I would give my gelding the flavored wormers, but they don't have enough choices for the main chemical. I know that parasites can become immune if you use the same type of wormer over and over, so I always make sure to use a different one. I haven't seen too many horses that love to be wormed, infact most of them will try to run if given the chance. To only way to worm effectively is to make sure there is no escape! I also use the sneak attack, I conceal the wormer and give him a mouthful of treats and stick it in real fast. No jerking, pulling, or broken noses lol.