Be Aware of Behavioral Changes
It is through careful observation that we discover the clues that can solve litter box avoidance problems. No one is in a better position to make these discoveries than you. You know your cat's unique personality and behavior patterns better than anyone else, because you live with him. Take the time to notice his behavior in and around the litter box. It will give you an idea of how he feels about his toilet. If he spends as little time as possible in the box-with hardly any digging or scratching in the litter-it could be that the substrate is offensive to him. If he uses the litter, but proceeds to scratch on the floor outside of the box, he may find the litter box too small to accommodate this natural behavior.
Kirsten Kranz, Cats International's coordinator for the Racine/Kenosha Behavior Hotline, frequently handles challenging housesoiling cases. Recently she received a cat from another state that had come to the attention of a caring individual who wished to save this friendly and unusual feline. Matt (Kirsten's name for him) was born with a severe deformity. He has no lower legs or paws. He is amazingly proficient at moving himself around using the upper portion of his legs. Other than his locomotion problem, he is in all respects a normal, healthy, happy, affectionate cat. He actually lived outside until he was discovered by a woman who kept him in a cage for several months, where he virtually lived in his litter box.
When Matt arrived at Kirsten's home, he had no idea that the litter box was the only designated spot for elimination. By understanding his history and carefully observing his substrate preferences, within a week Kirsten managed to train him to use the litter box exclusively. She discovered that he did not like to eliminate on the bare linoleum floor, but he would occasionally use the sandy substrate in the easy-access litter box she provided for him. He would also eliminate on anything else that was left on the floor. By temporarily confining him to an area with only the bare floor, his litter box, bed, food and water, she has successfully conditioned him to use his litter box reliably. Matt is well on his way toward becoming an adoptable pet.
Special Consideration
Some cats, like Matt, have special needs and deserve extra consideration. For example, particular attention should be given to the unique problems of longhaired cats, who may periodically find bits of stool sticking to their fur and may avoid the litter box for that reason. They may also be disturbed by the fine-grained litter clinging to the tufts of fur on their paws-in which case they might be happier with a different textured substrate. (Trimming the fur in the problem areas may be all that is needed.) Declawed cats may also require special considerations, as lingering paw sensitivity may force them to seek out smooth or soft surfaces for elimination purposes.
Whatever the reason for the inconsistent use of the litter box, with a little work and a little patience, it can be solved!
Betsy Lipscomb is a feline behavior counselor and president of Cats International, where she works intensively with the Feline Behavior Hotline.

