A dog wagging its tail is not necessarily happy. The meaning is in which direction the dog wags its tail.
Wagging a dog’s tail is a gesture that everyone knows. Many people interpret a dog wagging its tail as being happy, although this is not necessarily the case.
Some dog owners can, for example, continue the violent wrestling game even when the dog is already wagging its tail and begging for mercy.
In addition to happy tail wagging, there is nervous tail wagging.
This is what a doctor of animal behavior science and non-fiction writer writes Helena Telkänranta What is it like to be a dog? in the book (SKS Kirjat 2023).
The book says that you can distinguish happy waving from worried waving first of all by looking at the rest of the dog’s body.
A happy dog’s posture leans forward hopefully, while a worried dog’s body hunches a little. The eyes are larger and rounder than usual.
A worried dog’s tail wags a little lower and faster than a happy dog. There are big differences in the speed and height of tail wagging between different dogs, so the wagging speed must be compared with the same dog in different situations.
Tail left or right?
A universal sign of a dog’s mental state is asymmetry in tail movement. In a happy dog, more than half of the tail movement usually takes place on the right side of the midline of the back, seen from the dog’s own perspective, Telkänranta says in the book.
A worried dog’s tail goes more to the left.
The half differences are due to the division of labor in the brain. Rewarding things are processed in dogs’ brains mostly in the left hemisphere, threats in the right.
Nerve tracks from both hemispheres of the brain go to different parts of the body, and the nerves going to the tail cross along the way. When the right hemisphere is more active, the tail wags with an emphasis on the left and vice versa.
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Dogs recognize sign language
Dogs also recognize other dogs’ emotional states by following their tails.
In studies, dogs have been shown computer-processed videos in which the facial expressions and gestures of the visible dog remain the same, but the tail wags either on the right or on the left side.
Studies have shown that the viewer’s dog’s own expressions become worried and the heart rate increases when the dog wags its tail on the left side in the video.
Dogs learn to read this nuance of sign language if they spend time with other dogs while holding a puppy.
According to Telkänranta, wagging the tail is a basic signal for a dog that goes by itself. On the other hand, understanding signals requires opportunities to learn from other dogs.
The story was originally published on February 6, 2023.