Most horses are already getting Se in other supplements. If you use an
E/Se supplement and boost the E up to where it should be, the horse will
end up being toxic on selenium. Most performance horse should be on an
additional 1000IU/day. Most E/Se supplements are pretty low in Vit E. So
if a horse is already on a E/Se supplement, I have folks buy pure E and
boost more with that. Sorry that wasn't made more clear on my previous
post.
Kim Henneman,DVM