I am no pro here, I am training my first lab. But from what I have read and from what people have told me about this exact subject. When you are throwing a tennis ball or other toy it is fun for the dog because they do have to stay at sit or heel they are just running around having fun. When you throw bumpers you make them stay at heel and break when you release them making it work, when they bring the bumper back to you take it from them and throw a "happy bumper" one that they are not at heel, this will keep it as a game and they will want to bring it right back to you because they might get a fun one.
Your pup might also be a very proud dog, this was my problem, once they get something in their mouth they are very proud of themselves and don't want to give up their "prize". Try throwing a mark and when they are on their way back start running backwards once they get to you stop and run forward for awhile letting the pup keep his prize for awhile that way he doesn't think that everytime he gets that bumper in his mouth you are going to take it from him.
Like I said I am no pro at this but these are some of the ideas that have been thrown out to me for this problem. Hope it works for you. Good Luck
Scott
Your pup might also be a very proud dog, this was my problem, once they get something in their mouth they are very proud of themselves and don't want to give up their "prize". Try throwing a mark and when they are on their way back start running backwards once they get to you stop and run forward for awhile letting the pup keep his prize for awhile that way he doesn't think that everytime he gets that bumper in his mouth you are going to take it from him.
Like I said I am no pro at this but these are some of the ideas that have been thrown out to me for this problem. Hope it works for you. Good Luck
Scott
