Raised Hackles, A Sign of Aggression in Dogs?

People often assume that when a dog has raised hackles that it is displaying dominant aggressive behavior. While this may be the case and one should always be respectful of a dog’s show of reactivity, there are multiple reasons for this phenomena taking place. It is good to become more knowledgeable about dog body language so that we may be able to understand the unspoken signals given off by our canine friends.


In fact, dogs are not the only species to show evidence of what is known as piloerection. Birds, rats, cats, and even humans have an involuntary response of the nervous system where a rush of adrenaline makes the muscles contract causing the hair to stand upright. Have you ever had goose bumps or felt the hair go up on the back of your neck or heard an experience referred to as “hair raising”?


This physical response may be triggered by feelings of fear, aggression, arousal, lack of confidence, anxiety, defensiveness, being startled, or even plain excitement! Hunting dogs have been known to exhibit piloerection when focused with intensity while pointing a bird. Interestingly, the hair raising usually becomes noticeable approximately thirty seconds after exposure to the trigger while taking two minutes to relax.


On a dog you can see the raised hair across the shoulders in a broad swathe. Occasionally you may observe hackles up over the shoulders as well as on the lower back just above the tail. Sometimes you notice a stripe going all the way down the back. Piloerection is more obvious on dogs wit short, stiff coats whereas long, fluffy hair makes it more difficult to spot. Poodles and poodle type coats make it harder to differentiate alsohackles raised as a sign of dog aggression


There is not an abundance of data and there can be discrepancies, but it is believed that the dogs who have hackles raised predominantly over the shoulders or withers have a low level of confidence and have fear or even terror. If extreme, they could strike out if cornered or pushed over their threshold.


If the raised hair forms a line all the way down the back and tail, the dog may be more confident in going on the offense in acting out overt aggression.


The third pattern might be the dog who has hackles raised at the shoulders and above tail, but smooth down the center of the back. This dog is thought to be in a conflicted emotional state, thus having the ability to be reactive and unpredictable.


As fascinating as it is to observe piloerection and determine a possible cause, it is more valuable to assess all of the dog’s body language to determine what is going on with the emotional state at hand and how to best deal with it. In my work with dogs, the majority of the potentially aggressive are reacting out of fear. One must be careful as a bite driven by fear can be dangerous, make no mistake! The difference is in how you analyze the problem and design your approach in helping the dog and owner.

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6 Responses so far.

  1. Laura Helmer says:

    My dog raises his hackles around certain people. I live in an apartment so there is a lot of turnover in residents. Some new people he will go straight up to tail wagging and kisses galore. Other new people, the hackles go up, he starts barking at them and I have to pull him to me. This sometimes happens when meeting new people back to back. Meets 1 person and he’s fine 5 seconds later another person comes by and he goes all Cujo. Time doesn’t usually make him like them any better. Any thoughts?

    • Jessica says:

      My dog does the same exact thing. I would be interested to find out why. I know we didn’t socialize her as much as our other dog, but she is very timid around men and only some new people.

    • Julie says:

      My pit/german is the same way. She is 6 months now. She A such A loving dog. I also live in A APT and she the same way lovee everyone but so far two people her hairs was standing up growing braking and backing up. I’m like oh wow I never seen her like this. She gets happy ane kisses everyone elese.

  2. Christie says:

    Maybe dogs are just better judges of character then we are and that is why they are behaving that way towards some people and not others.
    I have a 3 month old lab mix that will raise the hair all the way down her back when she and my 9 year old Shih Tzu/Poodle are “playing”. Hopefully, she is just being young and testing out her abilities as a dog and testing her limits.
    She has not raised her hair at any person yet, though.

  3. Going through the same thing bought a rescue dog two weeks ago he is 12 years old and fantastic couldnt get better but have noticed now hes showing aggression towards bigger dogs the teeth arent out just hackles up and barking lunging towards them i dont know what to do about it as i dont know his background help…

  4. RobinRG says:

    Our Boxer mix had a ridge of hair standing up from her neck all the way to her tail when she saw a Mylar balloon bobbing in the breeze today, lol. She’s a rescue, and we never know what will cause strong reactions in her. This was the first time I’d seen her hair do that!

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