DOGS SMELL!

Ask, Apr 2004 by Moss, Meg

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.