I second RCS's suggestion on the E-collars. IMO, its the only way to break them from running trash. You need to be able to either see them running the deer in order to correct them right away or set them up by taking them out and intentionally putting them on deer. Let them follow the scent or see them run the deer for about 20 yards, yell, "NO!" and give them a strong correction. It should only take once or twice for them to come running back to you as soon as they smell deer.