Why Does my Dog’s Breath Smell Like Fish? (reasons & remedies)

Last Updated: April 27, 2023

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dog with open mouth that smells like fish

Everyone is familiar with "dog breath." It's that distinct and natural odor that comes from your pup's mouth. No matter how hard you try, there's no way to permanently get rid of dog breath.

While breath freshening treats and water additives certainly do their part to provide some temporary relief, natural dog breath is something you're just going to have to live with. Canines explore the world with their tongues, so bad smells are to be expected.

But what if that smell reaches a whole new level of awful?

If you have ever been taken aback by a pungent fishy odor accompanying your dog's kisses, you're not alone. Most owners experience that distinct fish smell at some point. It's not something that usually goes unnoticed.

The smell is dramatically different than typical dog breath, so it's definitely a cause for concern. But what causes this smell?

Here are some common reasons why this smell occurs and what you can do to treat it.

#1. Fishy Breath from Something Your Dog Ate

When you notice a sudden wave of bad breath, your first instinct may be to figure out what your dog ate. Often times, the solution is to simply keep your pup out of trash or away from any other disgusting item that is tempting them to take a taste.


Unfortunately, eating animal excrement is an all-too-real thing that many dog owners have to deal with. It's a fairly common habit that's most prevalent among young puppies. However, puppies can continue to eat poop long after they have reached adulthood.

The type of poop dogs will eat is usually not limited to a specific animal. As a result, it's not difficult for dogs to access.

Take a quick look around your backyard and you'll probably find some droppings from birds, squirrels, and rodents. If you live in an urban environment, you also have to deal with droppings from other dogs.

There is no consensus as to why dogs choose to do this. Most owners simply look the other way and scold their pooch. That is, however, until it starts to cause some major bad breath.

Obviously, eating something that smells as awful as feces is going to result in some lingering odor.

Depending on how much your dog was able to consume, they may also have little bits and pieces in their teeth or gums as well.

How to Remedy the Problem

Aside from keeping your dog away from poop as much as possible, your best bet to solve this issue would be to get help from a canine behavioralist. They may be able to train your dog to avoid eating poop.

It's important that you don't ignore the problem and let your pup do what he or she wants. Eating feces puts your dog at major risk for parasitic infections and disease.

#2. Poison

dog with fishy breath in open mouth

A suspiciously fishy smell emanating from your dog's mouth may also be a sign that your dog needs immediate medical attention. They may have gotten into some poison.

Certain pest poisons contain chemical compounds that produce a fish-like smell when mixed with your dog's saliva. 

Compounds like phosphorus or zinc phosphide are typically used to eradicate rat populations around the home.

Rat poison is very common and readily available at most home stores. While you may not have it in your home, one of your neighbors might.

Seek Immediate Veterinary Care

To solve this problem, you need to take your dog to an emergency vet as soon as possible. These poisons are more than capable of killing your dog. The outcome will depend entirely on how soon you can get it out of your dog's system. 

Your vet may ingest vomiting and perform a number of other procedures to minimize the effects of the poison. If it's possible, take a small sample of the poison with you. This will help the vet determine how much danger your dog is in.

It's important to keep any type of poison out of reach so that your dog can remain safe at all times. 

You should also make sure that your dog is properly contained when they're outside so that they can't get into anyone else's poison supply.

#3. Dog Food Formula

That's right, your dog's very own kibble may be the odor-causing culprit! Fish is a very common ingredient in many commercially available dog foods.

It's relatively cheap, provides plenty of protein, and is chock-full of omega fatty acids that benefit your dog's skin. 

Typically, recipes that contain fish also have other protein ingredients. Thus, the smell is masked. However, in higher concentrations, you may find that the smell lingers a bit. More often than not, that smell will fade within a few hours as your dog's mouth regulates itself.

Possible Remedy

If the fish smell is unbearable, you can always switch to a recipe that has no fish in it at all. Alternatively, you can look for formulas that have less fish in them.

Check the ingredient's list and look out for pure fish ingredients. These include salmon, mackerel, and a host of other fish species.

Also, look out for fish meal and fish oil. It's not recommended that you get rid of all fish-based ingredients. Remember, omega fatty acids are beneficial and can do a lot to improve your dog's overall health.

#4. The Dreaded Anal Gland Issue

Many dogs suffer from anal gland problems. It's not a pretty thing to deal with, but resolving these problems can provide immediate relief for your pup and get rid of any lingering smells.

You see, all dogs have two anal glands around the anus. Every single time your dog goes out to use the bathroom, these glands should be expressed. Their contents are excreted along with feces. The contents of the glands have a very pungent fish-like smell.

Unfortunately, dogs aren't always able to express the glands on their own. This is common with smaller breeds. When they aren't expressed, they continue to fill.

Eventually, they become swollen and very painful. You may see your dog scooting their bottom on the floor or trying to bite their behind in an attempt to express the glands manually. 

In most cases, they aren't successful. However, the fluid in the glands may start to leak out. When your pup licks at the glands, the wretched smell goes along with it, resulting in bad breath.

Expressing the Anal Glands

To solve this problem, your dog's anal glands will need to be expressed manually. This can be done by your veterinarian. Many dog groomers can also perform the task.

However, if your dog has regular anal gland issues, you may want to learn how to do the job yourself. It's best performed outside or in the tub.

It should be done immediately before a bath so that you can clean up any messes and get rid of the smell as soon as possible. 

