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Dog Bad Breath – Why It Happens & How to Treat It

Author: Dr. Beth Turner

Published: September 20, 2022

Updated: May 21, 2024

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mixed breed dog kissing his owners face

The term "dog breath" generally has a negative stigma associated with it. And more often than not, it is for good reason.

That is unless you are referring to "puppy breath." I will argue with anyone that that is a great smell. But I digress.

Most often, dogs have bad breath from oral health issues. But that isn’t the only reason your dog’s breath may be smelling bad. It can also indicate other medical issues.

What Is Causing Your Dog's Bad Breath?

You should never ignore your dog’s bad breath, especially if your dog has bad breath all of a sudden. While some issues are minor and can quickly be treated, others may require life-long treatment and management. That is why having your dog promptly evaluated by a veterinarian is important.

Some Common Causes of Bad Breath in Dogs

Doggie bad breath happens! Knowing how to prevent or manage it is essential.

However, identifying the underlying cause is one of the first steps in dealing with bad breath. While some causes may be more obvious, like dental disease, others require a thorough workup by a veterinarian. This includes a physical exam as well as other tests (blood work, fecal analysis, x-rays, etc.). Treatment and management of the underlying cause may require medication, supplements, surgery, etc. See more below on how to treat bad breath.

Oral Health Issues

Bad breath is most commonly caused by oral health issues. This can be due to dental (damaged teeth or plaque and tartar buildup), gum (gingivitis – inflammation of the gums), or periodontal disease (advanced disease affecting the teeth, gums, tooth roots, and bone). Over time, as bacteria continues to increase in your dog's mouth, inflammation, and disease spread, leading to bad breath.

short haired dachshund posing for a photo-canva

A veterinarian can tell from a routine health exam how advanced dental disease is, and what the next steps are for treating the problem, based on the severity of the dental disease.

Personal Story: I was doggie-sitting for a friend’s dog. She was a dachshund, and I just loved her. She was used to sleeping in bed with my friend. So, I decided to do the same come bedtime.

As I lay there falling asleep, I noticed this smell. She had moved closer to me and was breathing in my face. Her breath smelt so bad.

Being a veterinarian, I looked into her mouth, and she had significant tartar buildup and gingivitis.

Sadly, her sleeping in the bed ended because the smell was making me nauseous.

Dietary Indiscretion

Dogs are not generally known for their sophisticated palate. There is a myriad of "snacks" that our pooches love to sample that can cause their breath to be less than pleasant. While it is obvious that dogs who love to eat poop (aka coprophagia), either the doggie or kitty kind, will suffer from bad breath. But other snacking options, such as consuming garbage, compost, decomposing animal remains, etc., can all lead to smelly breath. Not only does this cause smelly breath, but it is unhygienic and can put them at risk for other issues such as intestinal parasites, bacterial or viral infections, etc.

If your dog ate something they shouldn't have, as long as you know it isn’t toxic or could cause an intestinal blockage (if it was, contact a veterinarian IMMEDIATELY), monitor them closely for the next 72 hours for any changes in appetite, lethargy, signs of discomfort, or gastrointestinal issues such as vomiting or diarrhea. If you notice any changes, contact your veterinarian.

rotting potatoes bad for dogs to eat-canvaPersonal Story: I can tell you, for a FACT, that the consumption of rotten raw potatoes will cause a dog’s breath to suddenly smell horrific, and the smell lingers for a long time.

My first heart dog was a Rottweiler. To say the least, she LOVED food.

I was letting her run around while we were visiting family. She then was unusually quiet. Her being quiet would bring up the same sense of panic as when a toddler is quiet. She had found a pile of old rotten potatoes, and she gobbled them down.

Had I not known, sadly after the fact, that they had dumped the potatoes at the tree line, I would have panicked over her sudden bad breath.

Besides being fortunate to know why she had sudden bad breath, I was also very lucky she didn’t suffer from any of the toxic effects of raw potatoes.

Raw potatoes contain a compound called solanine, which is toxic to dogs. It can cause gastrointestinal upset (vomiting and diarrhea) and even death if too much is consumed.

