Cats tend to be alert, somewhat nervous animals who can react with fear to a number of situations, and this can result in inappropriate. Being 'fraidy cats' has helped cats to survive in the sometimes hostile natural world where they might make a tempting meal for a larger animal.
Although living with humans has undoubtedly softened some of the cat's natural skittishness, they still depend upon instinct to keep them safe, and often appear to us to overreact.
There are a number of reasons why a cat might be avoiding the litter box, such as an infection, or a dirty box. However, fear can also be responsible for litter box avoidance and in soiling inappropriately, and this could well be the case with your cat.
Why Your Cat Might Be Afraid of the Litter Box
The fear your cat might be showing as avoiding the litter box could stem from his or her fear of the box itself, or of the place where the box is situated. If your cat associates a certain spot in the house with an unpleasant or traumatic experience, it could cause your cat to mess outside the litter box. Cats have good memories and will associate the litter box with the incident long after the 'danger' is gone. If simply moving the box is not an option, there are ways to help your cat overcome his or her fears.
Most cats who develop a fear their litter box because of past trouble in the area can be helped to overcome this with patience and kindness. Never punish your cat for messing on the rug or behind a chair, it will only make the animal more nervous and less likely to use the litter box in the future.