Have you ever seen a dog with “raised-hackles”? I bet you have. The technical term is piloerection and it means just that – the hair standing up.

What you probably don’t know is that piloerection is NOT aggression, as many folks believe. It is actually arousal. The best way for me to describe arousal is to say that arousal is an autonomic response from the nervous system. In other words, it is not a voluntary response that the dog can turn on and off at will.

Whenever we see a dog exhibiting piloerection we should pay attention because it could just mean that the dog is very excited over something; such as seeing a person or a favorite pal. But also, piloerection – or best said – arousal can also be a precedent to an escalation of aggression.

So how is one to know? It all depends on the context. It is never advisable to just focus on one visual element of dog body language because most likely this will not give enough information to make a good assessment of the situation. So if we pay attention to the dog’s overall body language, and this could be done in a matter of seconds, we will be more successful in anticipating the motivation behind the piloerection.

This is a good illustration as to how piloerection can “mean” different things: My two female dogs Laika and Rio display piloerection often. Laika would almost exclusively when she was ready to interact with a dog she consider “soft”. Dogs that she wanted to intimidate just for fun.


Ahh, and Laika was a very “nice” dog with great dog skills who also enjoyed bullying them on occasion until I said no more! Laika was a very confident dog.

In the case of Rio, our current female pup, she exhibits piloerection daily. If she spots someone in our driveway her howling and barking will always be accompanied by piloerection. She will do the same even when the person in our driveway is John coming in back from out of town. Rio also does other things when she is in situations that she finds a bit overwhelming such as saying hello to someone.

She will bark, howl, have piloerection AND turn around looking to see if Deuce is in the vicinity and following her because she lacks the confidence to interact. So here arousal is a bit more a case of the “jitters” – to use a “very” technical term. 🙂

The learning I wish folks would take from this is that piloerection is an easy identifiable visual cue that we must pay attention to and to remember that is not aggression, but it could be an antecedent to aggression. Physiologically and evolutionarily speaking, pilorection also functions to make the animal look bigger to a potential threat. But as you can see by my examples above, there might be different motivations for this.

Back to Rio and her arousal. I can almost bet with great certainty that if Rio found herself in a situation where she felt somewhat threatened, her first line of defense would be to retrieve. Now Laika, for example, I am not sure she would. Same response from the nervous system, but a different outcome.

When I see either my dogs or a dog that I know well have pilorection, one of the things that I like to do is to gently press the back of my hand down their spinal cord beginning at top of the neck and down to the tail. Literally “combing” down the standing hair. Over and over again, the reaction that I have seen is the dog returning back to equanimity. Our dogs cannot “control” pilorection, just like a person that has road rage cannot control feeling the emotion. However, what our dogs and the road-rage laden individual can learn is how to respond when they are going “through the motions”. And this is where it gets very interesting! Enter the world of learning….