Hi all, for those of you who don't know , I don't have a Blitzan, but I am owned by one, I'm Diva's `monkey'!
Lins with regard to your question, tug of war games will not in themselves create a problem when `work' training your dog. But you have to understand when the dog is in play mode and when it is in work/training mode, and more importantly the dog must be aware of the differences as well. Most dogs are smart enough to learn when your being serious, but as a precaution never mix `toys' with training aids ( dummies) and never play tug of war with dummies or any `valuable' retrieve.
You should also be aware that whilst the game of tug of war may start out as a game especially with young puppies there comes a time where it slips into a serious trial of strength, and I don't just mean physically! Dogs understanding of their position can often change on very subtle things like this, and you often don't realise it till much further down the line, so make sure you win more times than you lose! ( and remember that little ball of fun, will grow into a very fast and muscled hound with a brain to match!) so make sure you know when your at a disadvantage before it happens and pick your games wisely.
Peter