For dogs that are fearful when people come to the house, the dog can be isolated at first, then once everyone is seated, the dog can be brought into the room and restrained on a leash with a head halter attached. If this approach is employed, the dog should be removed from the room before the guests prepare to leave, in the early stages at least.
Once the dog is relaxed with people quietly sitting in the home, he should be taught to remain calm when people move around in the home. Dogs that have fear-driven aggressive behavior have a tendency to snap at people when they are moving away. Start by having the guest slowly stand up and then sit down again. Reward the dog for not reacting. Next have the person stand up and sit down more quickly, and so on.
If all goes well, the person can progress to taking a few steps around their seat. Gradually, increase the amount of movement the dog can tolerate while remaining relaxed. Reward each step in the right direction with food treats.
It is not a good idea to have the person attempt to pet or reach out toward the dog at this stage. If the dog is relaxed, the person can toss a food treat in the dog’s general direction. The goal is to teach the dog to associate visitors with pleasant experiences.
Once the dog remains relaxed in the visitors’ presence and is accepting food treats from them, he may be allowed to interact, secured by means of a 10-foot long nylon training leash. The dog should be the one to initiate all interactions with the visitors, not the other way round. If he chooses to approach a guest, have the person quietly offer their hand for the dog to sniff and/or passively hold out a food treat. Never advance your hand rapidly toward the dog’s muzzle.
If the dog indicates that he would like to be petted, the visitor may do so, briefly, but should avoid reaching up and over the dog’s head and should avoid prolonged eye contact.
These exercises should be repeated with a variety of mildly fear-promoting volunteers. The volunteers should engage in progressively more ambitious interactions with the dog.
Whenever a dog is behaving in a fearful manner he should be ignored. Both chastising words and reassurance reward the dog’s unwanted behavior with the owner’s attention. Punishment has the potential to increase the dog’s fear and worsen the situation.
P.S. The use of a head halter, such as Gentle Leader®, makes control of fear aggressive dogs a “cinch.” When fear aggressive dogs are well controlled around strangers, it is then a simple matter to arrange for the correct learning experiences: Basically, that good things happen when strangers are around.