It took me 2 sofas to figure this out, but I finally got it --
 
-- I put 2x4s all around the bottom so they couldn't get underneath (due
to the skirt, they liked to go under even after I put panneling on the
bottom, which would have been ok had they not pottied under there too!),
and then:
 
-- I duck-taped strips of plastic carpet protector (cut to about 8" wide)
into each individual crack and crevice: remove the cusions and tape the
strips so the center of the strip is down in the crack, and you have
plenty of overlap for the tape to adhere to.  Crevices are located between
the back and seat, and between the seat and arms, and between the back and
the arms.  Otherwise, they spend all their time trying to dig "new"
tunnels into their hidey-holes!
 
After I did the carpet protector, it took about a week of very grumpy
digging before they gave up entirely.  Now when I get a *new* sofa, I'll
be able to keep it in pristine, un-ferreted condition!
 
Best Wishes,
Melissa
[Posted in FML issue 3762]