Why Do Dogs Wag Their Tails?

A Waggy Tail

Most people associate the wagging of a dog’s tail with friendliness. While this may be the case, there are many other reasons why our furry friends wag their tails. 

Naturally, dogs wag their tail when ready to interact. However, it’s not all the time that the interaction is positive. Sometimes it’s negative. Therefore, when you see a dog wag their tail, don’t assume it’s friendly.

Read on to learn several emotions dogs convey by wagging their tail.

Anatomy Of A Dog’s Tail

A dog’s tail is the end of his spinal column. It is attached to the backbone, though attached isn’t exactly the right word. In fact, a dog’s tail is the hindmost end of his backbone. 

It consists of six to 23 vertebrae enclosed by muscles that are attached to the vertebrae by tendons. The highly mobile and flexible vertebrae and muscles give the dog an enormous amount of control over how his tail moves. He can lift it, move it from side to side or pull it down to cover his anus and tuck it between his legs. 

In every one of these positions, the tail is capable of many different movements, making it nearly as expressive of emotions as a human’s face.

Why Do Dogs Wag Their Tails?

Dogs primarily wag their tails as a way of communicating their emotions.

Dogs are not born knowing how to wag their tails, but most puppies learn how to use their tails to communicate by the time they’re about a month old. 

As they grow, they learn an entire “language” of tail gestures. Some of these seem instinctive and some serve more purpose than simply communicating with others. 

These are a few of the hints you can use to determine what your dog’s wagging tail is telling you.


If your pet’s tail is in a slightly upright or neutral position and wagging at a not-so-fast speed, it’s an indication your dog is happy or friendly. 

At such a time, the tail is usually more relaxed than usual. Additionally, it appears to be wagging stress-free with a lot of freedom. Sometimes you’ll notice a “helicopter tail” or “circle wag.” Such wagging is round or circular in motion.

Scientists also say an excited dog may also wag its tail to the right. According to the research, the brain’s left hemisphere controls the dog’s right side of the body. And because this is the part associated with positive emotions, then your dog may be expressing happiness.

On the other hand, left-sided wagging may indicate an anxious or stressed dog. Such dogs tend to exhibit tendencies of withdrawal.


A submissive dog will tend to move their tail down instead of up. The tail will remain between their legs. This is a sign of submissive fear. It happens after your pet senses a threat but backs down out of fear of getting harmed. 

Sometimes the dog will slightly wag their tail while in that position. It’s a sign of submission, and your dog may be frightened.


Canine aggression is of different types, including fear, territorial, and leash aggression. Nevertheless, when your dog gets aggressive, they’ll present the same signs. 

The dog will move its tail up so that it’s in a vertical position arching over its back. Sometimes, the tail is very stiff. If the dog starts wagging with the tail in that position, know that your canine friend is ready to attack or fight.

The faster the wagging, the more aggressive and agitated they are. 


A curious dog will have its tail standing horizontally. This happens when it’s curious about something in the surroundings, such as an unfamiliar smell. 

When out with your dog in new sights, you’re likely to observe its tail in that position. At the same time, the dog may perk up their ears while standing alert.


As mentioned earlier, an alert dog stands and raises its ears. At the same time, they may move the tail a little.


Besides the role that tails play in communication, a dog’s tail is also important to his balance. 

A long, thin tail helps a dog counterbalance himself when he’s running and has to make a turn, for example. 

Long, bushy tails may also help a dog keep warm. Many dogs will pull their furry tails over their faces when they lie down in cold weather to keep their heads and ears warm.

Do Dogs Only Wag Their Tails When They’re Happy?

A common misconception among many is that dogs only wag their tails when happy. However, this is not true.

You see, just like humans use their eyes and hands to communicate, dogs use their tails as physical communicators. That doesn’t mean they don’t use other parts of their body to communicate as well.

By paying attention to a dog’s tail, you can tell what they’re feeling. If happy, a dog will wag the tails in a carefree manner. Such a wag is usually big, and the more vigorous it is, the happier your pooch is. Additionally, your dog may wiggle the whole body, indicating they’re excited and ready to interact and play.

When sad, anxious, and stressed, your dog will still wag their tail, only with less vigor, and as scientists say, towards the left side. Other tail positions, as discussed above, indicate different emotions such as curiosity, alertness, submission, aggression, fear, and avoidance.

Therefore, don’t assume a dog is happy just because they’re wagging their tail. Sometimes, it means the dog is in high moods, and you should play with them. Other times, the dog is stressed and needs your comfort. 

When aggressive, give them space to allow them to calm down. You can then interact with the dog later.

Can You Use a Dog’s Tail Wagging to Tell What Mood They’re In?

A dog’s tail wagging is a communication of its feelings, emotions, and mood too. In fact, no other part of a dog’s body communicates more than the tail. That’s why you need to pay close attention to its position and wagging from time to time to help you know when to play with them, comfort them, or give them space before engaging them.

A tail held high when wagging indicates a happy or enthusiastic mood. It’s a dog open to affection or petting. 

On the other hand, a tail held low shows a nervous dog. If further down between the legs, the dog may be frightened or in a panic. It’s worth noting that when the tail is high and wagging at the tip, it indicates the dog is alert, maybe after sensing a threat.

A dog in a tense mood will make a stiff wag. Sometimes, the tail will remain extremely stiff without moving. If the tail is wagging freely, then the dog is in high spirits. You can approach it for some game time.

The speed of wagging also comes into play when dogs are expressing their mood. A fast wag is a sign of positive feelings. And when it wags slowly, it may indicate a cautious, sad, unsure, or stressed-out dog.

The idea is to observe the tail height, stiffness, direction, and speed. That way, you can tell the mood your four-legged friend is in.

The Bottom Line

Dogs wag their tails to communicate both positive and negative emotions. However, the speed, position, stiffness, and direction change depending on your pet’s mood. Therefore, you can expect different wagging for a happy, curious, submissive, fearful, alert, or aggressive dog.

Granted, you may not learn what your dog is communicating through its tail within a day or two. But you now have an idea of what to observe. Remember, it’s not just a happy dog that will wag its tail, but one in different emotions, feelings, and moods.

By understanding the language of the tail, you can better gauge what your dog, or any other dog, is trying to tell you, and save yourself from potentially dangerous situations.