What Does a Dog’s Tail Do When It Is Very Scared?

When a dog feels scared, nervous, or uneasy, it usually shows a dropped tail, holds it against the body, or tucks it between the legs; in such states the tail does not wag or lift.

This is because the tail expresses emotion–when happy, excited, or friendly, dogs wag or raise it, but when afraid, uneasy, or threatened, they tuck the tail to avoid releasing anal secretions that would reveal their emotional state to other dogs.