Why Do Dogs Sniff Each Other's Butts?

Chloe Effron // Dogs: iStock
Chloe Effron // Dogs: iStock

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

We might giggle when we see dogs sniffing each other’s rear ends, but there’s a good reason why dogs stick their noses in private places. It lets them find out all kinds of things about each other to help them get along and survive. A butt sniff for dogs is like a handshake for humans.

Dogs’ amazing sense of smell is 10,000 to 100,000 times better than humans. They also have a special part of their noses called the Jacobson's organ that lets them ignore the smell of poop when they sniff another dog’s rear. Instead, the organ detects something more important. On the sides of a dog’s anus (AY-nuss)—the place where poop comes out—are special glands that release chemicals telling the body how to grow and work properly. This is what interests dogs the most about each other’s butts. 

The chemicals tell dogs a lot about each other. They help a dog to know if another dog is male or female, how old it is, what it eats, how healthy it is, and even what kind of mood they’re in. The chemicals also help it to know if other dogs are strangers or if they’ve met before. All of this helps dogs decide how they should behave. It's how dogs first get to know each other!

To sniff out more information about dogs and their noses (and their butts!), see this video by Reactions.

Get Into the Halloween Spirit With Harry Potter and Star Wars Costumes and Accessories From Hot Topic

Hot Topic
Hot Topic

Halloween is fast approaching, and that means it's time to start picking up those decorations, planning your costume, and settling down for a few monster movie marathons. Hot Topic is already way ahead of you, with a selection of costumes and accessories based on fan-favorite movies and TV shows like Harry Potter, The Nightmare Before Christmas, Stranger Things, and Hocus Pocus. We've picked out some of our favorites for you to check out below.

Harry Potter

1. Beauxbatons Hat and Cape Uniform; $60

Hot Topic

If Fleur Delacour is your favorite character from the Triwizard Tournament, then this look is for you. Beauxbatons baby blue hat and cape can now be yours to prance around in and pretend you're from the magical French academy for young witches.

Buy it: Beauxbatons Hat, Beauxbatons Cape

2. Hogwarts Zip-Up Hoodie Cloak; $55

Hot Topic

One of the most iconic parts of the Hogwarts uniform is the cloak. The sweeping black robes looked so official and mystical in the movies that it almost seems wrong not to wear one if you want to be a Hogwarts student for Halloween. These hoodie cloaks are available in all four house colors.

Buy it: Hot Topic

3. Hogwarts Cardigan Sweater; $49

Hot Topic

Much like the cloak, the sweater vests and cardigans the students at Hogwarts got to wear are essential to any costume. You can choose from the four house crests and colors, so you can show your allegiance while also making a fashion statement.

Buy it: Hot Topic

4. Hogwarts Plaid Skirtall; $45

Hot Topic

Though this isn't a look you'd recognize from the Harry Potter movies, these plaid skirtalls—skirt overalls, basically—feature the crest and colors of whichever house you represent.

Buy it: Hot Topic

Star Wars

1. The Mandalorian Helmet; $17

Hot Topic

With the second season of The Mandalorian coming out right in time for Halloween, going as one of the show's main characters is a no-brainer. And since you probably can't pull off the Baby Yoda look, this simple Mando helmet is your best option.

Buy it: Hot Topic

2. Yoda Pet Costume; $20

Hot Topic

Baby Yoda is easily the cutest thing to emerge from the new Disney+ series, and there's no shortage of merchandise with that little green face plastered across it. From Amazon Echo Dots to slippers to LEGO sets, the little rascal is everywhere. But if you're more a fan of classic Yoda, you can impose your love of the character on your dog with this costume, complete with floppy green ears and tiny Jedi robe.

Buy it: Hot Topic

3. The Force Awakens Rey Costume; $48

Hot Topic

Rey represents a new generation of Star Wars hero, and her costume during her time on Jakku from The Force Awakens is still her most iconic look. It's also a costume that's simple enough to throw on for Halloween and still feel comfortable in.

Buy it: Hot Topic

4. R2-D2 with Pumpkin Decoration; $50

Hot Topic

When trick-or-treaters stop to collect candy from your house, greet them with this inflatable R2-D2 decoration that's primed for Halloween. Standing around 3 feet tall, this will show off your love for a galaxy far, far away and your holiday spirit.

Buy it: Hot Topic

The Nightmare Before Christmas

1. Sally Scrunchies Set; $10

Hot Topic

If you're looking to embrace your The Nightmare Before Christmas love in a more subtle way, opt for these Sally-approved scrunchies that embody the colors of the movie without going too far overboard.

Buy it: Hot Topic

2. Jack Skellington Button-Up Shirt; $35

Hot Topic

If Jack Skellington is your ultimate fashion hero, then this button-up pinstriped shirt is the ticket for you. It mimics Jack's look right down to the unique bat-shaped collar.

Buy it: Hot Topic

3. Jack and Sally 'Love is Eternal' Eyeshadow Palette; $17

Hot Topic

Makeup inspired by your favorite characters is the key to completing a Halloween look, and this palette will help you make a colorful, smokey eye featuring shades seen in The Nightmare Before Christmas. You can even use these colors long after Halloween is over once you've mastered your favorite style.

Buy it: Hot Topic

4. Zero Dog Costume; $29

Hot Topic

The real star of The Nightmare Before Christmas has to be the dog, Zero, and now you can drape your own pooch in the ghostly visage for under $30.

Buy it: Hop Topic

Other Categories

- Stranger Things
- Coraline
- Disney
- Haunted Mansion
- Hocus Pocus
- The Craft

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100 Fascinating Facts About Earth

The best Spaceball.
The best Spaceball.
NASA

Did you know that there’s a place in the South Pacific Ocean called Point Nemo that’s farther from land than any other point on Earth? So far, in fact, that the closest humans are usually astronauts aboard the International Space Station. (And by the way: The map you’re about to look for Point Nemo on might not be entirely accurate; a certain amount of distortion occurs when trying to depict a 3D planet on a 2D surface.)

In this all-new episode of The List Show, Mental Floss editor-in-chief Erin McCarthy is journeying to the center of the Earth, and visiting its oceans, its atmosphere, and even space, in search of 100 facts about our endlessly fascinating planet.

The subjects that fall under the umbrella of “facts about Earth” are nearly as expansive as Earth itself. Geology, biology, astronomy, and cartography, are all fair game—and those are just a few of the many -ologies, -onomies, and -ographies you’ll learn about below. 

Press play to find out more Earth-shattering facts, and subscribe to the Mental Floss YouTube channel for more fact-filled videos here.