Cats will pee outside the litter box if the litter box is dirty, so make sure you're scooping the littler box everyday and once a week, clean the litter box itself with soap and water and put new litter in.
Also, sometimes cats are very picky about the litter itself. I use Arm and Hammer and my three cats like it. Also, the problem could be medical, like a urinary track infection.
The animal associates the pain with the litter box itself and will stay away from it. Go to a different vet and rule out a urinary track infection first. Good luck [url=http://kitty-whisperer.com/18WaysToStopCatUrineOdorReview.html]cat smells[/url]
