Some cats may urinate on horizontal surfaces such as carpets, furniture or other such items. This behavior may also be caused by territoriality, but might also be a symptom of anxiety. If your cat has recently begun having litterbox problems and medical causes have been ruled out, try to think of any possible causes for the behavior. You must think like a cat. Remember your cat is not trying to spite you, but he or she is merely trying to communicate.
Some older cats find it difficult to climb into the litterbox.
Consider using a box with low sides to help minimize the effort required to enter the box. If so, attempt to limit roaming cats' access to your yard. If this is not possible, keep drapes closed when other cats are around. Such odors can cause Fluffy to mark his territory. Studies have shown that the frequency of litterbox problems increases proportionately with the number of cats in the household.