[Jean S]

I owned horses for years in Wisconsin. Selenium is low in our soil so we always used vitamin supplements that included selenium and I have never heard of an overdose or even of any side affects.
Someone messed up, either accidentially or intentionally.

[vetvetdoug]

NE Ms is an area of low Se in the soil. We have to augment Se in the diet or we get white muscle disease in cattle and reproductive and muscular dysfunction in horses. I have heard of Se toxicity but it is quite rare..this had to be some kind of major screw up in the mathematics department of the pharmacy.