The Hidden Meaning in a Dog's Wagging Tail
Little known fact: When a dog is alone, it will hardly wag its tail. Indeed, it may not even wag its tail at all. The appendage isn't some autonomous, unifunctional machine that never quits; it's actually a complex communication device. So, when there aren't any other living things around, there's little point in wagging it.
"In some ways, tail wagging serves the same communication functions as a human smile, a polite greeting or a nod of recognition," writes Stanley Coren, a professor of psychology at the University of British Columbia and an expert in dog intelligence. "Smiles are social signals and are thus reserved mostly for situations where somebody is around to see them. For dogs, the wag seems to have the same properties."
Tailing wagging in general is commonly thought to indicate that a dog is happy. It certainly can imply contentment, but anxiety, insecurity, excitement, curiosity, and submissiveness are other emotions also in a tail's repertoire of expression. Lucky for humans -- though -- happiness is easy to pinpoint.
"The more the wag spreads to the body, the happier I assume the dog to be," writes Patricia McConnell, an animal behaviorist and a professor at the University of Wisconsin-Madison. "I call it a 'Full Body Wag,' in which the tail, the hindquarters and sometimes even the chest of the dog swings back and forth."
Tail wags that communicate other emotions aren't nearly so flamboyant. A study published in 2007 found that dogs tend to wag their tails more to the right when they see something they're curious about and want to approach, and more to the left when confronted with something they want to back away from, an intimidating animal, for example. In 2013, the same research group published another study corroborating those results. They found that when other dogs viewed tails wagging to the right, they were more relaxed. But when they saw tails wagging to the left, their heart rates increased and they showed signs of stress and anxiety.
Those directional inclinations are slight, however, and can be difficult to spot. Other tail signals are easier to interpret. According to Coren:
The tail's position-specifically, the height at which it is held-can be considered a sort of emotional meter. A middle height suggests the dog is relaxed. If the tail is held horizontally, the dog is attentive and alert. As the tail position moves further up, it is a sign the dog is becoming more threatening, with a vertical tail being a clearly dominant signal meaning, "I'm boss around here," or even a warning, "Back off or suffer the consequences."
As the tail position drops lower, it is a sign the dog is becoming more submissive, is worried or feels poorly. The extreme expression is the tail tucked under the body, which is a sign of fear, meaning, "Please don't hurt me."
In terms of communication, we humans are truly oddities. Our heavy reliance on complex sounds in the form of language sets us apart in the animal kingdom. Thus, it makes sense to read your dog's body language and heed your own. Doing so will undoubtedly lead to a more enriching relationship with your "best friend."
(Sorry, cat lovers, science has yet to study the swaying of your pet's tail.)