Your dog’s nose knows: That amazing canine computer

By Jeff Stallings, CPDT-KA

Yesterday while at the beach my 15-month old dog suddenly turned, sniffed the air and ran towards another dog that was about 50 yards away, at full clip.  These two young dogs instantly began whining with joy and playing with abandon in ways I had not seen Otis play in many months.  I asked the other owner his dog’s name, and when said “Scout”, something clicked.  When I realized that Scout was a female, it all fell into place:  Almost a full year ago, as 4-month old puppies, Scout and Otis had met only once, at a puppy social, and had hit it off immediately and played for about 15 minutes in much the same way we witnessed yesterday. 

While it is doubtful they remembered that actual play session all those months ago, they did recall each other’s scents and that this particular smell was associated with a positive, fun experience.

Your dog's brain is wired for smell

How are dogs able to detect scents and remember the emotions associated with them?  Well, you can think of a dog’s sense of smell as being roughly as important and primal to them as sight is to us.  The portion of our brain that is dedicated to vision is instead dedicated to olfactory functioning in dogs. 

You’ve probably heard that dogs can “smell fear”, and in fact they can, as well as anxiety and sadness and other human emotions. We release hormones in response to many emotional states, including stress and fear, and dogs detect these hormones clearly and instantly. (This is why your calm, positive state of mind is a crucial part of effective dog training.)

Here are a few facts about the dog’s olfactory abilities, paraphrased from Alexandra Horotitz’s book “Inside of a Dog:  What Dogs See, Smell and Know”, which I highly recommend to all dog owners:

  • Humans have only 5 million olfactory receptors; dogs have at least 250 million, providing a “resolution”, if you will, thousands of times more powerful than our own. Dogs have more genes than us committed to coding olfactory cells, more cells, and more kinds of cells able to detect more kinds of smells.

  • We might notice if our coffee has been sweetened with a teaspoon of sugar; a dog can detect a teaspoon of sugar diluted in a million gallons of water, two Olympic swimming pools full!

  • While we humans quickly get used to an immediate smell (brewing coffee for instance) so that we quit smelling it at all, the dog’s nose has no such limitations.  The sniffing method of dogs enables them to avoid habituation to the olfactory topography of the world; they are continually refreshing the scent in their nose, as though shifting their gaze to get another look. This is why a bloodhound can easily track humans or other animals: Instead of becoming inured to smells over time, as we do, a special organ in the dog’s nose keeps the scent fresh.

  • We needn’t even touch objects for them to smell of us:  As we move, we leave behind a trail of skin cells.  The air is perfumed with our constantly dehumidifying sweat.  To a dog, we wear in odor what we have eaten today, whom we’ve kissed, what we’ve brushed against. Dogs find it incredibly easy to distinguish us by our scent alone:  These skilled sniffers see us in the cloud of molecules we leave behind.
Jeff Stallings, CPDT-KA

My Blog/Articles page includes other posts I have written in the past decade or so. These posts highlight my philosophy, beliefs and methodology regarding dog behavior and training.  Thanks for reading!

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