Smell
Dogs experience the world nose-first
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© Deb Smith
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How does a dog get the neighborhood news? Through its nose! Of all a dog's senses, its sense of
smell is the most highly developed. Dogs have about 25 times more olfactory (smell) receptors than
humans do. These receptors occur in special sniffing cells deep in a dog's snout and are what allow a
dog to "out-smell" humans.
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© RONCO/Washington
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Dogs can sense odors at concentrations nearly 100 million times lower than humans can. They can
detect one drop of blood in five quarts of water! Sniffing the bare sidewalk may seem crazy, but it
yields a wealth of information to your dog, whether it's the scent of the poodle next door or a whiff
of the bacon sandwich someone dropped last week.
When a dog breathes normally, air doesn't pass directly over the smell receptors. But when the dog
takes a deep sniff, the air travels all the way to the smell receptors, near the back of the dog's
snout. So for a dog, sniffing is a big part of smelling.
In the wild
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© Monty Sloan/Wolfpark.org
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Wild canines rely on smell for hunting. They also use smell to
decode scent messages left by other animals -- friend or foe, predator or prey. A wild canine's
sense of smell is especially important in habitats where seeing prey is difficult such as
the thick underbrush of forests.
Here at home: sniffing dogs
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© US Customs Service
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A dog can sniff out all sorts of smells that human noses miss.
Because of this keen sense of smell, we can train them for jobs such as tracking, rescue,
or drug and bomb detection and to detect a wide variety of specific scents, such as drugs,
fruits or the feces of particular animals. Dogs that make a living by sniffing are trained
to alert their handlers to the presence of these things by pawing, barking, or in the case
of something dangerous, sitting quietly. They are trained by the promise of a favorite
toy or play time each time they successfully sniff out the target scent.
