Why Does My Dog’s Butt Smell Fishy?

Veterinarian pinching his nose as a reaction to a dog patient's smelly anal glands who is sitting in front of him

Why does my dog’s butt smell like fish, and how can I make it not smell that way? It’s not an uncommon question for pet parents, and these unpleasant smells often get chalked up to ‘normal’ dog odors. But there’s a reason why your dog’s butt smells like fish, and it has to do with their anatomy. 

Before we get to our best odor-eliminating tricks, we’ll discuss why dogs end up smelling like fish in the first place–and how you can help prevent those unpleasant scents long-term. 

How anal glands function

That fishy smell is from the scent-marking secretions that originate in your dog’s anal glands. So what are the anal glands, and are they supposed to smell like fish?

First, both dogs and cats have two small anal glands. They sit low on either side of the anal cavity at the 4 and 8 o’clock positions and can range from pea to grape size depending on the animal. Anal glands aren’t visible from the outside but can be carefully accessed by your veterinarian or someone trained in anal gland expression.

What’s the function of anal glands? The anal glands–also called anal sacs–are considered scent glands. When you see two dogs sniffing each other’s butt in greeting, they’re downloading information from the scent glands. They’re learning their furry friend’s age, sex, and overall health status–all with a few whiffs!

Tiny sebaceous (sweat) glands line the inside of your pet’s anal glands and produce an oily fluid that smells like fish. These smelly excretions produced by dog anal glands are useful for identification, but they need to express regularly to keep anal glands functioning properly.

Why does my dog’s butt smell like fish?

Now that you know how anal glands work, you might be wondering: how stinky is too stinky? Should you expect certain unpleasant smells, or is a persistent fishy smell a sign of something amiss? Let’s break down the basics. 

1. Their anal glands expressed during defecation

First, it’s important to note that the scent/anal glands should naturally empty with every bowel movement. Have you ever wondered why dogs sniff each other’s poop? That’s to investigate the anal gland secretions that coat the stool and give them information on another dog. 

This is the most natural way for glands to empty, and also means that your dog shouldn’t be smelling too fishy–because the stinky fluid has exited the body. If any fluid remains around their anus after defecation, it could leave a trace of fishy odor.

2. They excreted or “expressed” under duress

Sometimes, when dogs are scared, their anal glands will automatically express and they’ll immediately smell like fish. Much like cats will spray when nervous to mark their territory, dogs will involuntarily express to mark their territory in a new or stressful environment. That's because the glands are located between the internal and external anal sphincter muscles, and when they get scared they may inadvertently tense up, releasing the contents of their anal glands.

3. Their anal glands are full

The final reason why a dog’s butt smells like fish is when their anal glands aren’t emptying properly. As we mentioned before, your dog’s anal glands should empty naturally with every bowel movement–if they don’t, the fluid may slowly leak out on its own. This can happen between bowel movements when your dog is at rest, leading to a slew of unpleasant smells and messes around the house.

Pug dog sitting in metal tub basin for a bath

How to deodorize your dog’s butt 

So your dog has a stinky butt. How do you get rid of the smell? Aside from supporting proper anal gland health–we’ll get to that, next–you can neutralize unpleasant odors pretty effectively at home. 

Give their bottom a wipe-down 

Pet cleaning wipes are a lifesaver for any pet parent, but anal gland wipes are a game-changer for this especially odorous area. If you do anal gland expressions at home or if you notice leaking or oozing from the anus–or if your dog’s bum simply needs a refresh–try a pet cleaning wipe. 

Use a spray deodorizer

Take a hands-off approach to stinky butts with a deodorizing and anti-itch spray. If your dog is struggling with painful swelling around the anus, look for an anal gland spray with Lidocaine for pain relief and Hydrocortisone for anti-inflammatory support. 

Shampoo when needed

If fishy smells are persistent or your dog has dense fur around the anus, a thorough shampoo might be the best way to erase odor. Choose a shampoo that’s gentle on delicate tissue, which is especially important for dogs with a strong fishy smell–who probably have tenderness due to underlying anal gland issues.

Supporting anal glands to reduce fishy smells

While you can deodorize your dog’s butt to the high heavens, addressing the underlying issue is paramount for reducing odor in the future. Healthy anal glands won’t give off extreme odors, and proper function can be supported in several ways at home.

Feed them a fiber-rich diet

Fiber helps to bulk up and firm your dog’s stool, which makes it more effective at expressing the anal glands as it passes through the anal cavity. Fiber-rich ingredients that are safe for dogs include Pumpkin, Milled Flaxseed, Apple, and Wheatgerm. A daily fiber supplement can be hugely beneficial for dogs struggling with leaky or stinky anal glands.

Work on hydration

Without hydration, fiber supplements and digestion won’t reach their full potential. Keeping your dog hydrated with fresh, clean water or moisture-rich foods can help them pass more productive stools and support natural anal gland expression.

Improve digestion

Giving your dog probiotics, prebiotics, and digestive enzymes can be especially helpful if your dog is sick or experiencing changes in digestion. Diarrhea is one of the most common reasons for anal glands not emptying naturally because the stool isn’t bulky enough to express the glands. Supporting your dog’s fiber intake and digestive function can be just as essential for anal gland health.


Fishy smells aren’t exactly abnormal, but it’s important to note how smelly and how frequently your dog is stinky. By supporting your dog’s overall anal gland health, you’ll also be setting them up for better hygiene and a fresher scent–while saving your nose!