We put Tuna on Amitriptyline last week for his spraying. They said it takes a few weeks to kick it, but I've already noticed a difference. Every morning I would wake up and Tuna would run right to the front door and spray. He was spraying several times a day all over the house. If he meowed and you didn't pet him or feed him right that second he would run off and spray. Since we've put him on this I've only caught him spraying once, and that was last week. Other than that he still seems to act normal, we were afraid that we would lose his goofy personality but it's still there. The vet gave us Amitriptyline first because it was the least expensive medicine, if it stops working then we'll give prozac a try.