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How to Tell a Dog’s Emotions by Their Tail

Here are some tell-tail signs that your dog is feeling awesome.

by Julia Lane, CPDT-KA
Updated July 1, 2014
Woman looks down at australian shepherd dog while smiling
Pexels/Alana Sousa

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Need help figuring out your dog’s mood? Well, the next time your dog greets you when you come home, closely watch their tail. What a dog’s tail does speaks volumes, whether it’s rigid or swishing circularly, or if the dog’s tail is moving slowly or quickly. Tail wags are far more complicated than you might think. Now, add one more mood indicator to the list: the position and direction of a dog’s tail while it wags. Scientists have discovered that a happy dog will wag harder to the right, and an anxious dog will wag harder to the left.

Left and Right Brain

In humans, it’s well documented that the brain is divided into two cerebral hemispheres—left and right—which serve different functions and control opposite sides of the body. Most animals also demonstrate a difference between “left brain” and “right brain” functions. It is believed that the left brain in animals specializes in “approach and energy enrichment,” such as finding food. The right brain specializes in “withdrawal and energy expenditure,” such as fleeing in response to fear. Because the dog’s tail is located along the body’s midline, researchers questioned whether or not the tail displayed emotional asymmetry.

Thirty mixed-breed dogs, family pets, served as the researchers’ subjects. Each dog was put in a kennel specially fitted with cameras to capture the precise angle of the dog’s tail movement. The dog was then shown four separate stimuli—their person, a stranger, a friendly cat, and an unfamiliar, intimidating dog—for one minute each.

Upon sight of their person, all thirty dogs wagged their tails more strongly to the right side. After a 90-second rest period, the dogs viewed a stranger. The dogs’ tails still favored the right side, but the angle was more moderate in comparison to seeing their person. The cat elicited a bias to the right side, but it was even more subtle than when they saw the stranger. The large, unknown dog caused all of the dogs to wag their tails more to the left.

Dog Tail Position Meaning

The authors concluded that when the dog felt positive, or curious (as in the case of the cat), the tail wagged right. If the dog felt negative or apprehensive, the tail wagged left. Since the left brain controls the right side of the body, the right muscles of the tail expressed those good feelings—the left muscles of the tail signal caution or concern, which is controlled by the right brain.

  • When a dog’s tail wag position is to the right, it is associated with positive and/or curious tendencies.

  • When a dog’s tail wag position is to the left, it is associated with more negative and/or apprehensive feelings.

It’s always a good idea to observe your dog’s body language, whether you’re relaxing at the dog park or waiting to see the vet. Now, thanks to your dog’s tail, you have another way to tell how they really feel.

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Julia Lane, CPDT-KA

Julia Lane owns Spot On K9 Sports, a training facility in the Chicago area, and offers online dog-sport coaching. She is the author of several travel books, and her byline has appeared in The New York Times Magazine, Poets & Writers and elsewhere.