Why do dogs smell each other’s butts?

We’ve all seen it: your dog is walking around, minding their own business, when another dog comes up and begins sniffing their butt. It’s something we all write off as a “dog thing”. But what is the science behind it, and why do dogs like to smell each other’s behinds?

While it seems bizarre to us, there’s a deeper reason for this behaviour. Here, we answer “why do dogs smell butts” and explain the reasons for it.

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Why do dogs smell each other’s butts?

Dogs sniff butts as a greeting and to get information. It’s their way of reading into each other’s scent profiles, and since dogs rely on their nose for pretty much everything, it makes sense. You can think of it as a dog’s version of a handshake.

A dog’s sense of smell is far deeper than a human’s. For example, a dog has around 150-220 million olfactory receptors. We only have five million, which means their nose is far more sensitive compared to ours. That gives things like sniffing butts a different dimension for dogs.

Sometimes, the duration of the sniff can indicate dominance, too, or calm a dog down.

The science behind the sniff

So, why do dogs smell other dog's butts? The key behind why dogs sniff each other’s behinds is the Jacobson’s organ, also known as the vomeronasal organ (VNO). This helps dogs pick up and analyse pheromones, and it’s found in the nasal cavity. You can think of it as a dog's secondary scent system.

This organ helps dogs find more detailed chemical information when smelling, like from anal glands. A dog’s anal gland contains all kinds of unique scent markers, allowing other dogs to pick up a lot of details. Their nose can smell compounds and bacteria, which gives a birds-eye sniff of a dog’s health and status.

But why the butt? Why not anywhere else?

Well, a dog’s anal glands naturally empty when they poop which releases an odour. This odour reveals some vital information about dogs; it’s unique to every canine, and it’s strong. Dogs have a strong scent memory, so they use this opportunity to store “data” about the dog and allows them remember each other years down the line.

If they meet again, dogs will sniff each other’s behinds to “update” the information they have on each other. It’s pretty gross, but you can think of it as a dog’s version of big database.

What dogs learn from a butt sniff

By looking into the scent, they can find out another dog’s:

• Age

• Gender

• Health

• Mood

This is efficient for dogs and, as pack animals, they need information quickly.

Is it safe or normal? Understanding canine greetings

The behaviour is definitely normal. You don’t need to worry; it’s something dogs do that we’ll never quite get, and that’s okay.

You don’t need to find it embarrassing - it’s totally natural for dogs. But if you’d like to stop your dog from doing it, make sure you understand their body language cues. You can train them to understand firm commands like “leave it” or “come’ to redirect their attention, too. This is useful if your dog is sniffing other things they shouldn't.

But if your dog shows certain signs around sniffing, like aggression, baring teeth, growling or obsessive behaviours, look into it. Always chat with your vet if you notice behaviour problems with your dog.

What if my dog’s butt smells really bad?

Now, no butt smells nice, does it? But what if your dog’s behind smells especially bad? We don’t want to cause too much panic, but we recommend seeing a vet if your dog’s behind always smells pungent.

It can indicate a health issue like:

• Allergies

• Impacted anal glands

• Infections

• Parasites

• Poor diet leading to stool problems

Key symptoms to look out for alongside the bad smell include:

• Discharge

• Licking

• Pain

• Scooting

• Swelling

But follow your vet’s advice here as they’re the experts. It’s something they’d likely notice during a routine check, too.

Understanding your dog’s social world

Sniffing each other’s butts is just one layer of a dog’s social world we’ll never truly get. But we do know it fits into pack dynamics and dog psychology. Dogs can’t take the risk of not knowing information about another canine.

Since they’re pack animals, they need to move quickly and efficiently when out and about. Sniffing, and smells generally, give dogs less anxiety, promotes positive social interactions and allows them to stay as the alert, empathetic animals we all love.

Now, some dogs won’t be happy with getting sniffed, especially since there’s a dominance element at play. It’s worth taking care when dogs meet each other for the first time. If you know your dog doesn’t respond positively to getting sniffed, we recommend allowing for plenty of space and having greetings on-leash.

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