Sharon,
 
The best way I have beat this litter box dumping problem is by taking two
eye bolts, long enough to go through the back of the litter box and have
the "eye" part stick out through the cage (providing you have the type of
cage it can stick through).  My eyebolts are about 1-1/4" long with about
1/4" i.d. eye.  You drill a hole for each, about 6-8" apart, in the
back of the litterbox and secure with nuts on both inside and out of the
litterbox.  Then I bought a metal rod from the hardware store that would go
through the "eye", cut it to fit the distance between the two eye bolts,
plus about 4" longer, and then bent about 2" in a right angle (for a
handle).  This way, you place the litterbox in the cage, the eyebolts stick
through the cage, slide the rod through, no way can they move it unless
they can get out, go to the outside of the cage, and pull the rod out.  But
by that time they're off to bigger and better things to get into.  I've
also used this method for feeding and water dishes that hang on the side of
the cage.  Sure has helped save clean up time.  But it took a while to find
the right combination.
 
Good luck.
 
mjo and the zoo (Phantom, Lady Star, Topanga, Ragine, Bilbo, Frodo,
Frito, Pepper, & Caesar....and the dogs, Garth and Darwin (r.i.p.
Nipper, Lightning, EZ, Cleo and Duke)
[Posted in FML issue 3028]