The other day, someone posted in a forum I read regularly about some changes in their cat's behavior.  They have had the cat for several years, and she is getting to be middle-aged now.  Suddenly she has started acting grouchy toward the other cats in the house, and (they suspect) peeing outside the litter box.

When it comes to unwanted behaviors in cats, peeing outside the litter box is the most common complaint.  What people don't understand is that 1) cats are finicky creatures and their bathroom habits are easily upset by physical problems and environmental changes, and 2) peeing outside the litter box is often your first (and sometimes your only) clue that there is something wrong.

Changes in your cat's behavior could be attributed to a physical illness or injury that is making her feel badly, but it could also be a change in her routine or life that is making her unhappy, uncomfortable, or scared.  For instance, when my husband and his dog first moved in with me and my two cats, one of my cats actually stopped eating because she felt too exposed at her food dish.  The result was that she developed feline hepatic lipidosis, or fatty liver disease, and I spent a month force-feeding her before she could eat on her own again.

If you know there has been a recent change in your cat's life -- you've moved to a new home, gotten a new pet, or started working different or additional hours, for example -- that could be the cause of the changes in her behavior.  But don't overlook the possibility of a physical problem, especially if you can't think of any changes in your cat's life that would cause her to act out!  Cancer can cause a cat to stop eating or act crabby, while a urinary tract infection can cause her to pee outside of the litter box, usually in a different place every time (trying to find a place to go where it doesn't hurt, presumably).  And negative behaviors aren't the only indicators that something is wrong: If your cat suddenly starts sleeping much more than usual, or loses or gains weight, pay attention because she could be trying to tell you something!

If you do suspect that your cat may have a physical problem, take her to the vet as soon as you can.  Your vet can do many affordable tests, such as checking urine for a UTI and doing lab work on a blood sample, that can help to identify the problem.