I don't know about hogs, we raised them in pens.
We did raise rabbits in a 30'x30' totally enclosed chicken wire pen. We dug a 3' pit within the whole pen, and laid metal lath through out the pit, and 2' above the pit to keep the rabbits in and varmints out. We filled the pit with dirt, and the rabbits lived under ground. When ever we felt like eating a rabbit we helped ourselves.

Good luck.