Dogs: Wolf, Myth, Hero, Friend

Evolution and Diversity

Canine Communication

Form and Function

Research and Conservation

Your Job

Dogs Helping People

About the Exhibit



Dogs experience the world nose-first

A dog learning to discriminate smells - accuracy is positively reinforced with toys or treats
© Deb Smith

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.

A dog sniffing out a landmine
© RONCO/Washington

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

Wolves sniffing on an icy snowfield
© Monty Sloan/

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

A US Customs dog and officer after having sniffed out contraband - US Customs dogs are responsible for busts of millions of dollars each year
© US Customs Service

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.

Activity Flying frisbee

Try This at Home

Can you rely on your sense of smell to solve a mystery? Put on a blindfold. Have a friend or family member hold up different types of food or spices to your nose one at a time. Can you tell what each "mystery item" is just by smelling?

The Natural History Museum of Los Angeles County (logo)

This exhibit and national tour of Dogs: Wolf, Myth, Hero & Friend is made possible by PEDIGREE® Brand Food for Dogs.
The exhibit is also supported by a generous grant from the National Science Foundation.
Additional support for the Los Angeles presentation is provided by The Brotman Foundation of California.

Page updated: 6 May, 2004