Almost all of us have heard that a dog wagging its tail is happy. That is only half true. Wagging the tail is primarily a sign that the dog is aroused and ready to interact, and this arousal can mean joy, nervousness, or tension. To know which one it is, you have to look at how it is wagging it and at the rest of its body.
Tail height
Each breed has its natural position. A greyhound's is not the same as a husky's or a pug's, so the reference point is your own dog's tail when it is calm.
- At the usual height or slightly below: relaxed state.
- Higher than normal: alert, interested, or confident. If it is also stiff, there may be tension.
- Low or between the legs: fear, insecurity, or discomfort. This is a dog that needs space.
Speed and amplitude
The type of movement says as much as the position.
- Wide, loose movement, sometimes in a circle, with the hips moving as well: friendly greeting. This is typical of when you arrive home.
- Short, fast movement with the tail held high and stiff: intense excitement or tension. It is not an invitation to approach, especially if the dog does not know you.
- Slow movement at medium height: hesitation. The dog is assessing the situation.
- Low tail wagging fast: usually seen in dogs that are being submissive or appeasing, for example in front of an older dog.
Does the direction of the wag matter?
There is a curious fact that circulates a lot here, and it is worth explaining correctly. In 2007, a team at the University of Bari (Italy) observed that dogs tended to wag their tails a little more to their right when seeing their owner and more to their left in front of an unfamiliar dog that they found imposing. In 2013, the same group saw that other dogs became somewhat more nervous (with higher heart rates) when watching a video of a dog wagging its tail to the left.
The idea is that each hemisphere of the brain relates to different emotions. These are small studies and the difference is subtle, measured with cameras. To the naked eye, it is not a reliable clue for knowing how a dog is feeling on the street.
What the tail is for, besides communicating
- Balance: helps with sharp turns, jumps, and walking on narrow surfaces.
- Scent: by wagging it, the dog disperses the scent from its anal area, which other dogs read closely. That is why a very high and wagging tail also "announces" the dog.
- Swimming: in some breeds, like the Labrador, it works almost like a rudder.
How to read the whole picture
The tail alone can be misleading. Before approaching a dog, especially if it is not your own, also check these things:
- The body: loose and wavy, or stiff and still?
- The mouth: relaxed and slightly open versus closed and tense, or retracted lips.
- The ears: in their natural position, or pinned back or pulled far forward.
- The eyes: soft gaze versus a fixed stare or with the whites of the eyes visible.
- Calming signals: yawning, licking the snout, or turning the head usually indicate that the dog is uncomfortable.
A dog with its tail wagging, body stiff, and gaze fixed is not happy. A dog with a loose body, relaxed mouth, and a tail sweeping the floor almost certainly is.
Short tails and docked tails
Some dogs have very short tails by nature, and others have them docked. In Spain, Animal Welfare Law 7/2023 prohibits mutilations for aesthetic purposes, including tail docking, except for veterinary reasons. A dog without a tail still communicates, but loses part of its "vocabulary," and other dogs may misunderstand it. With them, it is advisable to pay even closer attention to their posture and face.
Understanding these signals makes walks and training much easier. In our dog training section, you can find treat pouches and fanny packs, whistles, and accessories for positive reinforcement training.