I keep mine in a closet with a hole in the door just big enough for the cats. I tried a covered box but it only made the cats nervous and didn't stop the dogs AT ALL.
You can also get electronic collars (similar to underground fencing) that protect a small radius area, but that seems like overkill.
You can also get electronic collars (similar to underground fencing) that protect a small radius area, but that seems like overkill.