I don't think its aggression. Heidi will sometimes try to swollow things whole if she knows shes not supposed to have....like if she steals some food. I tell her to drop things, and that works, but sometimes its harder when it involves food. I really want to look up that book that everyone is mentioning. It sounds really good. I know what you mean. I've dug stuff out of Heidi's mouth many a time. I've stuck my WHOLE hand into her mouth when she takes something shes not supposed to. Fortunately for me I can open her mouth easily. I wish the best of luck with Jasper. I think that daily training sessions might help too - to reinforce that YOU, and you alone, are the boss. Good luck!