Talk to your vet about a drug called Clomicalm. It is used to treat dogs w/behavioral problems but has been used successfully w/cats. I've had some of my Fur Posse on it for years. Some vets will tell you that it may take as long as 8-12 weeks to work but I was fortunate to have it begin working immediately. I have them tested once a year to make sure there are no complications and there have never been any. There is no change in their personalities either. My cats get 5 mg. before bed and I've seen no spraying incidents since then. Some other PTers use kitty Prozac instead and have seen good results w/that. I've never used it because I haven't felt the need; Clomicalm works very well for me. In the meantime, use a good enzyme cleaner where your cat has sprayed to completely remove the odor and stain. I use Urine Gone and it can be purchased at Bed Bath and Beyond and other stores, even online. Good luck.