I have the sweetest little Cavalier King Charles Spaniel that we adopted this summer. He's 4yo & not fixed. We were planning on getting him at the end of the summer since we knew we would be gone for vacations. Well he just fell into our laps & we couldn't say "no" (who could?). So we had him for a week before we left on vacation for a week (does this make sense?). When we got back he started marking all over the place! I don't know how to make it stop. I've heard that we should get him fixed...others say he's too old for it to help. What do I do?