6 Reasons Why Your Dog's Breath Smells Like Fish

Author: K. Marie Altoby K Marie Alto Updated 10 min read

6 Reasons Why Your Dog's Breath Smells Like Fish

We love our furry friends, but sometimes they just carry odors with them that make your eyes 😰 water.

I've talked about one of these smells before in my post about "Frito foot," but I don’t think anyone would argue that a corn chip smell is as bad as fish!

We usually associate fish 🐟 with cats, who just love to try and catch your pet fish, but did you know that dogs are actually way more likely to smell like fish than their feline counterparts?

There are a few big reasons why your dog’s breath smells like fish🐟. In today's post, I discuss them in order, from the most trivial and obvious to the most uncommon.

So let's go through them!

#1: Your Dog's Breath Smells Like Fish Because You Feed Them Fish

The first possible cause of your canine companion's breath smelling like fish is that you've fed them fish.

Sounds too simple to be true, right? Well, turns out it's a relatively common (and harmless, except to your nose) cause of fishy odors.

A Dog Eating Fish Image by Toe Beans

On the one hand, maybe you're feeding them fish, and just don't expect the odor to linger hours or days later. More likely, though, you're giving them some kind of food that has fish as a core ingredient.

It might not smell like fish when it's in a dry kibble form, but once it's re-hydrated in the digestive system of your fur baby, well, that's when things get out of hand.

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Fishy breath can also happen if you're giving your fur baby fish oil supplements. Fish oil is a great way to help promote better health, and it gives your pup plenty of tasty Omega 3s.

Many fish oil capsules promote "no fishy odor," but that's more for people who swallow them and don't worry about them again. However, dogs might chew on them, which could cause them to burp up some of the odor.

If your fur baby hasn't had any sort of a dietary change recently, but you're smelling fish a lot more often, there may be something else going on.

If you suspect food to be the culprit, try slowly changing your pup’s diet to an alternative food to see if the fishy smells go away.

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If it does, the problem is solved; you can enjoy more puppy kisses without worrying about smelling like the fish markets on a hot summer day when you're done.

In general, keep in mind that not all fish are created equal. And that there are some fish that are safer than others.

According to Dr. Lesley Gillette, DVM at PetMed, the types of fish that are safe for dogs include:

“Whitefish, flounder, salmon, herring, catfish, cod, whiting, light tuna fish (canned). These fish are generally less likely to have high tissue mercury levels or significant parasite burdens.”

#2: Your Dog's Breath Smells Like Fish Because They're Eating Something Gross

We’ve all met a pup that absolutely loves eating whatever they can get their lips around. Everything!

Their food, their toys, a stray leaf, some rain-soaked cardboard, something positively rancid in the trash, a pile of droppings from the local wildlife; it doesn't matter what it is. As long as it smells tasty – to them – they're going to try to eat it. Does this sound like your pup?

Unfortunately, a lot of different kinds of garbage, when they rot and ferment and generally turn into gross slime, end up smelling somewhat like fish.

Dogs Eating Trash Image by Toe Beans

Okay, that's not quite true. It's not the actual trash itself that smells like fish; it's the bacteria that builds up in your fur baby's mouth.

In people, when bacteria starts to build up on our teeth, we call it dental plaque, tartar, or bad breath caused by halitosis. In dogs, we call it, "Oh, gross, Rex, stop it! Eww!"

Dogs don't have hands, and their eyesight isn't really as good as ours. They interact with the world through their noses and their mouths. That's why they seem absolutely determined to sniff and taste everything they can; it's how they experience the world!

That doesn't really make it any more pleasant when we're on the receiving end of fishy kisses, though. Luckily, bad breath caused by eating gross garbage isn't really a bad problem.

It's nasty, sure, and it's perfectly capable of stinking up a room. Then again, any dog parent knows just how many different ways a dog has to smell up a room (and clear it out), so that should come as no surprise.

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If your fur baby has bad breath through their diet – either because of what you're feeding them or what they're eating when you aren't looking – it's pretty easy to handle.

One thing you can try is giving them a "dental treat." Dental treats are treats that are made up of ingredients that can scour bacteria from their teeth while they chew. Commercial options are available, but you can also make a homemade treat by making "bad breath cookies."

