Whenever there's something your dog dislikes or is afraid of, you can use counter conditioning tactics. Counter conditioning is the act of re-teaching a dog to have a neutral or good association with something that was once disliked or feared. If there’s something your dog dislikes or is afraid of, you can use rewards to help change your dog’s feelings about “the thing” and produce a neutral or good reaction over time. Rewards can be food, a toy or even praise, and you can use these tactics to help your dog feel better about the new person.
Follow these tactics to get started:
(1) Use food or non-food rewards to develop good associations. Whenever the person is around, have them provide your dog with treats, a favorite toy, and have them be the one to feed your dog dinner. Over many repetitions, your dog will associate this person with good things - like food or a toy! Be sure to respect your dog's distance requirements and pay attention to body language during this process.
(2) Don’t reinforce a behavior by attempting to use punishment. With many dogs, any attention from you may seem like a reinforcer. Usually, when reaching into the punishment tool kit, yelling and scolding are the first things you’ll pull out. For a dog who is highly rewarded by words and attention, you might inadvertently reinforce a behavior you don’t like. Taking your attention away from your dog can be a more effective punishment. Try developing a kind of “screensaver” mode —become extremely still and quiet until your dog stops doing the behavior you don’t like. The stark difference between you when you are still and you are when you are normal will make the reward of your attention all the more valuable.
(3) Be patient. Your dog’s response is involuntary at this point. You are working to change it, but until the emotional response has been changed, know it will be hard to get a reliable and consistent behavior response.