Clean the litter box daily and provide the cats with multiple litter boxes . Sometimes a cat simply dislikes the litter. Many cats are repelled by perfumes or deodorizing pellets found in litter. If the cat won't use the litter box, try other different types of litter . Perhaps one will have the right texture and scent to bring the cat back to the box.
Location can be another cause of litter box problems.
Most cats are modest and prefer to do their business in solitude and peace. If the litter box is in the center of the living room or next to the washing machine, chances are it won't get much use. If it appears that a cat's behavior cannot be corrected by litter box alterations, a more in-depth look is in order. Most cats will dig in litter material, whether indoors or out, before eliminating. According to Dr. Voith, if an owner watches for this behavior and interrupts it before the cat eliminates, the cat may learn to change its behavior.