A dog reaches his snout onto a table to take a bite of cooked fish, potentially causing his breath to smell like fish.

Does Your Dog’s Breath Smell Like Fish?

Have you ever noticed that your dog has bad breath? “Dog breath” is rarely pleasant-smelling, but on some occasions it’s especially foul. Some dog owners have complained that their dog’s breath smells like fish. A fish odor can occur for several reasons and in all types of breeds.

The medical term for bad breath is “halitosis.” Bad breath can be caused by a dog’s diet, ingestion of different foods or trash, mouth or dental disease, disease of the upper respiratory tract, infections, or other metabolic problems, such as diabetes.

Why Does My Dog’s Breath Smell Fishy?

There are dozens of causes of canine bad breath, since it is merely a symptom of a larger issue. For example, breath that smells like fish may be caused by something your dog ate, an ulcer in the mouth, or from a tooth infection. Some of the possible causes of fishy smelling breath are minor and others may point to a serious condition that requires treatment. Whatever the cause, fishy breath makes kisses unpleasant and gives pet parents pause.

5 Oral Problems That Can Cause Fishy Breath in Dogs

Dogs are vulnerable to many of the same oral conditions as humans. One of these may be the reason your dog’s breath smells like fish.

Periodontal Disease

Gingivitis is an inflammation of the gum tissue, which is commonly caused by dental plaque. This results in swelling and redness of the gums as well as bad breath. Plaque develops when the normal bacteria in the mouth mix with proteins and starches found in saliva. This mix produces plaque material that adheres to the teeth. Eventually, plaque turns into tartar, which firmly adheres to the teeth. It is most obvious just below the gum line where it accumulates. While common, periodontal diseases like gingivitis are easy to prevent with routine cleaning, teeth brushing, and dental care.

Tooth Root Abscess

An abscessed tooth in your dog’s mouth can cause bad breath. Some tooth root abscesses are contained within the mouth and others will abscess up through the skin. Owners often take their dogs to the vet to address swelling on the cheek just below the eye. Inspection of this wound or a sedated oral examination can reveal an abscessed tooth. Treatment includes tooth extraction (removal) or root canal procedures. Once the tooth is treated, your vet will likely prescribe antibiotics and pain medication depending on the severity of the infection. Remember to have your dog’s teeth examined and cleaned regularly. Oral hygiene is essential for avoiding bad breath and more serious concerns.

Oral Ulcerations

Ulcers in the mouth can result from infection, reactions to certain drugs, or from ingesting or licking caustic substances. Common household caustic substances may include the following:

Oral Infections

Oral tissue can be traumatized and infected by burns or from trauma resulting from chewing on bones, sticks, and other sharp objects. Another cause of oral tissue trauma is from bite wounds from fights with other animals.

Oral Tumors

Tumors in the mouth can become infected or parts of the tumor can begin to die. With time, this can lead to a foul, fishy odor. Among the most common types of oral tumors are dental epulides. These can vary in appearance, but they’re all unsightly.

Is It Something Your Dog Ate?

It’s possible the fish-like smell is the result of something your dog ingested or got stuck in their mouth. The culprit may surprise you. In addition to actual fish, any of the following could be the cause of your dog’s disgusting breath:

Foreign Materials

Dogs aren’t exactly the pickiest eaters. Occasionally pieces of bone, sticks, and clumps of hair get into the mix. These can become stuck in the mouth and the resulting bacteria buildup can cause fishy or otherwise nasty breath. Even a healthy dog can fall prey.

Other Dietary Mishaps

Certain pets will eat just about anything in the world. Other malodorous things that may make it into your dog’s mouth or digestive tract include everything from dead animals, garbage, animal feces, compost, spoiled food, or any object they find on the ground. All of these may result in halitosis.

Pet parents can prevent inadvertent ingestion by always keeping a close eye on their dogs and taking action when necessary.

6 More Potential Causes of Fishy Breath in Dogs

Sometimes bad breath doesn’t have its origin in the mouth. These underlying conditions could also be to blame:

Digestive Problems

Some dogs with stomach or digestive problems including gastroesophageal reflux, stomach ulcers, and hemorrhagic gastroenteritis can have bad breath. Vomiting can also result in foul smelling breath.


Cancer of the throat, mouth, lungs, and nose can all cause foul breath.

Respiratory Infections

Various infections of the respiratory tract can cause foul smelling breath. It can be especially noticeable during exhalation or coughing.

Kidney Diseases

A decline in kidney function can cause some dog’s breath to have the odor of ammonia or urine.


Another disease that can cause an abnormal oral odor is diabetes. A severe form of uncontrolled diabetes, diabetic ketoacidosis, can cause an abnormal sweet, fruity odor.

Liver Disease

Liver dysfunction can result in a sweet, musty breath, which is caused by dimethyl sulfide accumulation.

Your dog will likely require serious medical intervention if their bad breath is the result of a serious underlying health condition like these.

How to Make Your Dog’s Fishy Breath Go Away

To make your dog’s bad breath go away, you first need to identify the underlying cause. Often, you can identify the cause of your dog’s bad breath by asking the following questions:

Why Does Your Dog’s Breath Smell Fishy?

Even after asking these questions, it can be difficult to know what’s behind your dog’s sudden halitosis. Reach out to your veterinarian for additional support if the issue persists.

Are You Sure It’s Their Breath?

Your dog’s fishy odor may not be coming from its mouth at all. In fact, the problem might be the result of issues on the other end of your dog’s body. Secretions from your dog’s anal sacs may be causing the unpleasant scent.

What Are Anal Sacs?

Anal glands are two sacs located on either sides of your dog’s anus. These glands release scent markers, most notably in feces. That’s why your dog is so interested in smelling other dog’s butts. Anal sac “expression” can also occur when dogs are scared, releasing an unpleasant, fishy odor.

Anal Sac Diseases

Numerous conditions can affect the anal glands. Impactions occur when the glands are not expressed properly and the anal sacs do not drain themselves fully. Untreated, this can lead to abscesses and infections. Tumors may also make natural expression difficult and cause a fishy odor to emanate from the anal glands.

More Symptoms of Anal Sac Disease

In addition to fishy smells, a dog with an anal sac disease may exhibit one or more of the following symptoms:

Though even healthy dogs are susceptible to anal sac disease and the resultant fishy smell, certain dogs are particularly likely to suffer from these conditions. These include obese dogs and pets with environmental allergies, dog food allergies, hyperthyroidism, or certain skin infections.

Manual Anal Expression and Additional Treatments

A veterinarian may be able to alleviate symptoms by manually expressing your dog’s anal glands. Pet owners can even learn to do this themselves. Keep in mind, however, that too much manual expression can cause inflammation and scarring. Vets may recommend high-fiber diets for pets who regularly struggle to express their anal sacs naturally. In cases of severe disease, doctors may need to remove the anal sacs.

Diseases of the anal gland are preventable with an appropriate diet, adequate hydration, and careful monitoring.

The Best Way to Get Rid of Fishy Breath in Dogs

If you notice any abnormalities in your dog, make sure to consult your veterinarian immediately. An abscessed tooth, for example, can be very painful. If you don’t notice any problems, but are still worried about your dog’s bad breath, make an appointment and allow your vet to examine your dog and evaluate for possible underlying problems. Reach out out to a veterinary professional as soon as you notice something is amiss is generally the best and quickest way to get the necessary information and ensure your pet gets care they need.