There is a product called Indoor No. It's a spray and can probably be found in pet stores. Also, I've read that citrus works well.
I have also heard that orange peels will work, but I haven't tried them. I think you will be best served by buying a cat repellent from a garden or pet store. You have to reapply them after a rain usually. Do not use mothballs. They are terribly toxic, &smell much worse than the cat problem. I have had problems with stray cats spraying my house in winter, and I have splashed that area with lemon scented Mr. Clean. This seemed to deter them, and solved the cleaning problem as well.
How can I discourage stray neighborhood cats from "scenting" my entryway? Their urine smell is gagging me. I'm not home to spritz as they visit.
By Mickey from upstate NY
I have had good luck discouraging this sort of behavior by splashing full strength lemon scented Mr Clean on the sprayed areas. Cats do not like a citrus smell, and this has the added benefit of cleaning the area as well.
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