Why Do Dogs Wag Their Tails?


Dogs are highly social animals that use a complex combination of body postures, facial expressions, and vocalizations to communicate with one another. Tail signals are an integral part of this canine code.

The History of Tail-Wagging in Dogs

Tail-wagging evolved among ancestral wild dogs as a type of communication system that could be easily spotted from a distance. This technique was enhanced even more by evolution. To increase visibility, some dogs' tails became bushier, some acquired a lighter underside, and others developed a contrasting white or black tip (Stanley Coren Ph.D., 2011).

At close range, tail-wagging might help disperse into the air the distinctive pheromone scents from a dog's anal sacs, located just inside the rectum. These pheromones also communicate important information from dog to dog.

Tail-Wagging Facts

Here are some interesting things to know about dogs and tail-wagging.

What Does a Dog's Tail-Wag Mean?

A relaxed and friendly dog will wag her tail as a cordial greeting that's analogous to a human smile. But a wag of the tail does not always indicate friendliness. It can also signal dominance, aggression, submission, or uncertainty. As is the case with most aspects of canine body language, it's important to read all of the cues together. Tail position, body language, and facial expression all play a part in deciphering what a dog is trying to "say."

Here are some things that the wag of a dog's tail may be trying telling you:

In general, a dog's tail starts out in a neutral, horizontal position. As it gets higher, it means the dog is more excitable, on alert, and potentially aggressive. The lower it dips from neutral, the more unsure, scared, and timid she is. You must evaluate this on a case-by-case basis because some breeds of dog have a neutral tail position that is normally higher or lower than others.

Here are two additional tail-related terms:

Ready for a Really Weird Tail-Wagging Fact?

Researchers have discovered that the direction in which a dog wags her tail differs depending on the trigger for the wag. When a dog sees her owner, an unfamiliar human, or a cat, she wags her tail predominantly to the right (her right, your left when you're facing her) and the vigor with which she wags is greatest for her human.

However, when a dog sees an unfamiliar dog with dominant or aggressive body language, her tail wags more predominantly to the left.

Researchers have determined that this difference in tail-wagging direction has to do with the side of the brain that controls the emotions the dog is feeling when she is exposed to various stimuli. When her tail wags to the right, her left brain, which is associated with positive feelings, is in control. When her tail wags to the left, her right brain, which controls withdrawal and the trigger of the fight or flight response, is in charge (A. Quaranta, 2007).

This research indicates that dogs really do convey their emotions with their tails.

Works Cited

  1. A. Quaranta, M. S. (2007, March 20). Asymmetric tail-wagging responses by dogs to different emotive stimuli. Retrieved from Current Biology.
  2. Stanley Coren Ph.D., F. (2011, Dec. 5). What a Dog's Tail Wags Really Mean: Some New Scientific Data. Retrieved from Psychology Today.

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