The movement of a dog's tail is also one of its languages. Although different types of dogs have different tail shapes and sizes, the movements of their tails express roughly the same meaning. Generally, when excited or when the owner is happy, he will shake his head and wag his tail. The tail will not only sway to the left, but also keep spinning; the tail is raised, which means joy; the tail is drooping, which means danger; Indicates fear; wags the tail quickly and horizontally, symbolizing friendliness. The movements of a dog's tail are also related to the owner's tone. If the owner says Bad guy! Bad guy! in a kind voice to him, he will also wag his tail to show pleasure; on the other hand, if his owner says in a stern voice: Good dog! Good dog! unhappy. This means that, for dogs, the voices of people speaking are only sound sources, acoustic signals, not words.

The activity of the dog's tail is also closely related to the sense of smell and special anal glands. The anal glands give each dog its own unique scent. An excited dog will wiggle its tail to spread its scent; a frightened dog will cover up its anal glands and stop emitting odors. The frequency of tail wiggling reflects the dog's health and excitement, and the faster it wiggles. It means the more excited and healthy, the swing is slow, it means that although there is excitement, but the health is not good. For hunting, police and military dogs on duty, their tail wagging is even more profound.