A snaffle bit COULD be pulled through a green horse's mouth if some sort of emergency arose and the rider took a firm hold of one rein in order to change the horse's direction.
I never liked them, but some riders used to use (may still use?) flat rubber mouth protectors between the snaffle ring and the horse's lips. The only time I tried these, the horse got abrasions on the outside corners of his "smile". I never used them again. If you've done your ground work, most horses are responding well before you are out riding. Nancy
