There\’s your first problem. Cats are very clean by nature — in addition to regularly cleaning out the entire thing, you should be scooping at least every day. I admit I am really bad about this myself. The general rule is that most litterbox problems are psychological–they either don\’t like the condition of the litterbox or they don\’t like the location (too loud, too dark, too busy, smells odd, etc). Try scooping every day for starters. If there is still a problem, find a new location for the litterbox (make sure he knows where it is) and see if that helps. The tip about not using strong-scented cleaners when you\’re cleaning it is a good idea, too, as well as the possibility that he might not like the enclosed feeling with the lid.
I\’d be willing to bet that it\’s a psychological issue that he has with the litterbox, and a few modifications in its cleanliness and possibly location will solve it. I went through this about 2 years ago with one of mine–she decided I wasn\’t scooping it often enough for her and started pooping right in front of it. I started scooping every day and it eliminated (hah) the problem.
Observe the cat and notice if he is straining to go and/or crying out.
He may claw out a space in a potted plant, choosing clean dirt over a soiled litter box. Or he may squat on your carpet or floor because he associates the sensation of digging in litter with uncomfortable elimination. If you confine him to a closed room with a clean litter box and he ignores it, he may have no control over his actions. This signals that illness, not behavior, is the culprit. The cat is in pain, and your vet needs to determine why. A thorough checkup will reveal whether Kitty has a urinary tract infection, inflammatory bowel disease, diabetes, arthritis, kidney, liver or thyroid malfunction or other illnesses that may affect his litter box habits.
If illness, minor or serious, is the cause, medication or treatment should relieve his pain and distress. Whatever has pushed your cat out of the box, getting him back on track will take patience. If anxiety created the problem, set up a quiet retreat for the cat to do his business in a room or area with minimal household traffic. Provide a large-enough litter box — or two — with the kind of litter your cat prefers, and change it frequently, even several times a day if necessary. You may decide to confine him for a few days to establish a new, calmer routine.
Inflammatory bowel disease, constipation, diarrhea or urinary tract infections will abate with medication or treatment, so if one of these caused your cat\’s problem, he should return to using his litter box as his discomfort eases. Longer-term conditions, such as arthritis or kidney problems, may mean making adjustments: Be sure the cat\’s box is low enough for him to get into comfortably, and offer more than one box to accommodate more frequent usage. Always keep the litter boxes clean by washing and disinfecting them weekly and quickly removing soiled litter.