Rusty
 
Meet Rusty Barker. He's a terrier, a kind of dog whose original purpose was to keep rats away from farms and houses. These days most terriers are just household pets, but they still know how to sniff out a rat!

Of course, Rusty's not his real name, because he's a dog. When dogs are talking to each other, they use smell-names, not sound-names. But he knows that when humans say "Rusty," that means him, so that's what he answers to.
 
Smells, Smells, Smells
 
What's it like being a dog like Rusty? It's not like being a grown-up. It's not like being a child. It's not like being an alien, either.

Dogs are like us in a lot of ways. They can see, hear, and feel most things that we can. But they also have a superpower: their sense of smell. That's why they sniff things all the time.

Most animals live somewhere in the World of Smells.

You and I live in the World, which is everything we can see. Dogs, cats, mice, snakes, ants, moths, and lots of other animals mostly live in the World of Smells, which is the same World as ours, but much, much stinkier.

It's full of poo smells, pee smells, leaf smells, sweaty foot smells, and loads of other stinks that we don't even have names for, because our noses aren't as smart as theirs.

The first thing humans notice is usually what things look like. But dogs mostly care about what things smell like. That's why you like watching TV and YouTube, and dogs don't. YouTube for dogs would have to literally be a tube with stinky smells coming out of it all the time.

Yuck, you're thinking. That would mean that YouTube for dogs would make your house stink like a gigantic fart. But actually, it wouldn't have to, because dogs' noses are so sensitive that they'd only need a tiny amount of each smell, such a small amount that you wouldn't even know it was there.

A dog's eyesight isn't as good as yours, and they couldn't care less if something is pink or blue, just so long as it smells interesting. That's why the pictures in this book are in black and white, because that's roughly how dogs see things. Smells are their colors. Their sense of smell isn't magic, it's just a way of experiencing the world differently to you.

Put it another way: Just because you can't see something doesn't mean it doesn't exist. You know how to use the TV remote, don't you? (OK, probably better than your parents do.) You can't actually see the remote talking to the TV, but it must because the TV does what the remote tells it to do. The remote talks to the TV using infrared light, a kind of light that your eyes can't see.

Well, that's a bit like how smells are for dogs. There are loads of smells that dogs find really exciting, but we have no clue about, because they are just too weak for our noses.
 
Early Morning
 
When Rusty wakes up in the morning, he sniffs the air before he even opens his eyes. His nose tells him that no one has come downstairs yet, because none of the people smells have changed from last night. It's not walk time yet!

A few moments later, Mum comes downstairs in her dressing gown and opens the door to the garden. Out goes Rusty. He's desperate for a pee, but first he has to have a sniff around the garden to discover what's happened out there while he's been asleep.

Right away, he arrives at a place where he can smell that a cat has been walking across the lawn during the night. There's nothing to see, no dents in the grass or yucky furballs, but Rusty's nose lets him trace every pawprint that the cat made, just from the little bit of cat foot smell left behind (which I guess to a dog, is much sweeter-smelling than human foot smell. Let's blame socks. And don't even mention welly boots. Sorry, back to cats). Rusty can even tell which way the cat was moving, just from the differences between the smells of her pawprints. The fresher they are, the stronger the scent, so the direction she's gone in is smellier than the direction she came from.

The World of Smells is always changing.

Mice have been scuttling about during the night, marking their trails with little spots of pee.

A twig sits on the lawn, a sappy smell coming from where a clumsy pigeon broke it off from the tree above.

There's the smell of cut grass in the corner from when Dad mowed the lawn yesterday.

A wrapper that just blew in from the street smells of strawberry.

Next time you're in a garden, try crawling around with your nose to the ground, sniffing as you go. That way you'll get a bit of an idea of what it's like to be a dog, although your human nose won't give you much of the detail.

It would be like always being close to something really smelly--a vase of flowers, chocolate brownies straight from the oven, a really bad fart (fingers crossed it's brownies!).

And all these smells alter with the wind and the weather, which means they change and shift all the time. This makes for a very exciting morning for Rusty.

He can tell straight away that it rained the night before, and not just because his paws are wet, but because there are even more interesting smells around than usual. Rain washes old smells out of the ground and plants' leaves, reminding Rusty of things that happened a few days ago.

That's a bit like when your mum and her friends flick through loads of photos on their phones when they meet up. Except that dogs don't need to take pictures, because they remember everything their noses tell them!

You can see how important smells are to dogs just by looking at their nostrils, where the air goes in and out. Yours point downward. Maybe this is to keep the rain out, but it also means your nostrils can't be pushed up against things to get all the details of the smell. Not unless you want people staring at you.

Anyway, most of the time you keep yours way up in the air, which is not the best way to capture all the lovely smells near the ground. Dogs can lower their heads right down to the ground, and their nostrils point forward so that they can sniff what's right in front of them. (Dogs' nostrils are called "nares," which rhymes with "fairies.")

But it's the inside of their noses where dogs are so much better equipped than we are. The air that they sniff into their nostrils swirls through a special 3D maze made of bones called "turbinates." If you could lay the maze out flat, it would be roughly the size of two smartphone screens. That's an amazing amount of surface to cram into a small head.

The walls of the maze are covered with eight hundred different kinds of smell detectors. Smell detectors are microscopic hairs that stick out of the surface of the nostril-maze and catch the smells as they go by. If it's the kind of smell that matches that kind of detector, the other end of the hair sends a message to the brain ("roses," "poo," "newly mown grass," or "garlic"--and lots of others).

We actually have the same detectors that dogs do, but only a few hundred of each. Dogs have about a million of each kind, and almost a billion altogether. That's why they're so much better at smelling than we are.

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Excerpted from A First Guide to Dogs: Understanding Your Very Best Friend by John Bradshaw
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