Why Do Dogs Wag Their Tails? 4 Reasons You Need To Know

A dog uses her tail for balance: when walking on narrow pathways, steering while swimming, making turns when running, and any other time she needs that type of balance only her tail can provide.

Dogs also use their tails to spread their natural scent, which is released from their anal glands. A dog confidently holding his tail high releases more of his scent than dogs holding their tails lower, while dogs that are afraid hold their tails low to cover their scent so they’re not as noticeable.

Another important use of a dog’s tail is communication, which can be expressed through different signals of tail movement. Dogs also need their tails to communicate. We speak, we smile, we use body language to let others know how we feel. Dogs use their ears, their eyes, their body positions, and their “voices,” but nothing is as important as their tails in communication!

Speculating on whether dog tail wagging is involuntary or voluntary, Dr. Lisa Radosta, Doctor of Veterinary Medicine (DVM) and owner of Florida Veterinary Behavior Service, tells Animal Planet that "we can’t talk to dogs, so we don’t know if they think about the tail wag and then do it, or if it just occurs due to the neurochemical effects of a certain state of mind." She also points out that we can certainly observe dogs in a dog park and see that dogs have one intent or another when they hold or wag their tails in certain ways.

Dr. Stephen Zawistowski of the American Society for the Prevention of Cruelty to Animals (ASPCA), tells Animal Planet that a dog’s tail wagging is similar to a person’s smile. Just like sometimes we smile without knowing it and other times we deliberately smile, dogs do the same with their tails, sometimes unintentionally and sometimes on purpose.

In a 2013 study involving symmetry of the brain, scientists discovered that just as the left and right sides of the human brain control different abilities and areas of human behavior, so it is with dogs. A dog’s right side is controlled by the left hemisphere of his brain, and his left side is controlled by the right brain hemisphere. The simplest way to remember the importance of this is that the dog’s tail wagging to his right! indicates positive, happy emotions. When his tail wags to the left, this indicates negative, leave-me-alone emotions. While we as humans don’t always notice or understand these differences, the study shows that dogs do understand and respond to this communication by either immediately becoming more relaxed or stressed, depending on the communication received.

This is an important piece of information to know, although if we pay attention to dogs when they meet each other, we probably know this already. They watch each other’s faces, body stance, tail position, and tail movement, which makes a lot of sense when you think about it. While we’re busily catching up with the other dog owner, the two pooches size each other up and start their own communication. Paying attention to body language is as vital to a dog’s communication as listening, talking, and being aware of body signals is to us.

As we can see, a dog’s tail is vitally important to her life for many reasons. The most obvious and important reason why a dog wags their tail is for communication purposes. Social life is important for a dog as well as for humans. To socialize, we all need to communicate!

Let’s get more specific about the particular ways dogs wag their tails and their unique signs and meanings.

If a dog’s tail is held high, this means she is confident and engaged in the situation. However, that doesn’t tell us if she’s confident because she loves you or because she knows she is going to win in this battle! The tail held high means that the dog is very confident and ready to interact, but not necessarily in a positive way. If you can’t tell which, you need to leave this dog alone. If she is your dog, you will want to calm her down and get her out of the situation.

If the dog wags her tail to the right, she is feeling happy and positive. The full body wag, where the whole behind of the dog is moving and the tail is sweeping from side to side, usually means what most of us think it does: that the dog is very happy and friendly!

If the tail wags to the left, she is frightened or wants to leave the situation. Dr. Karen London, Certified Applied Animal Behaviorist and Certified Pet Dog Trainer in Flagstaff, Arizona, tells PetMD that tail stiffness may also be significant. “Generally, a loose, flowing wag is good, but a stiff wag can communicate tension or hostility.” Tail wag speed can also be an indication of this. Dr. London notes that a slow wagging tail may mean that a dog will not be friendly, while a fast wagging tail usually is a good thing. Some breeds, however, may just naturally wag their tails slower or faster, or higher or lower than another.

If a dog learns that a certain body signal, such as tucking her tail, keeps her safe in a threatening situation, Dr. Radosta tells Animal Planet that she will likely use this signal again. “The changes in tail wag and tail carriage depend on the stimulus and can occur very quickly…. Any veterinary technician who has tried to take a dog’s temperature rectally will tell you that the tail can be tucked quickly to avoid a rectal thermometer,” she says.

It is important to know your own dog and what is normal for him as well as for his breed. With my little Yorkie, I need to learn his body language and pay attention to his tail in different situations so that I can know right away when something is amiss.

If you have learned any valuable or helpful information from this article about taking care of your dog, please SHARE it with others who may benefit from learning about their dog’s tail wagging signs.