Butt Sniffing With Dogs: What It Means

Written by Sharon Parry
Published: May 15, 2022
Image Credit Marek Rybar/Shutterstock.com
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You may say ‘Hey’ and smile when you pass another person on the sidewalk but if you both have dogs, they will greet each other in a much more intimate way. All dogs sniff each other’s butts at some point.  But why do dogs sniff butts and should you just let them get on with it or should you intervene?

It’s all to do with your dog’s highly tuned sense of smell. It’s also connected with the ways in which they communicate with each other. This is nothing like human communication. So it is not surprising that some owners get a little freaked out by it. Here’s the detail on why dogs sniff each other’s butts.

Dogs Can Smell More Than You Can!

Before we answer ‘why do dogs sniff butts’ we need to examine why dogs sniff anything at all and why smell is so important to them. Dogs have the same five senses as we humans (smell, taste, hearing, sight, and touch) but use them in different ways. We like to smell nice odors (like perfumes) and we can detect bad odors (like fox poop). However, we are far more reliant on our sight and hearing to tell us about the world around us. Dogs are different. Their sense of smell is their main source of information about their surroundings. It is about 100,000 times more sensitive than a human’s. Also, their nose contains 150 million olfactory receptors compared to our 5 million. Also, an amazing 30% of a dog’s brain is dedicated to processing odors compared to 5% of the human brain.

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This means that sniffing is a huge part of a dog’s life. So it is not surprising that they need to find out what other dogs smell like when they meet them. It may look like butt-sniffing to you but it’s like us reading a social media bio!

Dogs Have a Communication ‘Smell Organ’

Did you know that dogs have an extra organ that they use just for interpreting chemicals left by other dogs? It’s called the Jacobson’s organ but the scientific name is a vomeronasal organ. Dogs use it for ‘chemical communication’. The Jacobson’s organ is located between the nasal cavity and the roof of the mouth. It opens into both areas and nerves leading directly to the brain. When dogs are using their Jacobson’s organ, they curl their lips, flare their nostrils, pant, and lap.

This is not the same as the system they use for smelling – it does not respond to ordinary smells and uses a different network of nerves. Instead, it is programmed to detect certain chemicals produced by other dogs (pheromones) and a lot of them are connected with mating and reproduction.

So, by sniffing another dog’s butt they are primarily using their Jacobson’s organ to discover if the other dog is ready to mate or not.

why do dogs sniff butts
French bulldog and beagle greet each other by sniffing butts at the park.

Spiky and I/Shutterstock.com

It’s a Type of Greeting

When you meet another human, you are constantly assessing them as you greet them. Dogs are no different. Butt sniffing is the human equivalent of saying ‘Hi, how are you?’ It is a social convention for dogs that have developed over thousands of years of evolution.

We may find it a bit embarrassing and amusing but it is a highly effective way of recognizing dogs that they have already met. Research has shown that dogs from the same family can recognize each other in this way even if they have been apart for some time. It will even give dogs an idea about what their relative has been eating and doing since they last met!

Identification and Information

Obviously, your pooch wants to know who they are dealing with when they meet another dog on the street. They don’t use facial expressions and words, but they do assess body language by circling each other and looking at each other’s movements and positions.

They can also tell a lot about each other from the smell. The chemicals given off by a dog tell another dog a lot about their age, gender and mood. It even indicates what they have been eating, if they are healthy and what the dog has been doing. It’s also a great way for dogs that have not seen each other for a while to confirm that they have actually met before.

To glean all this information, a quick sniff is not enough. What’s needed is a detailed sniff of the butt!

Dog Butts Hold All the Information

So, now we understand why dogs like to take a long sniff of each other. But does it really have to be the butt? Well, actually yes it does!

The reasons for this are a bit gross. Just inside your dog’s butt hole, there are two small sacs which are called anal glands. Your dog may have needed these emptying by the vet if they have been scooting.

When your dog takes a poop, these glands release a disgusting-smelling liquid. You will not normally notice this because the poop smells pretty bad too and you can’t tell the difference.  To a dog, however, there is a huge difference. The liquid that comes out of the anal glands is packed with the chemical messages that your dog’s nose is set up to detect and interpret. Basically, a dog’s butt is where all the information is so that is the obvious place to sniff.

why do dogs sniff butts
When two dogs meet, there is a whole ritual in greeting each other.

iStock.com/Jevtic

It Establishes Dominance

Dogs need to establish who is the boss in most of their encounters and this starts as soon as they spot another dog. The one that starts the sniffing is dominant. This sets the foundations for the rest of their relationship – even if that only lasts for 30 seconds.

You will usually see the submissive dog standing very still and patiently waiting its turn. Once the dominant dog has finished, the submissive dog gets a turn, but this is often cut short with a growl from the dominant dog.

Some dogs are quite secretive and don’t want to let others know anything about them. They sit down and hold their tails over their anus so another dog cannot get a good sniff.

A Soothing Mechanism

For reasons that we humans may never understand, the act of sniffing another dog’s butt is a calming experience for a dog. Many use it as a stress reliever and you may notice that your dog is calmer after they have done it.

You may also notice that your dog is more likely to indulge in this behavior when they are stressed about something. If you notice that your pooch is particularly stressed it is wise to get to the bottom of what is causing it. You could also try some calming treats.

Should you let your dog sniff butts?

This depends on your dog and the situation that you are in. Provided both dogs are healthy and are used to meeting other dogs in a polite and controlled way, there is nothing wrong with it. Butt sniffing is perfectly normal behavior for dogs and can help to prevent confrontation. If supervised dogs are allowed to sniff around each other for a while, they get to know each other and are less suspicious.

However, it is important that you supervise them closely. Look for signs that one dog is getting a bit too over-enthusiastic with the sniffing or that the other dog is feeling uncomfortable. If this happens, it’s time for a quick pull on the leash to make sure that the dogs go their separate ways.

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why do dogs sniff butts
Two dogs gently sniffing and greeting each other in an autumn meadow.
Marek Rybar/Shutterstock.com
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About the Author

Sharon has a Ph.D. in Public Health but has spent the last decade researching and writing about all things connected with animal health and well being. As a life-long animal lover, she now shares her family home with three rabbits, a Syrian hamster, and a very energetic Cocker Spaniel but in the past she has also been a Mom to Guinea Pigs and several cats!She has a passion for researching accurate and credible information about pets and reviewing products that make pet owners' lives a bit easier. When she isn't checking out new pet products she's trekking around the Welsh mountains and beaches with her dog - although she lets her husband and her three grown up daughters tag along sometimes if they are lucky!

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