The most common cause of litter box aversions is a dirty box. If you have not already done so, develop a habit of keeping your cat’s litter box scrupulously clean. Scoop at least one time per day and change the litter completely every few days. Here are a few more tips:

Resolve any contributing medical or behavior problems that may have contributed to anxiety in or near the litter box.
Experiment with other litter types and boxes to determine if your cat has a preferred texture or scent of litter or type of box.
If you have more than one cat, provide one litter box per cat, plus one. If possible, place one litter box in a location that the house soiling cat alone has access to so as to prevent other cats from using it.
Confine the cat to a small room that contains his food, water and a litter box to retrain him to use his box. Until he is reliably using the box, allow him free access to the home only under supervision.

Clean Soiled Areas

Your cat will be attracted back to any spot that he has used outside of his box, simply because the area smells like urine or feces. Therefore, it is important to thoroughly clean all soiled areas using an enzymatic cleaner that is specifically formulated to eliminate pet odors. If the soiled area is a carpet or upholstery, steam cleaning after using an enzymatic cleaner helps to remove all residual odors. Although normal household cleaning solutions may impart a fresh scent to the area, these products mask but do not completely eliminate odors. Although the spot may smell clean to you, your cat’s keen sense of smell will lead to continue to use the spot as an elimination area.

Did You Know?

Medical Problems Can Cause Litter Box Aversions

Cats with urinary tract infections or urinary crystals may urinate outside of their litter box and cats with intestinal diseases such as irritable bowel disease or intestinal parasites may stop using their box for defecation. The problem develops because the cat associates the pain of elimination while he is ill with the litter box.

Solutions for Surface/Location Preferences

All cats develop preferences for the type of surface that they choose for elimination. Luckily for us, the majority of cats prefer to eliminate in sand or dirt, so litter box training comes quite naturally to them! However, when cats stop using their litter box they often develop new preferences during the period that they are avoiding the box. Here are a few tips for changing your cat’s preference back to the litter box:

Block off all access to areas of the house that your cat has been using. If there are areas that cannot be barricaded, make the preferred spots less appealing to your cat by covering them with aluminum foil, citrus-scented cotton balls, or inverted carpet-runner plastic
If your cat has been eliminating on soft surfaces, switch to a litter that is very fine. If she has been eliminating on smooth surfaces, place just a very thin layer of litter at one end of her box, leaving the opposite end of the box bare and smooth.
Add one or more litter boxes, in several locations. (If it is practical, add a litter box to her newly preferred location).