I have a 3 year old Chihuahua,he was toilet trained from a puppy but since hes hit 2 hes started marking in the house.Its usually the same spots in the kitchen which I clean with bleach and a special dog urine spray.Nothing works and I really regret not getting him castrated years ago.Do you think it would stop him if he had the operation now? Hes nearly just weed on my leg and has never done this before.