Dogs: Seeing Through Their Noses


I recently decided to chastise myself the next time I grow impatient with my dog having to sniff a dozen spots along a walk, and stop to pee on several of them.  I’m enjoying another book on dogs, Inside of a Dog (and What Dogs See, Smell, & Know), by Alexandra Horowitz.  Her chapter on the way dogs see the world – through their noses – was fascinating and most telling.  I summarize here a few of her insightful details on how dogs discover and perceive so much more with their noses than I ever realized.  It’s interesting stuff:

Smells are minor blips in our sensory day compared to the reams of visual information we take in.  When we do notice a smell, it’s usually just good or bad, and rarely is it a source of information, other than what the source of the smell might be.  Dogs smell the world as we see the world, and then some.  Their universe is a stratum of complex odors at least as rich as the world of sight.  As they sniff and sniff, they are continually refreshing the scent, as though shifting their gaze to get another look.  Human noses have about six million tiny sensory receptors.  Dogs have two-to-three hundred million.  One example of what that difference makes:  We night notice if our coffee has been sweetened with more than a teaspoon of sugar.  Dogs can detect a teaspoon of sugar diluted in a million gallons of water, or two full Olympic-sized swimming pools.

With their Vomeronasal noses, dogs sniff to get information about the dogs and animals in their area, drawing in chemical information through pheromones – hormone-like substances released by one animal and perceived by another. From checking those hydrants and bushes all along the street, dogs can somewhat, or significantly, gauge another dog’s sex, readiness to mate, health, and possibly even their emotional state.  For dogs, humans are their scent, including familiar smells of clothing, soap, cologne, and more.  They can tell if we’ve been on a jog, had something to eat, been around other animals, and even if we’ve had sex! (not that they care).  They can identify individuals through smell, along with some of the characteristics of the individual and their emotions.  The fleeing criminal can be tracked by both his odor and his emotional distress!

So as to being more patient during that walk with my dog:  Unlike popular early theories, dog don’t always urinate to mark their territory – only maybe 20% of the time, and more often when courting or scavenging.  And yes, neutered dogs do this too because their brain function and instincts still carry on the business – to a point – that their reproductive organs can not.  They communicate and convey messages through their urine.  Chemicals in the urine give information about the aforementioned things – sexual readiness, etc. – and other things such as who the dog might be, how often he visits a spot,  and for the female dog, the male dog’s social confidence.  They scratch the ground afterward not to bury their business like a cat, but to add new odor to the mix and have it serve as a visual cue to a urine or feces spot for other dogs to find and examine.

As I said, fascinating stuff, even if perhaps more than you wanted to hear about the toilet habits of dogs.  Simply put again though, dogs emit/relay and gather social information very differently than we do.  The next time you try to hurry your dog on a walk, remember that you’re effectively shutting down his internet and cutting off his social networking time!

Roy Hovey


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