I can speak very highly of the thundershirt. My one dog is a rescue, former bait dog, and gets crazy when anyone outside of my immediate family walks through the door. She would jump at people, nip at then, bark like crazy, pee on the floor... We used to have to put her in our basement when guests were over.
We started using the thundershirt after our vet used one at his office to keep her calm during an examination. She still gets visibly anxious when new people come over, but she is very calm about it when she has the shirt on... no jumping, no peeing, no nipping. Now we hear little soft moaning when people come in, but that's it.