definitely tell them the acorns are bad news... and can trigger laminitic episodes with the uncontrolled release of MMP's that Dr.Thomas explains in his article the relationship between natural hoof wall growth and laminitis
http://www.forloveofthehorse.com/hoof_wall_growth.phpIf anyone lives in an area that has a lot of them and its possible for the horses to get to them, I sure would want MMPstop around should one of them have a laminitic episode. A lot would depend on how much the animal eats and likely why some appear to tolerate them - they just didn't pig out.
from Dr.Thomas regarding another case where this happened
Oak acorns contain "tannin" which is very toxic to equids. Tannin kills the surface cells of an animal's digestive tract and enters directly into the blood stream from the gasrointestinal system