My 9 month old Leonberger has started to mouth my wife. He is not an aggressive dog at all (he surrends to jack russels in the park!) he does not bite or close his jaw but mouths my hand, legs and arms... He'll do this at home, while we're out on walks etc... I've read that this is dominant behaviour. I'm taking him to puppy training classes already but is there anything else i can do to stop this kind of behaviour?