If you have a headstrong dog, petsafe makes an "invisible fence" that don't require burrying a wire.With hard headed dogs, they'll figure out that once they jump the wire, the shocking will stop. With this one, if they go outside the boundary, it keeps shocking until they get back into the safe zone. The unit is adjustable for a certain radius and comes with flags. Once you've set it, the collar will beep when it gets to within 5ft of the boundary. If they go past that, the shock comes into play. I have a buddy that has one and his Jack Russel Terrier has NEVER even thought of going close to the boundary. might be something to look into.