We have a spayed female that is almost 10 years old. In the last couple of years, she has started a nasty habit of urinating on anything within her reach that has a vinyl or plastic smell: shopping bags, backpacks, purses, coats, shoes, suitcases, rubber backed throw rugs, etc. In talking to my sister and a friend, both of them said their female cats do the same thing. Why does she do this, and what can be done to stop her? I've had the vet check her for urinary tract infections, and she's fine.