Can Dogs Smell Fear in Humans? - PetHelpful - By fellow animal lovers and experts
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Can Dogs Smell Fear in Humans?

Adrienne is a certified dog trainer, behavior consultant, former veterinarian assistant, and author of Brain Training for Dogs.

Can Dogs Smell Fear in Humans?

Can Dogs Smell Fear in Humans?

You may have been repeatedly told when you were a child to "never show fear to dogs because they can sense it." How true is that though? If you put that advice to the test by trying your best to appear confident every time you encounter an unfamiliar dog on a walk, chances are, this method worked and the dogs left you alone.

After several uneventful encounters throughout your life (thanks to negative reinforcement), you may have grown up thinking that dogs are blessed with mystical or paranormal powers that allow them to read your soul. Or, you may have grown up fearing dogs. In the back of your mind, you may have felt that dogs sense and seek submission or weakness, and as it happens when exhibiting fear, they will take advantage of your weakness and chase you down.

Can Dogs Sense Other Dogs' Fear?

First off, in order to determine whether dogs may sense fear in humans, it may help to get a glimpse into whether dogs can sense fear in other dogs. Apparently, dogs are well-versed in sensing fear in other dogs. When I worked at a veterinary hospital, we were often told that dogs can sense fear in other dogs, and, therefore, react accordingly.

I saw many dogs that as soon as they stepped in the hospital, they were very hesitant, some even bolted out the door refusing to come inside the examination room. Was that because they associated that place with some past painful procedures? It could be, but it couldn't be proven that all those dogs had such direct negative experiences.

Turns out, several dogs tend to act anxious at the vet's office because they communicate their fear and the fear passes along from one dog to another as efficiently as word-of-mouth. How can they do that though without talking to each other? It's not like Rover is warning other dogs by saying: "Hey, don't go in there, they will give you shots!"

The communication, in this case, is not verbal, but rather a gift of the dog's almighty nose. Actually, let's call it a form of teamwork between a dog's nose and another dog's rear-end!

The Power of Pheromones

This secret code of communication relies on pheromones. Pheromones are chemicals that are meant to trigger a social response in members of the same species.

Dogs are equipped with a vomeronasal organ (also known as Jacobson's organ), a special organ located in the nasal cavity which is purposely made for the detection of pheromones. When a dog is frightened, he or she secretes special alarm pheromones signaling danger which sends other dogs into high alert. These alarm pheromones are released by the dog's anal glands and trigger an immediate behavioral response in the receiver dogs sitting in the waiting room.

According to Alexandra Horowitz, author of the book Inside of a Dog, the anal sacs release involuntarily when dogs are frightened or alarmed. Despite those secretions being cleaned up with antibiotic soaps in veterinary offices, from Rover's perspective, those secretions still "reek of epic dog fear." Interesting, huh?

can-a-dog-smell-fear-in-humans

Can Dogs Sense Fear in Humans?

So, if dogs can sense fear in other dogs, can they sense fear in humans? While dogs are capable of detecting fear in other dogs, one must recognize that the goal of anal gland secretions is alerting other dogs of danger.

Thankfully, we humans don't have anal glands so dogs won't detect any involuntary secretions from down there, but can dogs sense fear in humans in other ways? Can perhaps dogs detect the smell of sweat? And when it comes to their other senses, can they hear our hearts beating faster or our increased breathing rate? Can they see our pupils dilate? Can they detect a surge in body chemistry such as the release of adrenaline? Can they detect the release of glucose in the bloodstream?

For sure, these questions have likely perplexed humans for years and are sure some interesting questions that are worthy of investigating. For a great part, many questions will remain unanswered, but here are some interesting thoughts.

Does Fear Have a Smell?

We can't deny that dogs are blessed with amazing senses—dogs have a remarkable sense of smell and it wouldn't be surprising if dogs could smell fear. However, we must first specify that fear is an emotion and an emotion doesn't have a smell. So, the correct question should be "can dogs smell the byproducts of fear?"

While fear is an emotion, one cannot deny that when a person is fearful, certain odoriferous changes take place. The question is, therefore, can dogs smell such odoriferous substances?

According to Jack George Thompson, author of the book The Psychobiology of Emotions, an animal may be capable of detecting a new odor but that odor will not provide much details about which emotion is causing it. It's, therefore, unlikely that an olfactory cue provides enough information for the animal to determine whether it's linked to fear. On top of that, it is unlikely that such an olfactory cue would be enough to incite aggression in the animal.

Nancy Diehl, an equine scientist at Penn State, seems to agree that it's unlikely that the smell of your fear could trigger a dog to react aggressively. She states:

"It is widely acknowledged that pheromone communication via the accessory olfactory system is possible only within animals of the same species. This limitation makes it impossible for any animal to smell fear in members of different species."

This suggests that just because a dog may sense an odor, doesn't mean he'll be more likely to attack you. More concerning is what you do when you are fearful as certain behaviors could trigger a behavioral response in dogs that may result in aggression. In the next paragraphs, we will be looking at some examples of fearful behaviors that could get humans in trouble around unfamiliar dogs.

When you smell coffee brewing, you're breathing in coffee molecules which bind to olfactory receptors in your nasal passages. Emotional states, including fear, are not typically regarded as capable of generating scent-laden molecules.

