Perirenal edema and toxic nephrosis in cattle, associated with ingestion of pigweed.

Twenty-two young cows died or were euthanatized after intoxication associated with ingestion of redroot pigweed (Amaranthus retroflexus) growing in marginal grass pasture. After several days of weakness and posterior incoordination, the cattle became recumbent but remained alert. Pertinent clinical laboratory findings included increased blood urea nitrogen content and marked proteinuria. At necropsy, perirenal edema and toxic tubular neprosis were seen.