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 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!), check out this video by reactions:
Now that you understand why dogs sniff each other’s butts, find out why they eat grass and why they get the zoomies after a bath, then read up on some more fascinating facts about canines and unravel the truth behind popular dog myths.
A version of this story ran in 2018; it has been updated for 2023.