Join Date: Mar 2012
Location: Whidbey Island Washington
Your options boil down to these: Separate him, get rid of him, get rid of the other horses. Not ragging, but that's really all the advice you're going to get. I'm not trying to rag on you. Beg, borrow or steal (being facetious there) what you need to separate that horse, or you really need to consider getting rid of him.
Also, it doesn't matter how many of the horses are fine, the fact that there is one who isn't means that children shouldn't be allowed in there. If the pony needs to be removed, catch the aggressive horse first so the child (or preferably a parent) can remove the pony. If the child gets hurt, it won't matter a whit that all the other horses were fine.