Learn to Speak Dog: A Must-Know Guide for Animal Lovers A relaxed posture with a neutral head and tail position shows that the dog is calm and comfortable. A dog in alert mode stands tall with its tail raised, showing full attention and awareness. A defensive stance, with a stiff body, lowered head, and tail, signals fear or feeling threatened. A high tail position reflects confidence and happiness, while a low tail can indicate submission or discomfort. A wagging tail usually means the dog is excited or joyful.