I'm so sorry you're going through this with Ham. I don't have any experience with aggression, but think you have the right instinct regarding his change in behaviour. I'm not sure what would cause this, but I don't think teeth removal would cause a dog to be aggressive. If anything, I'm assuming his teeth were decayed and that's why they were removed, and if he was having pain from his teeth, that could cause aggression or change in behaviour, but since the teeth have been removed that wouldn't be the case now. I agree with your suspicions that it could be a part of the aging process, and also your friends Husky. The Husky has been acting aggressive to Ham, he's gone from being an only dog in the house to sharing his space with another dog, and also a new person in the house. Our Bullies are so OCD, and any change in their routine, environment or surroundings can cause them stress. You also mentioned that you think his eye sight is failing and so maybe he gets startled more easily, when someone or something approaches him, and he can't see it properly, so he reacts with fear and stress, and his natural instinct is to act aggressively by lunging and or biting. He is showing stress and fear. Is he loose in the office? Maybe if he had a crate at the office in a quiet area, where he could be when a vendor came in, and then be loose when you are alone in the office, it would help. I hope when your friend and her dog move out, things settle down, and if it doesn't work out at the office, then he could maybe be left at home, since he will have the house to himself again. I hope things work out. Please keep us posted.