When you buy a doggy electric fence, it's just some stakes and a wire, not really a "fence". You hang the wire about 10-18" from the ground (depending on the size of the dog -- you want it about chest height because a shock on the nose would probably hurt.) It's not even very noticeable. I wired off a little 2' x 9' garden of vegetables.

After a couple of months, even the stupid one (who had to get shocked pretty much daily for weeks to get the message) wouldn't go anywhere near a piece of bare wire, and I left the fence up but turned it off :) Later we expanded and just strung up some wire...

Feeding some root vegetables sometimes helps instinctual digging behavior, but not once it's a diehard habit that they've learned to do it out of fun. And if they think it's fun, a little 6" fence is NOT going to deter them!

Ain't dogs grand?