I have three 2-year-old cats. Two of them use the litterbox, and one stopped using it a few months ago. I think the problem started when we were taking care of a friend's cats and there were five cats in the house. How can I retrain her to use the litterbox?
Vicki Ritchie in Fremont, Neb.

Whenever three or more cats live together in a home, the likelihood of housesoiling rises. You didn't provide much information about the specifics of the situation, but the additional cats changed the social structure in the house and may have impacted the cleanliness of the litterbox. Here are some general recommendations for making the litterbox attractive again to the cate not using it.

Behaviorist recommend that in a multi-cat household, you should provide one litterbox per cat, plus one extra. Scoop the litterboxes daily.

Cats prefer a non-scented, granular litter. If given a choice, most cats would choose plain, clumping litter. Fortunately using this type of litter makes it easier to keep the box clean.

Place litterboxes in areas that are readily accessible to the cats and also provide easy entry and exit. Sometimes the places owners like to put litterboxes are not places where cats want to eliminate. For example, laundry rooms can be noisy and scary to some cats.

Make sure that none of the cats are "guarding" the litterbox and preventing ready access. Cats must feel that it is safe to use the box.

Add a product to the litter that is designed to make the litterbox more attractive to cats.

How are you cleaning up the areas where the cat eliminates? If you do not use an effective, enzymatic cleaner, the cat will return to the same spots. If carpet is involved, pour the cleaner on the carpet so is soaks into the pad below; this is where most of the odor resides. For repeated episodes of urination in the same area, you may need to replace the carpet and padding to remove the odors.

Can you put a litterbox in the cat's preferred elimination spot? If not, consider placing solid air fresheners nearby. Cats like their own smells, but other fragrances tend to repel them. Another consideration is to confine the problem cat in a small room with her own litterbox for a couple of weeks - when she is unsupervised - to get her back in the pattern of box use.

Synthetic pheromones may be helpful. Pheromones are used by cats to mark their "good zones". Spraying synthetic pheromones on the area of innappropriate elimination should discourage the cat from urinating in these areas again.

The longer a housesoiling problem exists, the longer it can take to extinguish. It is difficult to make more specific recommendations without a detailed history. Consult a veterinarian with experience dealing with housespoiling issues or contact a behaviorist to get more ideas and options to solve the problem.

Elaine Wexler-Mitchell, DVM (from the May 2006 issue of Cat Fancy)