Abstract
Four beef cows grazing in a mountainous grassland area had acute onset of drooling, frothy oral discharge, hyperemic mucous membranes, diarrhea, anorexia, dyspnea, and recumbency. Two cows died within 7-8 h of the onset of signs; the remaining 2 cows succumbed 24 h later. Scattered, 3-6-mm, gray-white solids were found on the grassland, suggesting potential contamination. Postmortem examination found abdominal distension, nasal hemorrhage, and distended rumens containing undigested forage. Hemorrhagic lesions were observed in the reticulum, omasum, abomasum, jejunum, and ileum. Yellow, 2-3-mm granular solids were identified in the rumen contents. Toxicologic analysis using scanning electron microscope-energy dispersive X-ray spectroscopy and high-performance liquid chromatography-inductively coupled plasma-mass spectrometry detected high concentrations of trivalent arsenic [As(III), up to 1,070 mg/kg] and pentavalent arsenic [As(V), up to 1,180 mg/kg] in the rumen contents and grassland solids. Elemental analysis revealed magnesium, aluminum, calcium, arsenic (As), silicon, carbon, and oxygen in the residues, suggesting industrial byproducts from As removal processes.