Here's what you'll need:

  • Three cups of oats
  • One cup of parsley
  • One cup of grated carrots
  • One mashed banana
  • ½ cup of plain yogurt
  • One tablespoon of coconut oil

Toss the oats in a food processor and blitz them until they're floury, and then melt the coconut oil. Mix the oil, yogurt, banana, carrot, and parsley in a bowl, then add the oats to make a kind of coarse dough.

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Scoop out balls of this mixture, roll them, flatten them, and arrange them on a cookie sheet. Bake them for about 25 minutes at 325 degrees (F), then remove them and let them cool.

You'll be left with a sort of cookie that helps cut down on mouth bacteria, smooths out digestion, and generally improves the overall odors of your fur baby while still being a healthy snack. Why not give it a try? It's super easy to make.

You can also just brush your dog's teeth. You should be doing that anyway, though, for reasons I'm about to get into.

#3: Your Dog's Breath Smells Like Fish Because They Have Tooth Issues

"Plaque builds up on teeth within 12 hours of cleaning, therefore brushing your pet’s teeth at least once daily, for just 60 seconds, is the best and most effective method to decrease bacteria in the mouth.” - Bethany Wright, LVT Cornell University College of Veterinary Medicine’s Dentistry and Oral Surgery

Dog Showing Teeth Image by Toe Beans

Bacteria building up is obviously going to smell bad, and usually it’s a fish-like odor. Unfortunately, it's probably the #1 reason why dogs end up with fishy breath. Why do I say "unfortunately"?

Well, the reason is that bacteria building up can have a lot of different causes, and most of them are a lot worse than just plaque building up on their teeth.

The first cause is periodontal disease or gum disease like gingivitis. When bacteria build up on the teeth, it forms plaque, which can harden into tartar, which can cause gum irritation and tooth decay. This alone can smell pretty bad, but it can lead to worse issues as well.

If it is left unimpeded, tooth decay can result in cavities and bleeding - even abscesses. An abscess is an infection, usually in the gums or the root of the tooth.

It's basically a pocket full of bacteria and infected tissue, and it requires antibiotics and dental treatment to care for. Humans get these, too, and our treatment is either pulling the tooth or getting a root canal.

There are no root canals on dogs, so your vet will likely just recommend that the tooth be pulled. After a course of antibiotics, of course.

The worst part of this isn't the smell, though; it's the pain. Tooth infections hurt! Nobody wants to see their precious fur baby suffer, so it’s important to stay on top of brushing their teeth and caring for their oral health.

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Another possible cause of oral issues is ulcers. Ulcers are like cold sores, exposed bits of inflamed gums or cheeks, where a mild infection and pain lingers.

These happen when your fur baby eats something caustic like lye, laundry soap, or essential oils. Sometimes, they can be caused by more serious reasons.

"There are a variety of different health issues that can lead to the formation of mouth ulcers. If any of these problems go untreated, it could lead to serious health problems for your pup. Some of the most common causes of mouth ulcers in dogs include periodontal disease, plaque and tartar buildup, folds in the facial skin, tumors, kidney disease, gingival hyperplasia…" - Montana Pet Dental

Luckily, while they're painful, when discovered early, they can all be treated successfully by your vet.

#4: Your Dog's Breath Smells Like Fish Because of Anal Gland Expression

Now, let's talk about one of the grossest reasons why your canine kiddo is having some fishy breath issues. Brace yourself because this one can be disgusting to think about.

Dog Sniffing Other Dog's Rear Image by Toe Beans

So, you know how your dog doesn't have hands? And how, when they have something stuck between their toes or worked into their fur, they'll lick and nibble at it to work it out? And how can they do the same thing for itches and other irritations?

Well, one source of irritation is something called the anal glands. These glands sit on either side of the anus, below the tail, and they produce a pungent odor. This odor, to us, smells very fishy. To dogs, though, it's a cornucopia of varied smells, unique to each dog.

The purpose of this scent is to mark territory and serve as a sort of unique identifier for each canine. That's why dogs, when they meet and greet each other, will often do that little butt sniff we all find so off-putting and amusing.

Well, those anal glands don't stop producing their scent just because your fur baby is settled in the home and has no need to mark territory.

They need to "be expressed," which means emptying them of the gross-smelling liquid inside them. Usually, they can do this when they go to the bathroom, but sometimes the anal sacs get a little clogged.

