Having a bad experience while using the litter box can lead to messes in the house, Gaughan said. Also, if the cat has been startled while using the litter box, it may find other places to eliminate. For example, the cat may become frightened by the noise of a washer, dryer, water heater or air conditioner. The cat may then associate that with using the litter box and may choose a quieter location. Having more than one cat in the household can also lead to problems with using the litter box, Gaughan said.
Adult cats define their territory.
Often there's not enough room in the house and the cats' territories overlap. Gaughan said this can lead to territorial anxiety and the cats may begin spraying urine to better mark their territory. The cats are doing the same thing they would do in the wild if they were forced to live in such a small area. Or the cat may avoid the litter box for the simple fact that it wants the box to be cleaner or it doesn't like the type of litter used. The litter box should be scooped daily and the entire litter should be changed once a week.