Whether we realize it or not, a dog’s energetic tail is one key reason we adore the species so much. It’s not just the joyous greeting we receive when we walk through the door (oh, that feeling of unconditional love!), but the enthusiastic flapping of the furry flag at the end of our dogs’ butts. Seems a bit strange to put it that way, but try and tell me I’m wrong!
There’s something endlessly charming about a dog’s tail. It seems to have a mind of its own, yet we know a tail is also at the mercy of its master. Our dog Mabel will slap hers on the floor like an insistent whip if we haven’t taken her to the park in a day or two. Conversely, her tail goes totally quiet during a scolding.
At a high level, dogs wag their tails:
- For balance
- For social reasons
- For communication
- On instinct
But what about the details? Do different wags have different meanings? The answers are curious and fascinating, and we’ve put together a quick tour through the science of tails.
Tails Have a Structural Function
The tail originally evolved to help dogs maintain their balance when turning sharp corners. This aided accurate and efficient hunting, which helped the species thrive and survive.
The tail also helps stabilize a dog when he’s swimming or traversing narrow pathways. So, you can think of a dog’s tail as a rudder, shifting slightly to maintain the body’s balance. But dogs can certainly walk and run just fine if they don’t have a tail (as some Corgis, Dobermans, or Boxers do).
Tails Absolutely Have a Social Function
The tail quickly took on a secondary function—communication. Dogs use the eyes, ears, posture, and stance to send messages to one another. You’ll see this any time your dog meets a new friend on the trail. The tail is just another means of communication to help with more complex messaging between pack members.
Puppies, for example, can raise a tail if rowdy play becomes too intense. Or they can lower the tail to express submission. Or wag it slow and low when seeking food or affection. Another interesting fact that proves the social function of tails: Dogs rarely wag their tails when left alone.
A dog’s tail is also a tool for scent messaging. It basically works like a fan to spread the scent produced by a dog’s anal glands. An alpha dog will hold his tail high when running, allowing for more of his scent to spread far and wide to show he’s the master of a given territory.
A frightened dog, on the other hand, will keep his tail tucked to prevent his scent from spreading, allowing him more anonymity.
Different Meanings for Different Wags
Not all wags are equal. A swinging tail doesn’t always translate to a happy dog, and it’s important to look for other clues to size up a dog’s demeanor, especially when meeting a dog for the first time. Misreading a dog’s entire set of body cues sometimes leads to surprising growls or bites, particularly in interactions with children, who are less skilled at picking up nuance.
A tail can express everything from happiness, joy, and excitement (when wagging high and wide) to worry or insecurity (when wagging low).
Scientists have found that a wag on the left side of the body can mean a dog is scared and ready to flee, while a wag on the right side of the body shows confidence, positivity, and curiosity. This happens because different halves of the brain take over in different contexts, and each half of the brain controls the opposite side of the body.
What About a Dog with Little to No Tail?
Are dogs without tails at a disadvantage? Not necessarily, but a shorter or nonexistent tail can make it more difficult for other dogs to interpret signals. This may put short-tailed dogs at a slight disadvantage when they’re in unfamiliar social territory. But dogs have several methods of communication at their disposal, and can find other ways to get their message across.
As for the question of intent, most researchers think dogs can control their tails if they want to, but they often wag reflexively and intuitively.
Once a dog is socialized, she begins to react emotionally according to the patterns she’s learned, just as humans learn to laugh when we’re entertained. We can do it consciously, but yes—sometimes the tail wags the dog!