Why Do Dogs Wag Their Tails?

3904 Why Do Dogs Wag Their Tails?
How a dog holds its tail can tell you a lot about how it feels. Ross Stevenson/Shutterstock.

When a dog wags its tail, it’s telling you a lot more than you might think. Not merely a way to express to you that it’s pleased to see you, the way your pooch swishes its tail could be communicating something far more subtle.

Firstly, the position in which a dog holds its tail says quite a lot. If the tail is held high and tense, it’s a sign that the dog is excited, whereas if it’s lowered and tucked between its legs, then the poor creature is obviously scared. But it’s a little more complicated than even that, as Louise Taylor, a canine welfare trainer at Battersea Dogs & Cats Home, London, explained to IFLScience.


“It’s very dependent on what breed the dog is,” says Taylor. “So for some dogs – for example huskies – their tails come up and over their backs when they’re relaxed, so they’re curved over their backs into a little coil almost. And that’s a happy, relaxed husky. But if a Labrador did that, for example, that would be their highly aroused state.”

And then we come to the actual wagging. “Dogs wag their tails for a number of different reasons,” explains Taylor. “So, it can be when they’re happy, when they’re aroused, when they’re a bit worried.” But you shouldn’t just be looking at the wagging of the tail. Context is everything. “When you’re looking at a dog’s body language, you should never just look at one part of it, you should look at the dog as a whole, to work out what they’re trying to convey.”

Even then, a wagging tail doesn’t always necessarily mean a happy dog. For example, if the wag is slow and cautious, it could mean that the pooch is unsure. It depends entirely on what the rest of the body of the animal is doing. But that’s not all. If you watch a dog really carefully, you might just notice that it wags its tail more to on side than the other. It turns out that this could be telling you quite a bit.

While looking at the asymmetry of the brain, and how different hemispheres control different sides of the body, researchers decided to look into an organ located in the middle of the body, an organ that might be expected to be controlled by both sides of the brain simultaneously. They settled on the dog’s tail, and what they found surprised even them.


Intriguingly, they found that dogs tend to wag their tails more frequently on either the left- or right-hand side of their bodies depending on their moods. If the tail is wagging predominantly to the right, the scientists claim, then the dog is more likely to be happy, whereas if there is a left-side bias the dog is nervous. While these minute differences in how a dog swishes its tail might be missed by us, further research showed that other dogs are fairly well tuned to pick up on these changes.

So it turns out that how a dog holds its tail, and what it does with it, can give you a surprising insight into how it's feeling.

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  • dogs,

  • animal behavior,

  • tails