopy on rabbit tissues revealed severe tumefaction of the cardiomyocytes associated with mitochondrial swelling, displacement, and rupture of the mitochondrial crests, and of the bundles of myofibrils, apart from large glycogen deposits within the sarcoplasm. It is suggested that mitochondrial changes triggered alterations that lead to cardiac fibrosis and that all of these changes were induced by A. exotropica cardiotoxicity.
authors.affiliation: Laboratório Regional de Diagnóstico, Universidade Federal de Pelotas, Faculdade de Veterinária, Pelotas, Rio Grande do Sul, Brazil.
authors.forename: Mauro Pereira
authors.initials: MP
authors.lastname: Soares
authors.forename: Saulo Petinatti
authors.initials: SP
authors.lastname: Pavarini
authors.forename: Maria de Lourdes
authors.initials: Mde L
authors.lastname: Adrien
authors.forename: Pedro de Souza
authors.initials: Pde S
authors.lastname: Quevedo
authors.forename: Ana Lucia
authors.initials: AL
authors.lastname: Schild
authors.forename: Paulo Vargas
authors.initials: PV
authors.lastname: Peixoto
authors.forename: Cláudio Estêvão Farias
authors.initials: CE
authors.lastname: da Cruz
authors.forename: David
authors.initials: D
authors.lastname: Driemeier
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000139:chemically induced*; D003645:Death, Sudden / Q000662:veterinary; D005355:Fibrosis / Q000139:chemically induced / Q000473:pathology / Q000662:veterinary*; D006331:Heart Diseases / Q000139:chemically induced / Q000473:pathology / Q000662:veterinary*; D029581:Malpighiaceae / Q000009:adverse effects*; D010947:Plants, Toxic / Q000633:toxicity*; D011817:Rabbits