Keno likes to pick up anything, stones, nuts, tree bark that he finds on his walks. Recently he has been aggressive when I take these things away from him. Before he would let me take what ever and go on to something else. He is eight months old and now he is into challenging me. Any suggestions on how to stop this behavior. If I see the object before he picks it up and tell him to leave it, he does. He will not drop it.
