My mother once had a similar problem with a neighbor's dog. Her "back" door was actually on the side of the house. It faced a similar door on the neighbor's house about 8 feet away. There was only a wire fence about 3 feet high separating the two yards. The dog, a German shepherd, would bark ferociously at my mother every time she went out her door. From only a few inches away!

Finally someone gave her some advice that worked. Just before exiting the door, they said, make some kind of noise—it doesn't have to be especially loud or frightening to a human, but it has to be mysterious to the dog. You have to make sure it's a kind of sound he's not familiar with, so he won't have a clue what kind of thing is making it. And you have to make sure he doesn't see how you make it. (I'm sure you musicians can come up with some ideas.)

My mother hung an old wire barbecue grille on the inside of the back door, and every time she was ready to leave by that door, she would open it a few inches (this always attracted the dog's attention), and then, before stepping out, she would rake her keys across the grille. It worked! The dog was so spooked that he shut up and backed away from the fence. It not only worked once, but the same sound worked over and over! And eventually she was able to quit making the sound altogether and the dog kept quiet.