"As crazy as this sounds, recent research indicates that a dog wagging his tail more to the right is more relaxed than a dog that is left-wagging."
©Scott Sheaffer, CDBC, CPDT-KA, USA Dog Behavior, LLC
Dogs provide information about their emotional state through their tails. While happy dogs may wag their tails, sometimes wagging can mean something else.
A wagging tail generally indicates happiness with the exception of flagging. Flagging occurs when a dog holds his tail stiff and high while slowly and rigidly moving it back and forth - this can be indicative of potential aggressive behaviors toward a human or another animal. This is the classic, "But he was wagging his tail before he bit me" scenario.
Here is a good rule of thumb: If a dog's body is stiff and his tail is rigid (whether wagging or not), it might be a good idea to steer clear until he relaxes a bit.
Most dogs hold their tails from about a 12:00 position to about an 8:00 position when viewed from the side. Think of a dog’s tail as an analog dial with the following values along a continuum:
12:00 - highly aroused
3:00 - moderately aroused
6:00 - relaxed
8:00 - anxious
As crazy as this sounds, recent research indicates that a dog wagging his tail more to the right is more relaxed than a dog that is left-wagging. See the video below to view this left-right bias.
Not all dogs have the ability to communicate effectively through their tails. Dogs that have docked tails (e.g., Doberman Pinscher), naturally short tails (e.g., Australian Shepherd) or curled up tails (e.g., Pug) can lose some or all of their ability to communicate with other dogs through their tails. This can sometimes cause conflict between dogs because of misunderstandings.
It is important to remember that dogs' tails are only one consideration in reading their body language. When I’m working with dogs, especially ones that I’m not familiar with, I also carefully watch their eyes, ears, body stiffness and mouth.
What does a happy and relaxed dog look like?
Slightly flexed front legs
Open and relaxed mouth with a still tongue
Squinty or almond shaped eyes
Ears somewhat back
Relaxed and wagging tail
Rear-end that is wiggling back and forth with the tail
The combination of the above things is usually a good predictor that you are dealing with a happy, confident and relaxed dog.