As part of the process for weaning, a group of 400 calves were given a parenteral injection of a mineral preparation. Four calves were unexpectedly found dead within 24 hours following treatment. Due to marked pulmonary congestion, there was a suspicion of acute pneumonia. Fresh and fixed tissues (liver spleen, lung, and kidney) were submitted to TVMDL for bacterial culture, PCR for respiratory viruses, and mineral analysis on the liver. Cultures and PCR testing for respiratory pathogens were negative. There was no evidence of pneumonia histologically, but the liver had marked necrosis and hemorrhage. Trace mineral analysis on the liver revealed selenium levels of 19.19 µg/g (dry weight). This level is high (normal range is 0.60-3.30 µg/g), and in combination with the liver lesions, is diagnostic for selenium toxicosis.
There is an increased interest in vitamin and trace mineral nutrition in domestic livestock. The concern seems to be primarily with deficiencies, and thus either oral or injectable commercial preparations are utilized for supplementation. This case underscores the potential danger of over supplementation. Selenium can be a health issue for cattle when under and over supplied to the animal. Injectable preparations require closer scrutiny than oral dosing due to the rapid availability of selenium to the animal.
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