Cats develop a preference for eliminating in certain areas and on certain materials. Litter box problems are associated with 

	preference for material in the box or location of the box
	territorial marking
	avoiding of litter box because it has been associated with something negative
	medical problems
	anxiety

Cats normally have a preference for burying their urine and feces in sand in an out of the way area of their territory. This makes a litter box an easy way to house train a cat or kitten. However, when the litter box training fails or good behavior breaks down it leads to serious problems managing pet cats.

Multicat households have a greater incidence of both inappropriate elimination and territorial marking (when cats spray a couple of drops of urine on upright surfaces). In multi cat households it is critical to find out which cats are involved in the behavior. People have been heartbroken when they give up one cat to solve a problem only to find out that two cats were involved or the wrong cat was blamed.

PREFERENCES
If kittens are properly introduced to a litter pan, they will develop a preference for the location, type of litter and type of pan. This prevents many litter box problems. As a group, cats prefer to use a few inches of unscented, clean, sand litter. Some individual cats prefer a hooded litter pan and some don't like plastic litter liners. Some cats prefer to defecate and urinate in separate places requiring two pans. Some cats will not share a litter pan with another cat. The solution is often more litter boxes, filled deeply and cleaned often, kept in a location that is easy to get to but not disturbed during use.

Moving a litter pan can cause problems for cats. In experiments in which soiled carpets were turned 180 degrees, cats did NOT return to the soiled spot on the carpet but instead continued to use the same spot relative to the room. The smell of the soiled area was not critical to the behavior. Since cats prefer clean litter for elimination, they may even avoid previously soiled areas except in the case in which they are attached to the location. Moving a litter pan gradually, or adding a new box with the old one still in place may help solve problems with attachments to location. If this is not possible, the cat can be confined to one room with the new box and litter for a few days.

TERRITORIAL MARKING

Females in heat and unaltered male cats spray small amounts of urine on vertical surfaces to mark the edges of their territory. Research shows that cats are more likely to mark or "spray" when they are feeling apprehensive about the status of the territory.  Feces left as a territorial marker is often left uncovered. In pet cats it is possible that people are perceived as territorial rivals. In this case, the cause can be new family members or even stray cats outside. This behavior may also occur when a new cat joins the household and the cats work out their respective boundaries. Setting up sub-territories within the house can help establish better behavior.

LITTER BOX AVERSION
Cats avoid litter boxes if the box is not clean. If a cat is frightened during the use of the litter pan, the cat may discontinue going there. Placing litter boxes away from heaters, dryers, rocking chairs and speakers can help prevent disturbances to a cat in the box. If the box is in an inconvenient part of the house, cats may not be willing to use it. Cats will avoid a box when they associate entering the box with pain (see medical conditions). Cats will also avoid litter boxes when they are intimidated by other pets, especially other cats, near the box (see anxiety). 

MEDICAL PROBLEMS
In a case of changes in litter box behavior, a cat should be examined by a veterinarian. Cats may stop using their litter pans if they associate the litter pan with pain or discomfort caused by health problems. If your cat is developing arthritis, she may no longer be willing to climb the stairs to reach the litter pan. When cats suffer from medical conditions that increase their need to urinate, they may begin urinating out of the litter box because the box is not as clean or because the need to eliminate is too urgent to get to the box.  

Mineral crystals sometimes form in the urinary tract of cats. The crystals cause irritation that can predispose your cat to bladder infection. Bladder infections are often associated with inappropriate urination. Bladder infections in male cats are quite serious and can even be fatal if left untreated. Veterinarians used to believe the crystals were caused by too much "ash" and later by magnesium in food. They now believe that a food that creates an acidic pH in the bladder of the cat helps prevent problems. This can also be managed by feeding meat based diets at specific times rather than free feeding dry food. Some people have had success by allowing a cat safe access outdoors or getting a reptile light that provides UVA and B light. Ask your vet if you are using the right cat food for your cat's urinary tract health.

ANXIETY

When illness and litter box cleanliness are not a problem, the most common reason for litter box problems is anxiety. Sometimes, cats become anxious with a change in the household such a new family member or a move to a new home. However, it is also possible that the change in the household just uncovers a long term problem. Opening up a vacant guest room can lead to the discovery of the cat's use of the carpet in the room.

A common cause of anxious urination is intimidation by another cat. Cat social signals are subtle and you may not know that one of your cats feels harassed. It might be as subtle as a more confident cat "playing" with the litter box offender on his way to the box. Cats stare at each other for intimidation as well. You may feel the assertive cat is just lying quietly but the body language of the anxious cat will give away the intent. An anxious cats slinks and increases distance between himself and the other cat. The anxious cat's tail will be held low and ears may be slightly back when the assertive cat is in view. The confident cat will appear to be resting and may even be purring. 

WHAT TO DO:
To alleviate problems, increase the number of litter pans, offer two types of litter. Be sure litter pans are clean and plentiful and easy to access. Restrict cats that share a home with other pets to separate smaller territories to set temporary artificial boundaries which alleviate territorial anxiety. Be sure to restrict the cats to rooms they enjoy and give each their own litter pan. Excluding stray animals from your outdoor property may also help cats feel more secure about their territory. Even indoor cats are affected by outdoor activity. Establish territorial boundaries for new cats to prevent marking behavior and aggression between cats.

To discourage a cat from returning to soiled areas, place a bowl of cat food at the site for several days.  You could also place a litter pan near the soiled area and gradually move it to a new location.

Cleaning soiled areas does not prevent the cat from using the area again. However, the carpet can be cleaned for human satisfaction by soaking the soiled area with club soda, removing all moisture with a shop vac, and treating the area with an enzyme cleaner. Replace carpet padding under the area if possible. If you are having trouble locating the soiled areas, cat urine glows under a black light in the dark. Mark spots for clean up with masking tape. 

Products that may be of help in reducing anxiety are feline pheromones that help cats relax (Feliway), medications from your veterinarian, cat repellants, catnip, and cat toys to assure that cats are getting enough entertainment and exercise.