Electronic dog fence

As mentioned, many high energy dogs will run right through an electric fence, because they figure out quickly that the zap is temporary. However, they won't come back in the yard because they don't want to get zapped again. Other dogs become very paranoid about them and will refuse to go outside or anywhere near the fence, especially if they've been previously zapped.

The greatest danger is not being able to control who or what comes into your yard, possibly rendering your pet defenseless.