Nosebook

Canine Social Media

Story and Photos by Mary Terra-Berns

As soon as my dogs and I are out the door every day, usually before the sun is up, their noses are a nanometer off the ground, analyzing what you might call the social media posts left during the night.

Knowing how much time I spend on interesting posts, I try not to hurry them on our walk in the outskirts of Coeur d’Alene when an intriguing message requires a few extra minutes for them to review. Think Sniffchat or Nosebook.

As I watch my dogs (both rescues: a German shepherd and German shepherd/Labrador mix) zigzag along the road, I know they’re analyzing who travelled through their neighborhood and what stories they left.

Each message left strategically along the road by the night-shift receives a few minutes of intense nasal scrutiny. One particular blade of grass gets a lengthy review. What is different with this blade of grass compared to the hundreds of others around it is a mystery to me.

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Collecting messages left on the trail.
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Even winter doesn't faze the dogs' noses.
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The author's dogs, Tsuga (left) and Pico.
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On the scent.
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In my training as a field biologist, I learned that dogs “visualize” their world through their olfactory abilities. Their superior sniffing skill comes from complex structures in the nasal cavity called turbinates: scroll-shaped bone covered with a spongy membrane of scent-detecting cells and nerves. Air that circulates over the turbinates deposits scent molecules on the membrane and the incoming information is then transported to the brain.

Humans have turbinates, too, but they’re dreadfully inferior to those of canines. Dogs have 125 million to 300 million scent receptors in their nasal cavity, while humans have a mere five million.

Dogs can remember what smell goes with whom or what long after they initially register it. For example, when my neighbors got a new dog, at first all of his scent-marking posts received intense scrutiny from my dogs. Now, however, they recognize his markings and give them only a quick sniff and a responding post.

With dogs, breathing and sniffing are two different functions. Tracking dogs have to learn how to breathe and smell simultaneously, in order to maintain stamina while following a scent on a long-distance search.

When they exhale, some of the scent-laden air remains in the nasal cavity until the concentration of scent molecules is sufficient to identify an odor or to log a new one into their scent library.

Incoming scent-laden air molecules are analyzed in an area of the brain about the size of a piece of copy paper. In a human, it`s about the size of a postage stamp. So it makes sense that the part of a dog’s brain controlling smell is forty times larger than that same part of a human brain.

During searches, handlers have to make sure dogs don’t overheat, which is good advice in any circumstance, but the special importance of it for a search dog is that its sense of smell can be reduced as much as forty percent when it starts using inhaled air to cool itself rather than to follow a scent.

 In addition to turbinates, dogs have what’s called the Jacobson’s organ in their nasal cavity. This organ allows a dog not only to smell but to taste moisture-borne scents. It’s used primarily to detect pheromones from animals and hormones from humans. Assessing moisture-borne scents is how a tracking dog differentiates humans from other animals.

Dogs track humans by focusing on epithelial or skin cells. Humans shed approximately thirty thousand skin cells every minute, even when fully clothed, which adds up to around forty-three million cells per day! Bloodhounds are trained to follow footsteps but other tracking dogs are trained to follow a scent profile.

For canines, a scent profile is like reading a story, like retaining every detail from a book instead of simply reading the study guide. Dogs don’t just smell a chocolate chip cookie—they smell the flour, sugar, salt, butter, eggs, vanilla, and chocolate. They follow not only all of those sloughed-off skin cells of humans but other details such as disturbed ground and broken blades of grass.

Their two nostrils move independently, which allows them to determine what direction the scent is coming from. By scanning for negatives, or declines in scent, they can determine in what direction to continue the search.

Thanks to this awesome scent memory, dogs can search and locate people, crime scene evidence that has human scent, as well as wildlife and the sign that they leave, such as scat, which is beneficial for helping indicate habitat use by endangered species. Of course, bird hunters also appreciate a well-trained canine nose.

Every day on our walks, both of my dogs respond to certain messages with their own posts before they move down the road to the next message. Occasionally, I can tell who left a post but typically I’m clueless. I wish a thought bubble would pop up over their heads with the post details, so I could catch the overnight news.

 

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Mary Terra-Berns

About Mary Terra-Berns

Mary Terra-Berns is a freelance writer and biologist with a Masters degree in fish and wildlife sciences. She has worked with rare species such as wolverines, Canada lynx, red-cockaded woodpeckers, and many not-so-rare species. An Idaho native, Mary enjoys hiking, fly-fishing, running, skiing, snow shoeing, and traveling. Her Trail of the Coeur d’Alenes guidebook can be purchased at xpertguide2.com.

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