Just a bit of canine trivia:
Retrievers, setters, and other hunting breeds are wiggly, waggy dogs-- waggy all over, in fact, to help them wriggle through dense brush while hunting game. These dogs often have tails that never stop moving!
German Shepherd dogs, Collies, and other herding breeds have what is known as "quiet tails." These are tails that usually wag only when the dog is trying to send a social signal. A "quiet tail" won't alert the stock (sheep, goats, cattle).