— Nancy Diehl, an equine scientist at Penn State

5 Behaviors You Should Avoid Doing Around Unfamiliar Dogs

Let's face it: Telling a child or person to hide their fear when an unfamiliar dog approaches often doesn't work. Fear is an emotion that can be difficult to control and trying to not be fearful can actually make the fear worse. Ever tried to keep cool when a rattlesnake is just a foot away?

Much more productive can be educating about behaviors that shouldn't be performed when around dogs. Telling a child to "be a tree" as suggested by the Dog Gone Safe bite prevention program may be more productive. Here are some behaviors you want to avoid doing when you're around unfamiliar dogs:

  • Avoid direct eye contact
  • Avoid making erratic movements
  • Avoid screaming
  • Avoid turning your back to the dog
  • Avoid running away

So What Is a Child to Do Instead?

The best thing to do around an unfamiliar dog is to stand motionless while keeping the hands folded around the chest. Avoid direct eye contact, look away. Act boring, just stand there like a street lamp. When the dog loses interest and is at a distance, slowly walk away. But what if the dog knocks you down? In that case, roll into a ball and be still as a log, suggests Dr. Barbara Sherman, a veterinary behaviorist at NC State University.

More Research Is Needed

It's natural to fear dogs you do not know. The fear may be triggered from a past negative experience with dogs, a fear of not having a situation under control, or simply not knowing this species well or actually having a phobia of dogs (cynophobia). While dogs may be capable of detecting changes in odor in fearful humans, this doesn't mean that they are capable of linking the odoriferous secretions with fear.

While there is ample research showing how dogs can be sensitive to perceiving human emotions, the proof is lacking on whether dogs could pick up on olfactory cues from humans and associate them with a precise emotion. However, when odor changes are combined with certain fearful behaviors, humans display, there are chances that these may elicit aggressive behaviors in certain dogs, hence the importance of knowing what to do to prevent a dog from attacking.

Study Says Dogs Can Really Smell Fear

While this article was initially written in 2015, a new study has shown promising, factual information in favor of dogs being capable of smelling fear. According to a study published on Animal Cognition, exposure to armpit fear-sweat collected from humans who were scared, caused in dogs more stressful behaviors, compared to exposure to happy-sweat from humans who were happy.

References

  • University of South Carolina: Smell myths: Can animals really smell fear?
  • NC State University: Behaviorist Urges Awareness to Protect Children from Dog Bites
  • Why Do Dogs Like Balls? By D. Caroline Coile, Margaret H. Bonham
  • D’Aniello, B., Semin, G.R., Alterisio, A. et al. Anim Cogn (2018) 21: 67. https://doi.org/10.1007/s10071-017-1139-x

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2015 Adrienne Farricelli

Comments

Lawrence Hebb from Hamilton, New Zealand on November 08, 2015:

Some good advice here, but I've been in situations where a dog was about to attack me and there was nothing I could do to prevent it so I made direct and quite aggressive eye contact, the dog backed off and ran away.

The key was that I wasn't actually scared and the dog knew it, but its not something I'd advise someone who doesn't know dogs to do.

Lawrence

Mary Craig from New York on October 19, 2015:

Funny how we've all bought into the "smelling fear"! You make so many valid points as always alexadry. How could they possible "smell" our fear?

So much we know about our good buddies, but oh so much we don't.

Thank you for another interesting look at dogs.

Michaela from USA on October 18, 2015:

I always figured that animals are really tuned in to our body language and can read our emotions or intent based on how we act around them. Not completely wrong after all... :)

Adrienne Farricelli (author) on October 18, 2015:

Thanks Bob for stopping by. It is an interesting topic, more research is needed, so yes, always good to give the benefit of doubt. One may wonder if after repeated experiences, a dog may start associating a certain odor with certain fearful behaviors exhibited by humans. Nancy Diehl says " This limitation makes it impossible for any animal to smell fear in members of different species." However, I feel that impossible is a strong word. I would assume as with any other topics that haven't been proven yet, it's better to stay open minded until more studies are out. Thanks for catching the typo!

Adrienne Farricelli (author) on October 18, 2015:

Pstraubie, yes, you are correct, this is about not making direct eye contact with a dog you do not know. A strong bond through eye contact is important and highly recommended to create with your dog, by making it a positive experience. In classes, we work on making eye contact a good thing from day one. That's the way we communicate with our dog and create trust and the foundational skills for a strong bond. Thanks for stopping by!

Patricia Scott from North Central Florida on October 18, 2015:

Does make one wonder doesn't it ?

The whole not making eye contact thing too is up for discussion ....not long ago I read that dogs communicate with us via their eyes....creating a stronger bond...and so I have begun to look into my doggie's eyes often. Perhaps the not looking into a strange dog's eyes may be wise...though.

We may never know the answer to smelling fear in humans but I definitely believe they can sense fear by our body language and behavior.

Angels are on the way to you this morning ps

Bob Bamberg on October 18, 2015:

Really interesting hub, Adrienne. I've always accepted the notion that dogs can smell fear in us, reasoning that they can detect the changes in our body chemistry when we're frightened. But I've also always felt that our body language, however minor, were cues to the dog, which is a master at reading body language.

After reading your hub, I'm less inclined to believe that odors we emit can trigger aggression in dogs. After all, the alarm pheromones released by dogs seem to trigger a fear response in other dogs, not aggression. Interesting stuff. You might revisit the fourth line in the fifth paragraph. Regards, Bob.