We have a dog that was dropped off at our house a few years ago. She was probably abused before coming to us because everytime she comes in the house, she goes into a total meltdown. So she stays outside and is very happy there as long as she is free to run around. No fences for Missy - she climbs over, digs under, and has learned to open doors. We have 20 acres of land but she will not stay on our land - she wants to go and play with the neighbor's horses. He's a very mean man and has sent her to doggy jail -- even lied to me when I asked if he had seen her. So in order to keep her safe, we use a wireless collar. It operates just like the bark collar. It works very well for her. She gets a beep before she gets a shock. The beep is about 10' before the border. She turns around and comes running back. It only took being shocked once to teach her!!
This neighbor threatened to shoot her if she ever set paw on his property again. I have no doubt this has kept her safe from him!!!
My daughter has boxers and uses the shock collar to keep them from jumping on people. Again, once was all it took. The collars don't even work anymore they put them on the dogs when I come for a visit and they do not jump on me. They are so sweet and just walk up and sit and wait to be petted.
We've had very good experiences with these.