With a gloved hand, simply lift your dog's tail and squeeze the glands. This is a very simple process. Your vet can provide you with more in-depth information and show you the proper technique to be effective.

#5. Odor-Causing Dental Problems

Bad breath, also known as Halitosis, is most often caused by dental issues. Dogs are susceptible to tooth problems just like us humans. However, they typically don't receive deep cleanings on a daily basis as we do. 

Unfortunately, this can lead to potentially painful dental dilemmas that have the undesirable side-effect of bad breath.


Gingivitis is directly caused by the buildup of plaque on your dog's teeth. Your pup's mouth is teeming with bacteria. Over time, a thin film of gunk will accumulate on the surface of the teeth.

If left untreated, this plaque will harden, resulting in gingivitis. The teeth can then start to separate from the gums, providing all kinds of hiding places for food and bacteria.

One tell-tale sign of gingivitis is red and swollen gums. Odor can be caused by the bacteria itself or tiny food particles that are caught in the gumline.

What You Can Do To Stop It

The best thing you can do is to brush your dog's teeth regularly. Ideally, you should brush your dog's teeth a couple of times a week and utilize other dental products that can combat plaque buildup.

Dental chews and rawhides are a great solution. The natural chewing motion will clean your dog's teeth through abrasion alone. Water additives, gels, and wipes are also available.

As long as you keep up with your dog's dental health, you can treat this issue and prevent it from turning into periodontal disease.

Periodontal Disease

Periodontal disease is one of the most serious dental problems. It's also one of the most common. It's estimated that up to 80 percent of dogs suffer from periodontal disease at some point in their life.

At this point, gingivitis has progressed and the bacteria in your dog's mouth is wreaking havoc on their teeth at their roots. Bacterial infections cause a strong fish smell, even after you brush their teeth.

If you ignore this problem, your dog can start to lose teeth pretty quickly. The disease can also cause issues with other organs in their body.

Treating Periodontal Disease

If you suspect that your dog has periodontal disease, you need to take them to a veterinarian as soon as possible. Your dog will need to undergo a deep tooth cleaning.

This procedure is similar to standard annual cleanings. However, the hard plaque that has accumulated on the teeth is scaled off. 

The veterinarian may also use specialized tools to reach down deep to the root of the tooth. If there are any teeth that have lost their grip on the bone, they can be removed to provide your pup with relief and get rid of the awful smell.


Abscesses are often associated with periodontal disease. Essentially, the bacterial infection has made its way down to the root of the tooth. This is where all the nerves are, so it's an incredibly painful issue for your pup.

You may notice that they avoid food or paw at their mouth in an attempt to find relief. A small pocket of pus will start to develop over time. Depending on the severity of the abscess, the tooth may start to ooze a very pungent liquid.

Abscess Remedy

Like periodontal disease, a tooth abscess requires professional assistance. Your vet will be able to remove the tooth, drain the abscess, and clean up any other dental problems your dog is suffering from.

All of this is done under sedation so that your vet can do all they need to do without issues.

After your dog has recovered, the smell will be gone. Then, it's all about being proactive about your pup's dental health to avoid further problems.

Health Issues Linked to Bad Breath

Noticeably bad breath may also be a sign that your dog is suffering from a medical condition. Oftentimes, problems with certain organs will affect the environment in your pup's mouth. This results in a change in smell.

- Kidney Failure

Kidney and liver disease have a host of symptoms. One of them is bad breath. These two organs play a crucial role in your dog's overall health. They filter out toxins and affect how your dog processes the things that go into their body.

When you start to notice a bad fishy smell coming out of their mouth, it may be a sign that they're at the later stages of kidney disease. Other symptoms may include lethargy, vomiting, dehydration, and weight loss.

What You Need to Do

You should seek veterinary assistance as soon as possible. Not only will they be able to diagnose the problem, but they may also help to determine the next course of action.

The treatment options will vary based on your dog's particular symptoms.

In many cases, kidney disease can be managed with a low-phosphorus diet. This may help to get rid of the bad smell while ensuring that your dog stays healthy.

- Sinus Infections

Sinus infections, such as rhinitis and sinusitis, can cause bad breath in your dog due to their biological makeup. Like with humans, the sinuses are closely connected to the throat.

When your dog's sinuses are irritated, whether it's through infection of the mucous membrane or general inflammation, the sinuses produce a lot of fluid. This fluid is pretty foul in terms of smell.

When it slides down your dog's throat and into their digestion system, it will affect their breath as well.

How to Treat a Sinus Infection

Luckily, sinus infections are relatively easy to treat with some medications. Your vet will be able to find one that works for your pup. They'll also perform a thorough examination to ensure that nothing else is awry.

Sometimes, sinus infections can be caused by tooth and gum issues. By treating the cause of the sinus infection, you can stop the flow of fluids and keep the bad breath at bay.


A bit of bad breath here and there is not something to fret over. There are plenty of minty treats, water additives, and dental chews to keep your dog's breath fresh throughout the day. It's only when smells become severe that you should start to worry.

That awful fishy smell may be a symptom of something more serious. When in doubt, use the fishy breath as a sign and get your dog checked out by a vet.

If there are any serious complications, whether it's organ failure or dental problems, you can address them as soon as possible to bring your dog back up to good health.


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About the author 


Steve is a writer with over 10 years of experience in dog training and nutritiion.

His goal is to educate dog owners about the ins and outs of canine behavior as well as keeping up with the latest scientific research in the field.