Creature Feature

Arkansas Democrat-Gazette dog smelling illustration.
Arkansas Democrat-Gazette dog smelling illustration.

When we're out walking, my dog sniffs everything along the way. Sometimes he'll smell something, then rub his head on the ground where he was sniffing. Once he even flopped down and rolled in something really stinky. I couldn't tell what it was, but I had to give him a bath when we got home. Why did he do that?

When dogs sniff, drop and roll, the results can be unpleasant for us humans although extremely pleasant for them. My dainty Pomeranian once excitedly flopped to the ground to roll, wiggle and wallow in something very dead, then dashed back to me in a tizzy to let me sniff the wondrous foulness. Naturally, I didn't share her delight, although watching her was entertaining.

Dogs live through their noses, Alexandra Horowitz says in Being a Dog: Following the Dog Into a World of Smell. Horowitz makes it her business to learn as much as she can about dogs and their senses as head of the Dog Cognition Lab at Barnard College in New York. In her book, she shares a wealth of information about dogs and their sense of scent. Like others in the field of canine science, however, she hasn't pinpointed the reason dogs like rolling in things that reek.

Horowitz says the smelly things dogs find desirable make no sense to us because they have no common denominator, plus they can be things that actually aren't stinky -- bed pillows, hard candy and raisins, for example. But dogs typically go for odoriferous matter that repels us -- particularly the decaying remains or waste of other animals. Theories abound as to why. Among them is that dogs are trying to camouflage their own scent by matching the smell of their bodies to the aromas of a particular environment.

Another theory suggests dogs might believe that being covered in something malodorous enhances their appeal to others of their kind. The last theory, which also is the one most commonly accepted, is that rolling in a deep stink is hedonistic; in other words, it's all about the pleasure.

Horowitz's book covers a lot of ground and includes revelations about canines' most "nosy" preferences. She explains that while there are dogs trained to follow the scent of humans living and dead, dogs actually prefer sniffing other dogs to sniffing people. No doubt you've noticed that when two dogs meet, they sniff each other as a greeting and introduction.

Dogs pick up on the scent of other dogs immediately, although to us they may simply smell a little or a lot doggy. Even if you have a dog that seems to have no perceptible odor, you can detect his unique aroma if you get close enough. That signature scent is due to secretions of the apocrine glands in the hair follicles covering the dog's body.

A dog also has a one-of-a-kind smell at the bottom of his foot pads, which you likely won't notice unless you put your nose to the foot pad and take a good long whiff. Even then, the dog's smell might be too subtle for the human nose, which has a mere six million scent receptors compared to 300 million receptors in a dog's nose. But dogs have no trouble detecting the scent markers left when other dogs scratch the ground after doing their business. Secretions from glands in their paws and between their toes leave clear identifying markers for other dogs who happen by.

When a dog inhales another dog's aroma, he's not only able to tell if the second dog is male or female, but also can discern the dog's age, emotional state (scared, happy or anxious) and if the dog has been recently ill. Dog to dog, their noses know if a dog has eaten, had a bath, has been petted by one or many humans, or has been visited by any other dogs.

With scent, dogs put their lives on display for other dogs. They share the stories of their lives by marking inanimate objects with urine. When your dog stops and sniffs sign posts, rocks, curbs, fire hydrants, tires and numerous other objects when you're out for a walk, he's reading the doggy equivalent of a Facebook newsfeed. He also leaves his own posts for other dogs to follow.

While it's clear dogs are sending messages, researchers continue to search for the complete algorithm.

Family on 12/21/2016

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