tails held high indicate confidence, self-assertion, or excitement from interest or aggression, while low-hanging tails indicate depression, stress, or anxiety. An erect tail also exposes the anal region, allowing a bold dog to air his odor signature. By contrast, a long tail held so low as to curl back between the legs, closing off the rump, is actively submissive and fearful. When a dog is simply waiting around, his tail is relaxed, hanging low, dropped down but not rigid. A tail gently lifted is a sign of mild interest or alertness.
