Selenium toxicosis in feeder pigs

Selenium toxicosis was diagnosed in feeder pigs on a central Michigan farm. Use of a commercial supplement, found to contain approximately 20 times the intended Se concentration, resulted in a Se concentration of 8.1 mg/kg of the complete feed. This was fed for 34 days during which daily feed consumption decreased approximately 35%, several pigs developed weakness and forelimb paresis, and 1 pig died. The highest serum Se concentration measured was 1,550 ng/ml (normal range, 140 to 190 ng/ml). Normal feed consumption returned when an alternative feed was provided. Mean serum Se concentrations of representative pigs, monitored over the subsequent 26 days, decreased from 905 to 258 ng/ml. Histologic examination of a recovering pig revealed skeletal and cardiac myopathy and bilaterally symmetric malacia of the gray matter of the ventral horns of the spinal cord. During the developing toxicosis, the pigs consumed an estimated 11.4 mg of Se/pig/d.