This case study examines a sudden and devastating loss in which five cows and two calves died shortly after being moved to a dry lot following the calving season. The affected group consisted of only six cow-calf pairs that had been separated because they were open or had calved late, making the rapid mortality highly suspicious for a toxic exposure rather than an infectious disease. Necropsies revealed few significant findings, while the only surviving cow showed severe neurological signs, including tremors, vocalization, and an inability to stand.
Investigators focused on feed and water as the most likely sources of exposure and collected samples from the animals, feed, and environment for evaluation. During the investigation, foreign granules were discovered in the feed bunk and were ultimately traced back to agricultural pesticide residue left inside a skid steer bucket. The bucket had previously been used to handle granular pesticide from corn planting operations and was later used to deliver feed without being adequately cleaned.
The pesticide contamination explained the rapid onset of deaths and neurological symptoms observed in the remaining cow. The discussion highlights how potent agricultural chemicals can become deadly when accidentally introduced into livestock feed, even in relatively small amounts. A key takeaway is the importance of maintaining dedicated equipment for feed handling whenever possible or thoroughly cleaning equipment used for agricultural chemicals before reusing it. The case also demonstrates the value of careful history-taking and field investigation, which often provide the answers before laboratory testing is even completed.
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