Try a Different Box
An enclosed litter box may fit nicely within your decorating standards and help contain the mess and odor, but your cat may not agree. Enclosed boxes can be small, dark, smelly and difficult to turn around in—not conducive to cats doing their business. You also want to make sure the sides of your litter box are low enough for your cat to easily step over—especially as he reaches old age.
The ideal litter box is large, open, and has low sides or at least one low spot to ease access. It can be difficult to find litter boxes that have these characteristics in pet supply stores, but they are easy to make using plastic under-bed storage boxes.