Feliway is a GOD SEND in my house!!! I took in Bad @$$ Buddy a couple of years back and he began peeing all over my tiny apt. The vet ruled out a UTI and gave me Feliway Concentrated Spray. It worked like a charm!!! The defusers do not work as well, in my opinion.

Take it from someone who has kept a can in her house for a long time (along with the Cornell Book of Cats). It works!!!!! You just raise your arm over your head, shake the can well, and spray the circumfrence of the rooms. There's an enzyme in it that works IMMEDIATELY!! I highly recommend it to anyone. They also have "behavior collars". Not sure how they work.