My 9-month old cocker spaniel has started to get quite mouthy. He doesn't ever hurt us - it's definitely not nipping or biting. I don't want him to think it's ok, but he doesn't seem to respond to "no", withdrawl of hand/food/wrist/clothes, ignoring, distraction with teddy/ball. The only thing he will respond to is a sharp "leave!", but then he goes off and has a big sulk.
Is this just par for the course for a 9-month old cocker? Can I do something else to stop this habit without seemingly hurting his feelings? He's a really sweet pup, but he is sensitive and very sulky if he feels hard done by.