DOGS SMELL!

Yes, indeed they do. Up to 10,000 times better than humans, in fact. That is, their noses work better. (We all know what dogs smell like, but that's a different story.)

The Nose Knows

The minute you open the door, you know someone is baking cookies. Your nose tells you that they are chocolate chip. But how does your nose know? The aroma of the cookies actually reaches your nose as tiny chemical particles called molecules. Inside your nose are special receptors-5 million of them-that react to the chemical particles and send a message to your brain. Some scientists think that the molecules for each scent are a different shape and that they must fit into the right receptors to be analyzed correctly Once this happens, your brain then recognizes the odor: OH BOY! CHOCOLATE CHIP COOKIES!

A dog's nose works the same way, but its 200 million or so scent receptors make it much more sensitive than the human nose. The longer the dog's nose, the more scent receptors it has and the better it can smell. Dogs with the best sense of smell, such as beagles and bloodhounds, sometimes called "scenthounds," have long snouts that house a complicated network of tissues, mucus, and scent receptors that enable a dog to recognize its favorite smells: OH BOY! DEAD SQUIRREL!

Even on the outside, the dogs wet nose is marvelously designed to help it smell better. Its moisture attracts and holds scent molecules, which then can travel up the nostrils. Ever wonder why dogs sniff so much? Sniffing helps to stir up scent particles so that the dog can inhale them. If you look closely at a dog's nose, you'll notice slits at the corners of each nostril. By flaring out, these slits enable more air to circulate around the nostrils and really make the scent strong. The extra-long ears of scenthounds also help them smell: as they drag along the ground, those floppy ears stir up scent molecules for the dog to inhale.

Telling by Smelling

Smell is a dog's sharpest sense. Next time a dog sniffs at you, think about this: just by smelling, a dog can tell where you have been and what you have been doing, what you have eaten, and even whether you are not feeling well. (Perhaps it's a good thing that dogs can't talk.) The dog is using its nose the way you use your eyes to recognize people and figure out something about them. You know your little sister just came home from school because you see that she has her B backpack on; she had peanut butter and jelly for lunch because it is all over her shirt; and she looks might have a cold. A dog's nose enough to detect the scents your little sister picked up at school, the pb and j, and even the chemical changes that take place in her body if she is ill.

When you see two dogs meeting, notice how they sniff each other. Their smells tell them everything they need to know and whether it is safe to be friendly or if they should stand back.

Drugs, Bombs, Pineapples?

In the wild, a good nose is a tool for survival. The first dogs relied on their powerful sense of smell to track prey and locate food. Wolves and wild dogs still do today. Once humans recognized the dog's astounding ability to smell, they learned to make use of it. People began to breed dogs with specialized smelling skills. And though the scenthounds make excellent hunting and tracking dogs, other dogs are nasally gifted as well. St. Bernards, for instance, can track lost hikers in the snow. German shepherds and Labrador retrievers make excellent canine cops, trained to use their noses to track criminals and to find evidence.

A Dog's World

Even though modern dogs don't live in the wild anymore, their senses still work as if they did. For instance, dogs have a great sense of smell because their ancient ancestors used their noses to hunt and find food. Can you figure out how the dog's other senses-eyesight, hearing, touch, and taste-might have helped in the wild?

Whiskers are actually highly sensitive "feelers" connected to nerves on the dog's face. Why?

These special hairs help dogs locate food on the ground that they can't see They detect the slightest change in air flow.

Dogs can't taste a lot of different flavors because they have fewer taste buds than you do. They can only tell when food tastes good or bad. And they have a special ability to taste the differences in water. Why?

Food in the wild doesn't have to be delicious, but it should be fresh (tastes good). Spoiled food (tastes bad) can make a dog sick. So can impure or polluted water.

Dogs can't see as many colors as you can, but they are really good at detecting movement and seeing well in low light. Why?

In the wild, most prey is brown or tan, so seeing color isn't as animal while hunting at night.

A dog's ears are specially designed to scan for distant sounds and then zero in on them in a split second. They can also hear very high-pitched noises that you can't. Why?

Being able to hear danger or dinner from far away can mean the difference between life and death in the wild. Rodents (yum) make high-pitched squeaks that only dogs can hear.

But good "detector dogs" must have more than just a super schnoz. To sniff out illegal or dangerous materials, the police and other law enforcement agencies use dogs that can be trained to remember certain smells and distinguish them in a crowd of other aromas. These dogs can even detect very weak smells. A well-trained beagle, for instance, can remember up to 50 scents and pick them out from a complicated blend of odors. The U.S. Department of Agriculture trains an elite "Beagle Brigade" to patrol airports and sniff travelers' luggage for illegal plants and produce that might bring dangerous pests or diseases into the United States. These little scenthounds are so cute that they can go about their work without frightening people. Sixty teams of beagles and their handlers work 21 airports around the U.S., where the dogs' sharp noses detect about 75,000 illegal agricultural products each year.

Other detector dogs are trained to find illegal drugs, bombs, and chemicals. Some dogs can even be trained to smell out money. These dogs (and their handlers) must undergo months of special schooling to learn how to locate, recognize, and signal the odors that mean DANGER. Some dogs even go to college: Auburn University in Alabama has a special Canine Detection Training Center. It runs a breeding program as well, where puppies are raised from birth to be healthy and skillful detector dogs. Other dogs attend "K-9" training centers run by police agencies.

Dogs can be trained to find people, too. Search-and-rescue dogs perform amazing feats in locating lost hikers or earthquake victims buried under mounds of rubble. Although we share certain human scents, people all smell different according to their body chemistry and whether they are afraid, or anxious, or feeling guilty. A dog can smell these differences in the odor of human sweat, so dogs can be used to track and find particular people, a lost child or an escaped criminal, for instance. With even the smallest clueflakes of skin or scraps of clothinggood tracking dogs can pick up and follow a scent over many miles. In trails less than three hours old, they can even determine the direction the person was traveling.

Dr. Dog

Researchers were recently amazed to learn that it may be possible for dogs to detect certain kinds of cancer and other diseases in humans. It all started about 15 years ago when a woman in England reported to her doctor that her dog had repeatedly sniffed and even tried to bite a mole she had on her leg. The doctor removed the mole and discovered skin cancer. Since then, studies have shown that dogs can indeed scents associated with cancerous tumors. They may even be able to identify a cancer patient by smelling his or her breath or body odor. Researches also suspect that dog can warn their owners of seizures, or sudden attacks of certain diseases. Chemical changes in the body before a seizure interfere with a persons normal smell, but only the sensitive nose of a dog can detect such changes. A companion dog trained to give such warnings could save the life of an epileptic or anyone who suffers chronic seizures.

By a Nose

But it isn't just their noses, or their scent memories, that make dogs perfect for these tasks. Many dogs are easily trained and take to the work of scent detection as if it were a game. Let's face it, they just love to sniff and whiff and snuffle and snort. It's what dogs do.

Copyright Carus Publishing Company Apr 2004
Provided by ProQuest Information and Learning Company. All rights Reserved