Poisoning by monosodium methanearsonic acid (MSMA) is reported in a herd of 24 Girolando cows that were introduced into a pasture sprayed with the herbicide. Clinical signs were apathy, anorexia, and profuse diarrhea. Fourteen cows died and two were necropsied. Abomasal ulcers and renal congestion was observed. Main histologic lesions were multifocal, accentuated, necrotizing and hemorrhagic abomasitis and omasitis, and tubular necrosis in the kidneys. Mean arsenic concentrations in cows with clinical signs were 1.19±0.40, 10.52±2.16, and 76.06±48.37ppm in blood, milk, and feces, respectively. In the two necropsied cows arsenic concentrations were 25.58 and 23.85ppm in liver, and 28.71 and 35.94ppm in kidney, respectively. In a fetus of a cow that was necropsied, arsenic concentrations were 9.0 and 8.92ppm in liver and kidney, respectively. Arsenic concentration in the grass collected from the paddock sprayed with MSMA was 111.58ppm. In Brazil, the use of MSMA in the composition of herbicides is allowed only for agricultural use, not for livestock. The use of arsenic based products for livestock can lead to high mortality rates in the herd, as well as reduced production and contamination of animal products.
Poisoning; herbicide; arsenic; monosodium methanearsonic acid; cattle
