House-soiling: Trouble Beyond the Litter Box
Unfortunately, cats don't always connect with the litter box. Even cats that know the drill will sometimes choose another spot at home. "House-soiling" can become a concern for even the best cat owners. It can be a sign of a serious health issue or simply the result of changes around the house. Pay close attention for clues to put an early end to a nasty problem for both you and the pet you love.
Signs of a problem:
A pattern of urinating and/or defecating outside the litter box
Urine spraying - evidence of urine marks around doorways, windows or new objects in the house
Spending longer than a normal amount of time in the litter box
Vocalizing while in the litter box
Going to the litter box more often than normal
Health issues ranging from diabetes mellitus to lower urinary tract disease
A dirty litter box or inadequate number of boxes in the home. At least one box per cat plus one is recommended. The litter boxes need to be in different locations in the house - not all in one room.
Litter box is located in a remote, noisy or unpleasant surrounding
Litter box is inappropriate - covered boxes can maintain odors and large cats may not be able to move around enough in small boxes
Wrong type of litter or sudden change in litter type
Social changes, such as the addition of a new cat or the sudden presence of outdoor cats
If you change your cat's litter box infrequently, travel a lot, or have multiple cats at home, you're more likely to experience a "house-soiling" problem. Consider making adjustments based on some of the factors described above. If the problem continues, see your veterinarian to investigate possible health problems.
SOURCE: FLUTD: Thinking Outside (and Inside) the Litter Box - Proceedings of the 2007 Hill's FLUTD Symposium