I've used a shock collar on our Jack Russell to help with his barking at times and in hopes it would help keep him from jumping the fence. This dog will do anything to get at a bird, a squirrel, or a cat, including jumping straight over a 5 or 6 foot tall fence! I don't know if it's in his breading or what, but he is a hunter. I know my neighbors hate him (and probably me) for him getting in their yards, but I can't put a dog on a chain all day long. It really is crazy to see how high he can jump.