Original photo by Ekaterina Naumova/ iStock
Dogs have evolved significantly over time to endear themselves to humans. They use their eyes, ears, mouths, and tails to communicate their emotions; a wagging tail, for instance, is typically thought of as the universal symbol of a happy dog. But the reality is a bit more complex.
While a joyful pup does indeed wag its tail, the speed, position, or even the direction of a tail wag can convey a wide range of emotions. Just like with humans, there are also anatomical differences to keep in mind. Some breeds, such as Beagles or terriers, naturally carry their tails high, while Greyhound and Whippet tails are naturally low, so interpreting a dog’s tail signals also means keeping their normal tail position in mind. Here, we decode the secret language of a dog’s wagging tail.
The Full-Body Wag: Excitement
Few things evoke simple joy as much as a dog wagging its tail so fast and so broadly that its whole body wiggles. This type of enthusiastic wag — often paired with squinted eyes, relaxed posture, and a happy, open-mouthed expression — signals pure excitement. It’s a greeting many dog owners know from coming home after being away or when playing with their beloved pup.
Tail wagging isn’t something dogs are born able to do; puppies typically start wagging their tails sometime between 3 weeks and 7 weeks old. Wolves, dogs’ wild ancestors, rarely wag their tails, illustrating how domestication has played a role in shaping many communicative behaviors of tamed canines.
Slow and Low: Uncertainty
Not all tail wags are signs of happiness. When a dog wags its tail slowly, especially with the tail held lower than usual — half-mast or lower — it may be feeling uncertain or hesitant. This kind of wag is often seen in dogs who are assessing a new situation, perhaps encountering a stranger or sniffing out another dog or a new toy.
As with any type of tail wag, it’s important to pay attention to the overall body language. A hesitant tail wag, for instance, is often accompanied by a lowered head or a slightly tensed posture. Though you may be tempted to offer reassurance, it’s better to give dogs some space while they sort through those feelings of incertitude on their own.
High and Stiff: Alertness, Dominance, or Aggression
A tail held high with a firm, deliberate wag most likely isn’t a friendly gesture. In most cases, it signals alertness or dominance. According to canine behavior expert Stanley Coren, if the tail is held high while tightly wagging or vibrating, it may even signal an active threat.
This could indicate a dog is ready to fight or possibly run. If the tail suddenly stops wagging, it could mean the pup is attempting to avert a threat without becoming aggressive — but it could also signal it’s about to pounce. In interactions between dogs, a high, stiff wag can also be a way of asserting superior social rank.
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Wagging to the Right: Positive Emotions
Dogs don’t just wag their tails — they often wag them asymmetrically, and the specific angle can mean different things. Studies have shown the direction of a tail wag is linked to brain hemisphere activity similar to right- or left-brain dominance in humans.
Neuroscientist Giorgio Vallortigara found dogs tend to wag their tails more vigorously to the right (from the dog’s perspective) when experiencing positive emotions, such as seeing their owner or anticipating a treat. This is linked to left-brain activity, which controls the right side of the body and is associated with feelings of calmness and approach-oriented behaviors including interaction, exploration, and engagement.
Wagging to the Left: Stress or Anxiety
Just as a right-leaning wag can signal positive emotions, a tail leaning more to the left can indicate stress or anxiety. Vallortigara’s study found that when dogs saw something intimidating, such as an aggressive, unfamiliar dog, their tails wagged toward the left side of their body. This checks out, as the brain’s right hemisphere controls the left side of the body and is associated with processing “withdrawal” feelings of fear, sadness, and heightened alertness.
Interestingly, Vallortigara’s team also found that dogs respond to the direction another dog’s tail is wagging, becoming more relaxed when they see a rightward wag and more anxious when they see a leftward one.
A Tucked-In Tail Wag: Submission or Nervousness
A wagging tail doesn’t always signal confidence, either. When a dog wags its tail while keeping it very low, it’s a sign of submission. If the dog goes so far as to tuck the tail between its legs, especially if a small, tentative wag persists, it indicates the dog is feeling overwhelmed.
This often happens when a dog is feeling fearful and trying to diffuse any potential conflict, which explains why we use the saying “with one’s tail between one’s legs” to express similar feelings of vulnerability in humans.
Nicole is a writer, thrift store lover, and group-chat meme spammer based in Ontario, Canada.
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