Why do dogs sniff each others bums

We've all seen dogs sniffing each other's butts. Big dogs, little dogs, fluffy dogs, sleek dogs. They. All. Do. It. Little dogs seem especially delighted to sniff the nose-height butt of a larger dog. It's so convenient! Meanwhile, the humans who come along with the dogs for walkies are left to stand awkwardly by, laughing in embarrassment and saying things like, "Yeah, he does that."

But there's no need to be embarrassed, humans. This butt-sniffing routine is no different from you using your eyeballs to note someone's hair and clothing. Dogs can even determine the mood of another dog through butt sniffing, the same way we might notice another human's mood by seeing a smile or a frown. Let's find out how they do it.

Super Sniffers

Dogs are far, far better at smelling things than people. Where humans have about 5 million olfactory receptors in their noses, dogs have 150 million to 300 million, depending on the breed. Bloodhounds, for example, are some of the best canine sniffers. About a third of a dog's brain is devoted to processing these scent signals, while a human only uses 1/20 of their brain for smells.

Dogs also have a special area in their snout called a Jacobson's organ, or more officially, the vomeronasal organ. It has openings in the roof of a dog's mouth and a direct connection to the dog's brain. But it doesn't pick up smells the way we think of them, like lavender or gasoline wafting on the breeze. This organ does something more like chemical analysis on the molecules that enter it. This is how dogs can read gender, mood and health of another dog.

Butt How?

Near the base of their tails, dogs have anal sacs. They are horribly smelly to humans, so you probably assume that's what dogs are going for with the butt sniff. Especially beagles, who seem to have never met a foul smell they didn't want to roll in.

Butt no! The smells we smell are not what dogs are after. Those glands are apocrine glands, and humans have them too. Dogs don't even really take note of the poopy smell; that's just another smell. They're looking for the information contained in the pheromones manufactured by those glands.

These chemicals are processed by the Jacobson's organ — which, remember, doesn't process smells as we know them. This chemical cocktail is what dogs "read" to learn another dog's gender, mating status, mood, health, what they've eaten lately and probably much more. There are apocrine glands all over a dog's body, but those two butt sacs are the easiest to access.

Now That's Rude

Humans have apocrine glands too, but not as many as dogs. Ours are in our armpits and – you guessed it – our crotches. As we've seen, dogs will head for the easy-access smell, which results in the always unwanted crotch sniff. Dogs will more often sniff the crotches of people they don't know in order to get to know them better, which does not make it one bit less awkward.

You arrive at the dog park with your furry best friend. He hops out of the car and is shaking in excitement. His nose moving a million miles a minute to sniff the air around him. He practically prances over to the park gate, and you let him in. He charges ahead and a known friend comes running up to him. They start circling each other and… Here it comes! They’re sniffing each other’s butts and are ecstatic about it! Every dog owner has experienced this awkward (to humans) social ritual of dogs, but why do dogs sniff butts in the first place? Read on to learn why dogs sniff butts so you understand why your dog does this weird (to you) behavior.

6 Reasons Dogs Sniff Butts

Dogs have stronger olfactory senses than humans do – 150 million olfactory receptors to human’s puny 5 million. They also have Jacobson’s organ (or the vomeronasal organ) in their nasal cavity, which opens behind the upper incisors into the roof of their mouths.

Jacobson’s organ is a second olfactory system that is designed for chemical communication. The nerves in this organ lead directly to the brain and they respond to the “undetectable” odors of the world, i.e. pheromones.

In the dog world, the combined sniffing power helps the dog know when others are ready to mate or helps puppies locate their mother when they’re ready to eat. Using the combined power of the nose and Jacobson’s organ, sniffing another dog’s butt tells your dog everything he needs to know about his furry friend.

Humans greet each other by shaking hands, hugging, waving, and offering smiles. We then ask each other how the other one is and other appropriate niceties. Dogs read each other’s body language, but running up and greeting each other by sniffing each other’s butts is the dog version of the human, “Hi! How are ya?”

Dogs that have been separated for a while sniff each other’s butt to confirm the other dog’s identity. All dog’s anal glands have a scent unique to them and it tells other dogs everything about that particular dog. Sniffing the butt tells where the dog has been, what he’s been up to since they saw each other last, what he’s been eating, etc. Just like a human can associate a smell with a memory of a person, dogs use their even stronger sense of smell to identify dogs they haven’t seen in years.

The anal glands of dogs are very potent and serve a definite purpose in the dog world. Most owners don’t realize their dogs secrete a liquid every time they have a bowel movement as it comes out with the stool. This secretion tells other dogs everything they need to know about another dog. Is the other dog healthy? Where has it been? Does it eat a healthy diet? Sniffing another dog’s butt and getting a whiff of their anal glands tells your dog everything he needs to know about another dog.

Dominant dogs are usually the first to start the ritual of butt sniffing when two dogs meet. The submissive dog will often stand very still while this occurs, letting the dominant dog get a good whiff so he knows the submissive dog is not a threat. It’s then the submissive dog’s turn. The dominant dog may growl to end the sniffing session and the submissive dog will stop sniffing and retreat.

Dogs start sniffing each other butts from a young age and it becomes a soothing ritual to them. If your dog is feeling stressed or upset, it will likely sniff some butts to calm down and soothe itself.

Conclusion

Your dog is ready to head home after a fun hour romping through the dog park, playing with friends, and sniffing tons of butts. He’s calm, happy, and completely worn out. A new dog enters as you’re leaving, and they take a moment to sniff each other’s butts in greeting. They prance around for a minute and then you leash up your dog to head back to the car. You and your dog both hold your heads up high as you walk away because you both know that your dog is the ultimate social charmer. After all, he’s a master of butt sniffing.

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Featured Image Credit: Vineyard Perspective, Shutterstock

March 14, 2019

It seems a bit gross, but sniffing butts is how dogs gather information about each other. It’s a normal and important ritual that dogs do during greetings. It helps them to find out things about each other and obtain information that they need to get along and survive.

A butt sniff for dogs is a bit like a hand shake for humans but with far more information received.

The hormones in the glands around the rear end of your dog send out a lot of information that dogs need to understand their place in the world. They also have a special part of their noses called the Jacobson’s Organ that lets them ignore the smell of poop (I want one) so they can smell the glands that release the chemicals they need to smell.

A dog’s nose is far more sensitive than ours and they are able to smell up to 100,000 times better than humans. They can ascertain a dog’s diet, gender and emotional state. They can also tell whether they have met before, and receive important cues on how they should behave towards each other.

Stopping your dog from smelling other dogs butts is robbing them of their instinctual behavior and can be the reason why dogs become aggressive when meeting other dogs on a leash as they aren’t able to ascertain their status with the other dog. Allowing them to sniff each other’s butt is a much more polite way for dogs to greet each other, rather than face to face.

Next time you’re tempted to stop your dog greeting another by sniffing their butt, remember that doing so could create additional stress when meeting other dogs in the future.