Electric Dog Fence
We never recommend you install or use the buried perimeter wireless electric dog fences which are marketed as hidden pet containment systems. (underground containment systems) When using these hidden electric dog fences the dog must wear a special collar that will give an audible warning when the dog gets close to the boundary. If the dog continues toward the boundary they will receive a shock from the collar. There are several concerns with these types of systems. If a dog does escape the yard, it can be deterred from reentering the yard due to the unpleasant shock it experienced on the way out. These unseen fences can cause stress, frustration, and they can contribute to aggression problems. These systems do not prevent or deter other dogs, animals, children, or other persons from entering the yard of an unrestrained dog. To avoid problems with dogs escaping and roaming, do not leave your dog unattended in an unsecured yard.
For more info see: Escaping & Roaming (Securing the yard)