Preventing and Correcting Litter Box Problems
The most common behavioral problem reported by cat owners is that their cat urinates and/or defecates outside of their litter box (Borchelt & Voith, 1996). However, there are several steps that you can take that will usually correct your cat's problem litter box behavior.
The first step is to make sure you have enough litter boxes. It is recommended that you have one litter box for each cat in your household, plus one extra. Cats don't like sharing their litter box with other cats and will sometimes refuse to use a box that someone else has already used. This doesn't necessarily mean that cats in multiple cat households will claim one box as their own and use this particular one consistently, but at least if you have multiple litter boxes then if one litter box has been used then the next cat that needs to use the litter can choose to use a different box.
Make sure you keep the litter clean. You should scoop out the litter box at least once a day and completely change the litter about once a week if you are using scoopable litter, and more often than this if you are using clay litter. Remember that cats have a much greater sense of smell than humans do and so if you can smell the box then the litter is overdue for a litter change. In general, the cleaner the litter box the more likely it is that your cat will use it.
According to Borchelt and Voith (1996) it is possible that your cat may not like the design of the litter box itself or the brand of litter. Changing the brand of litter is probably the easiest of the two and so I'd try that first before buying a brand new box. Some cats don't like the smell of a particular brand or the feel of it. If you have more than one box you could try a couple different brands to see which one your kitty prefers. There are numerous types of litter (e.g., clay, scoopable, crystals, and wood chips). Please note it is important not to use scoopable litter with young kittens because it can block their intestines if they ingest it, which can be fatal. Check with your veterinarian as to what age kittens may safely use scoopable litter.
Once you have implemented the above steps, if your cat is still eliminating outside of the litter box you can also try moving the litter box to a new location. Cats like privacy when they use the litter and if the litter box is placed in a high traffic area then your cat may not want to use it. Also, your cat may have grown accustomed to eliminating in an area outside the litter box and you need to make the inappropriate elimination area as unappealing as possible. This area should be thoroughly cleaned and deoderized with a cleaner specifically for use with pets such as Nature's Miracle or Woolite's Pet Stain. Be sure to read the directions and precautions for use around pets. Also, if your cat has been eliminating in one specific area outside of the litter box then covering this area up so your cat no longer has access to it may help.
There are some other reasons why cats may not use the litter box properly, especially if the cat suddenly stops using the litter and starts eliminating in an inappropriate location. I once had a cat that suddenly started urinating in the bathtub and on the floor. I took her to the vet and it turned out that she had a bad urinary tract infection and that was why she was urinating in inappropriate places. The vet started her on an antibiotic and my cat started using the litter box properly again within a couple of days. Anytime your cat suddenly changes his or her litter habits you should get your cat to the veterinarian to rule out a medical problem.
Finally, when your cat does use the litter box properly you should positively reinforce him or her. This consists of praise and perhaps a treat that your cat enjoys. Punishment, such as yelling at your cat, and rubbing your cat's nose in the excrement has not been shown to work. This usually just leads to depression in your cat.
Marder and Engel (2002) conducted a research study in which they recruited cat owners who had cats that consistently urinated and/or defecated outside of the litter box. They had the cat owners implement the above mentioned tips (e.g., correct number of litter boxes for household, clean litter, changing brand of litter to something kitty likes, cleaning and covering up the inappropriate elimination area, positively reinforcing cats for properly using the litter). Then after 12 to 54 months Marder and Engel contacted the study participants to ask about their cats' litter behavior. Marder and Engel found that 47% of cat owners said their cat's elimination problems were cured, 26% said their cat's litter behavior was much better, 14% reported their cat's litter behavior was slightly better, Only 13% of study participants reported that their cat's litter box problems were the same or worse. So you can see that most of the time these methods do work in resolving problem litter box behavior.
Borchelt, P. L. & Voith, V. L. (1996). Cat elimination behavior problems. In V. L. Voith and P. L. Borchelt (Eds.), Readings in animal companion behavior (pp. 179-190). Trenton, NJ: Veterinary Learning Systems.
Marder, A. R. & Engel, J. M. (2002). Long-term outcome after treatment of feline inappropriate elimination. Journal of Applied Animal Welfare Science, 5(4), 299-308.