Talk about Tail Hackles

Tail hackles on a dog looking at another dog.

After evaluating and working with many bully-type dogs, I started to notice something about their hackle posture, particularly when I was assessing dog-to-dog aggression (or lack thereof). I noticed that some dogs’ tails would hackle about an inch or two up the tail from the base. Some dogs’ tail hackles would raise when they were in front of another dog, or even just sniffing the smell of another dog, usually dog urine.  I started wondering why did some dogs’ tails hackle when other dogs’ tails did not.  Did this have any significant meaning?

Hackling, or more technically called “piloerection” is commonly seen in dogs.  Surprisingly I could not find a lot of research or information about the meaning behind different areas on a dog that may hackle.  Piloerection is something mammals do, including humans.  On humans it is called goosebumps.  But on a dog, it causes the hair to stand up along when the skin puckers. 

Many people misinterpret hackles on the back as a sign of aggression. Roger Abrantes describes hackles as occurring when “the dog is taken by surprise and shows submission” in his book Dog Language An Encyclopedia of Canine Behavior.  Mr. Abrantes states he believes that fearful dogs would raise hackles to appear more intimidating. Patricia McConnell describes piloerection as “an indicator of arousal, not potential aggression” on her website patriciamcconnell.com. “There are a lot of emotional states that can correlate with arousal, including fear, excitement and surprise, and some of those might lead to aggression, but not necessarily.”   I certainly know some dogs like that raise hackles when surprised or aroused that are not aggressive, including my own dog Shiloh.  Shiloh’s hackles go up both on her shoulder area and her lower back when she is barking at a noise or intruder like a crow.

My dog Chardonnay raises her hackles down her back whenever she meets a new dog or new person.  But she is far from aggressive with dogs or people.  With Chardonnay, my guess is that she is aroused because she likes to be in control of a situation, but she is slightly insecure, so this creates conflict within her, hence her hackles raise.  She is also an example of hackles raising all down the shoulders and back when a dog is unsure about other dogs.

Chardonnay with hackles raised down her back

My dog Annie would hardly ever have her hackles raised.  She was a confident dog without fear.  She was very protective and territorial.  If any hair raised on her, it was only on her shoulder area, never down her back.  My dog Tipton gets hackled up in his shoulder and lower back when playing. He is likely over-stimulated or aroused during play, but not aggressive with dogs.

Tipton with hackles up on his shoulders and lower back while playing.

I have seen tail hackles most frequently in bully breed type dogs.  Perhaps the hackles are visible on a bully-type dogs because of their short single coat, making the hackles easily seen on bully breeds as compared to longer or thicker coated dogs.  Once I started to notice this tail hackle phenomenon, I started looking for it on other breeds of dogs. I don’t have an answer as to why this tail hackling seems to appear in only bully-type dogs. I have only seen it on other breeds of dogs twice.  More on that later.

After seeing tail piloerection on many dogs, I started to realize the dogs displaying the piloerection had some level of dog aggression, or at the very least are “overly interested” in dogs and in other dogs’ smells.   I have seen a tail puff up when dogs are sniffing other dogs’ urine or smell other dogs.  I have also seen the tail hackle when a dog sees another dog, and it is often combined with forward, confident posture, not insecurity. It is pretty safe to say that the dogs shown in these photos with tail hackles are not insecure about the other dog or the target of their eye contact.  Knowing the history of many of the bully breeds stems from dog fighting, it is likely that the arousal, when paired with an assertive stance and forward action towards another dog, stems from an aggressive mindset.

NOTE: I want to make it clear that I am NOT proposing every dog with tail hackles is dog aggressive or every dog without tail hackles is dog friendly.  Dogs can be dog aggressive and be perfectly fine with people or “dog selective.” Two of the dogs in the video that goes with this article live with other dogs, but probably couldn’t live with just ANY dog. I think tail hackles is something to take note of.  It can be one piece of the puzzle when assessing a dog.  To apply the possibility of tail hackles meaning aggression, one must tale in all the behavior the dog is showing and pair that with body language to make an assessment.  

The dog in the first photo of this article is super friendly with people, but does not get along with other dogs. She was staring at another dog when the photo was taken.  Her tail was also wagging, which is often misunderstood as friendly, indicating she was aroused.  But she is not insecure around dogs.  She gladly welcomes conflict with them.

Black male dog with hackles up while sensing other dogs existed and looking at another dog.

This black dog’s tail hackles are raised and he wanted to go forward when he smelled, heard, and then saw another bully-type looking dog. 

The red pit bull puppy in the photo with the black dog is intense and targeting the black dog’s neck in what many would see as play.  But she is not playing.  She is practicing fighting and her tail has a large puff about 2 inches above the base.

Red dog has tail hackles raised. This dog is dog aggressive. She is a puppy in this photo.

In the two pictures of the black pit bull and the blonde dog exchanging greetings below, their tails are up, but there are no tail hackles.  (I am always extra careful with pit bulls interacting with other dogs due to potential of dog aggression.). The black dog is a confident, but not pushy dog.

No hackles in this greeting

One dog that was not predominantly bully breed that showed tail hackles was the black dog in the kennel (photo below).  This time, the dog was staring at me, not another dog. This dog was feral and was not afraid of people and confrontational.  It is rare for a feral dog to make direct eye contact while grabbing a leash, chewing on it, and with his tail hackles puffed up (second photo).  This dog gave ME hackles (goosebumps) because of his intensity and direct stare.  I believe his tail hackles symbolized that intensity. 

Tail hackles while staring at me with a side-eye.

Same dog staring at me while grabbing a leash - with tail hackles

I have noticed enough of a correlation between tail hackles and dog aggressive tendencies to make this a worthwhile inquiry.  I think a dog’s tail hackles get puffed up when that dog is very aroused or stimulated.  The source of the stimulation may be what the dog is going to be aggressive towards.  If anyone has other information about tail hackles and what they mean, or other observations about tail hackles, please reach out and let me know.   

To see a video that corresponds to this article please see my YouTube channel.

NOTE: I want to make it clear that I am NOT proposing every dog with tail hackles is dog aggressive or every dog without tail hackles is dog friendly.  So as always, there are many shades of grey to dog behavior. One must be able to read and understand dogs thoroughly to apply the possibility of tail hackles meaning aggression. I do not take one body cue and make a blanket statement about a dog.  I look at all the behavior the dog is showing and pair that with body language to make my assessment.