Cats are certainly not social in the same way that dogs are, but their behavior patterns have certainly been changed over their long association with humans. Strictly solitary in a natural setting, cats now enjoy not only the company of people, but often that of other cats. It’s not unusual to see a pile of cats sleeping happily together. However, you should always keep in mind that cats do need a bit of space and privacy as well. Households with multiple cats often suffer from litter box problems where one or more of the felines soils inappropriately.

Pinpointing the Culprit

Once one of the cats starts avoiding the litter box, it’s important to try to find out which one it is. The problem often arises because one cat is dominant over the others and will attempt, often successfully, to keep the other cat, or cats, from using the litter box. Fights can actually follow as the dominant cat ‘repels boarders’. In most cases, the cat who is lower on the social spectrum will be the one who is the inappropriate eliminator. Refrain from punishing the guilty party, neither the dominant cat nor the one who is urinating on the rug; just find a solution as quickly as possible.

What to Do

It’s not too difficult to overcome litter box avoidance in a multi-cat home, especially if you approach the problem through the eyes of your cats.
The most obvious solution is to provide several litter boxes for the cats, placed at a distance from each other. Cats enjoy some privacy when using the box and a dominant cat will have more trouble enforcing his or her position if the boxes are separated.
Dirty litter boxes invite cats to avoid them. Keeping the boxes clean will encourage the cats to use them.
Observe your cats and see the spots each cat enjoys most – this will be the best place to put a litter box.
Do not situate litter boxes near where the cats eat and drink; this is especially important when you are adding new boxes.
Use an enzyme cleaner to remove all traces of urine and feces from places where accidents have occurred. Cats will be attracted to the smell and consider the area to be a latrine.

Always keep in mind, too, that after discovering who is not using the litter box to have the culprit examined by your vet just to make sure that no medical problem is present.