worm counts are useful but i disagree with never worming your horse if they are clear. worm counts only diagnose adult egg-laying worms present in the horse they don't diagnose larvae, especially encysted small redworm larvae which hibernate in your horse all winter emerging all together in the spring and can make your horse seriously ill. worm counts also don't diagnose tapeworm, but there is a blood test available to test for tapeworm.