In Brazil sodium monofluoroacetate (MFA) containing plants are represented by 16 species that belong to three principle genera: Palicourea ( Rubiaceae ), Amorimia ( Malpighiaceae ), and Tanaecium ( Bignoniaceae ). These plants can cause acute cardiac failure often referred to as sudden death syndrome. The objective of this paper was to determine if N. stannea contains MFA and to report the clinical signs and pathology of cattle experimentally poisoned by this plant. MFA was detected in all N. stannea plant parts except mature leaves. Niedenzuella stannea was dosed to cattle at single doses of 15-30g kg-1 bw. Clinical signs and pathology observed were similar to those reported by other MFA-containing plants. Animals showed marked tachycardia, labored breathing, muscle tremors, loss of balance, ataxia, falling, recumbence, pedaling movements, and opisthotonous leading to death in few minutes. Gross lesions included engorgement of the large veins, severe lung edema, and petechiae , ecchymosis and suffusions in the pericardium, epicardium and pleura. Histologically, hydropic vacuolar degeneration and necrosis of epithelial cells of the kidney were observed. Cattle that received daily doses of 4g kg-1 body weight for 24 days showed no clinical signs. In summary, this is the first report that N. stannea contains monofluoroacetate and causes sudden death in cattle.

Pesq. Vet. Bras. 34(4):343-348, abril 2014 343 RESUMO.-São descritos os aspectos epidemiológicos, clíni-cos e patológicos de um surto de intoxicação por Pteridium arachnoideum e Pteridium caudatum em bovinos no Estado de Mato Grosso. A distribuição dessas plantas no Estado, a intensidade de invasão de pastagens e alguns fatores associados à invasão das pastagens por Pteridium spp. são Mato Grosso, Brazil, are described. The plant distribution, magnitude and some aspects about the pasture invasion by P. arachnoideum and P. caudatum in the State are also described. Pteridium spp. were found in 83 farms from nine counties and 22 of them were submitted to taxonomic identification. P. arachnoideum was found in 22 farms and in two farms also P. caudatum. Deforestation and burning appear to be associated with pasture invasion by Pteridium spp. On the farm where the poisoning occurred 306 cattle were introduced into a pasture of Brachiaria brizantha intensely invaded by P. arachnoideum and P. caudatum. Twenty two cattle were poisoned by the plants and died. The main clinical signs were hemorrhages, high fever, apathy, fatigue, weakness and recumbency. Gross findings included variable degrees of hemorrhages in several organs and cavities with occasional infarcts. The most consistent histological finding was marked bone marrow aplasia. Epidemiological, clinical and pathological findings associated with the taxonomic identofication of the plant support the diagnosis of acute poisoning by P. arachnoideum and P. caudatum in cattle. The increasing rate of deforestation and frequent burning in Mato Grosso can contribute to this disease which becomes a major cause of economic losses to livestock production in the State. Intoxicação aguda porINDEX TERMS: Poisonous plants, Pteridium arachnoideum, Pteridium caudatum, bracken fern poisoning, plant distribution, cattle.

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