Pet Blog by Toe Beans

Well, your fur baby doesn't have hands, so the only way they have to handle this issue is, you guessed it: their mouth. When they're cleaning themselves, they may do a little licking and nibbling to express those glands.

Now, here's the gross part: that fishy smell on their breath is that liquid, lingering. Try not to think too hard about that next time you're getting some fishy dog kisses.

By the way, on the subject of anal glands expression, if you are one of those pet parents that pays for having your pup’s anal glands expressed every time you go to the groomers, make sure to watch the short educational video by Dr. Brian Evans at Coastal Animal Hospital for some useful advice.

Stop Expressing Anal Glands – 2:50 min Video

#5: Your Dog's Breath Smells Like Fish Because They Have an Infection

Above, I mentioned that bacteria cause that fishy smell and that it's usually because of an oral infection like gingivitis or an abscess.

That's only partially true. Infections cause fishy breath, but it's not always a tooth or mouth infection.

Vet Examining Dog Teeth Image by Toe Beans

In fact, if your fur baby has a fishy smell and you can't find anything wrong in their mouth, it may be a sign you need to take them to the vet right away.

That's because other kinds of infections can cause that fishy smell. These include kidney infections, respiratory infections, sinus infections, or gastrointestinal infections.

Any time there's a nasty little microbe running wild in your fur baby's body, there's a chance that it's because of an underlying infection.

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Now, I'm not saying that every hint of fishy breath is a sign that your fur baby needs a run to the emergency vet. If a new fishy smell appears, or is getting much worse, keep an eye on their other behaviors.

Are they eating right? Are they vomiting? Are they having issues with urination, going too frequently, or not frequently enough? Do they seem unusually tired? Are they sneezing, drooling, or sniffling more than normal? All of these can be signs of something underlying that needs to be treated.

Dog Brushes_V2_ by Toe Beans

If you're concerned, you can also give your vet a call and see if they can walk you through a set of questions to determine if there's a problem that needs attention.

#6: Your Dog's Breath Smells Like Fish Because They Have Organ Problems

I'm putting this one at the end of the list because it's generally the least common cause of fishy smells. It is, unfortunately, the most dangerous of them, too.

Vet Examining a Dog Image by Toe Beans

As discussed in point #3 above, there are several conditions that can cause bad breath, which can be fishy, or it can be foul in other ways.

  • Diabetes, which leads to higher blood sugar (usually) and can cause fruity or sweet-smelling bad breath.
  • Kidney disease, which can lead to a build-up of uric acid in the blood, which in turn affects breath and makes it smell bad.
  • Liver disease. The liver filters toxins out of the body (in both people and dogs), so when it starts to fail or just not function as well, those toxins can build up and cause all kinds of problems, including bad breath.
  • Some cancers can cause dysfunction in the organs, which can lead to all kinds of problems, including bad breath.

Don't worry too much about these conditions quite yet:

If you suspect that your dog has any of these conditions or if their symptoms worsen, you should always take them to your veterinarian. Don't try to diagnose these conditions yourself!

Some of these can manifest with mouth ulcers. Now, I'm not saying that if your fur baby's breath smells like fish, they're suffering from organ failure.

It's way, way, way more likely that they just ate something foul from the garbage, or that their anal glands need to be expressed, or even that they just need to have their teeth cared for.

But, if bad breath is accompanied by other issues, you may need to start looking for an underlying cause.

What do you think? Does your fur baby have fishy breath on the regular? What have you found that can help take care of it? Let me know in the comments below!

Additionally, if you are feeling like getting a little special something for your fur baby that is unique, made right here in the USA, 100% pup and cat safe, USDA certified organic and brought to you by a US company, check out Toe Beans online pet supplies store!

As always, if you found this content useful, all blog posts on Toe Beans are social media shareable. So, what are you waiting for to spread the love? Go ahead and hit any social media icon of your preference around the post for instant sharing with friends and family. Sharing is caring!

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K Marie Alto
K Marie Alto

K. Marie is an animal lover, wife, kitty mom, dog auntie, writer, and co-founder of Toe Beans, a proud American family-owned online boutique pet supplies store focused on the improvement of the life of furry family members via pet parent education, better products, and advocacy. She has over 20 years of experience as a pet momma. She loves sharing her personal journey and experience as a pet parent via her blog and Facebook page where she currently has more than 50K followers (@furrytoebeans) and counting :-). Read more

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