Dietary Deficiencies

When dogs lack certain vitamins or minerals, their immune system becomes compromised, increasing the likelihood of them developing other medical issues. Additionally, the bacteria flora of the mouth and the gut will be out of balance when they are lacking proper nutrients. This combination can lead to bad breath.

Your veterinarian will determine what is lacking in your dog's diet and recommend a diet change and/or supplements.


Just like our breath can smell bad from eating certain foods, like garlic or onions, there are some diets, such as fish-based prescription diets, raw diets, homemade diets, etc., that can result in bad breath for dogs.

Additionally, when the kibble size isn’t appropriate for the size of your dog, and it fails to help remove plaque and tartar, bad breath can be the result. That's why there are breed-size recommendations for dry food. Kibble should be large enough to require chewing but small enough so they don't choke on it if swallowed whole.

Toxin Ingestion

When dogs ingest a poisonous substance, whether a solid or liquid, chemical or plant, it can cause sudden bad breath. If you notice a sudden change in your dog’s breath, especially if it smells chemically or like a product you were just using, contact your veterinarian or a poison hotline immediately. Do not attempt to cause your dog to vomit... because...

Gastrointestinal Issues

We tend to forget that the mouth is the beginning of the gastrointestinal (GI) tract. When issues occur further down the GI tract, such as intestinal blockages, cancer, digestive problems, etc., they can result in bad breath since the normal path for the gas and digestive material to leave is blocked.

Additionally, any GI issue that causes vomiting can result in bad breath. Another fairly common cause of bad breath is gastroesophageal reflux disease (GERD). With this disease, the stomach acids come back up into the esophagus, resulting in a foul scent from your dog’s mouth.

senior toy poodle DaisyTeam Story: One of our Seattle-based colleagues adopted a senior toy poodle many years ago. It was apparent that she hadn't had any dental cleanings for years, if not her whole life. So, she was booked in for a dental cleaning. After pulling a few teeth and cleaning things up, the health of her mouth improved.

However, her family kept wondering why her breath still smelled like rotting garbage. Sure enough, poor little Daisy was diagnosed with acid reflux. The sphincter between her stomach and the esophagus wouldn't close properly, so the smell would waft back up. This was even more noticeable when she laid down in bed with her people.

The smell never disappeared completely, but it was greatly improved with medication to strengthen her lower gastroesophageal sphincter. This helped acid from coming back up and irritating her esophagus and throat, so Daisy felt much better with treatment.

Oral Foreign Body

We already mentioned that dogs (well, most) would eat almost anything. This can include sticks, rocks, bones, etc. There are instances where these objects can get wedged between their teeth, cause tooth fractures, or get jabbed into their gum or cheek. See more dangerous chews in our article, as some of these popular chews can be very damaging to teeth and gums.

More often than not, most owners are not even aware that their dog ate anything. Dogs are so good at hiding the pain and discomfort that the foul smell of the infection in their mouth is often first noticed.

yellow labrador dog happy after playing in the leaves-canvaPersonal Story: One of my patients was this perfect Lab. He honestly never did ANYTHING wrong in any way, and he had the best personality.

His owners brought him in because they noticed he suddenly started to have bad breath. They noticed nothing else wrong with him. He was eating, drinking, and acting like his normal goofy self.

When I examined his mouth, I found a stick lodged between his upper premolars. It had traumatized the gum and bone around those teeth and inflamed the roof of his mouth.

Sadly, we had to pull out a few teeth, but his breath improved.

When it comes to sticks, Mother Nature does not make good dog toys!

Oral Tumors

It is fairly common for dogs to get oral tumors. Approximately 6% of all tumors in dogs are oral tumors (both benign and malignant). Oral tumors tend to bleed and often become infected. This combination leads to bad breath.

Respiratory Issues

Bad breath can result when disease, cancer, or infection occurs anywhere within the respiratory system (nose, sinuses, trachea, and lungs). They may have discharge from their nose, but you may not always notice since most dogs lick it off. No wonder their breath stinks.

Anal Sac Issues

Anal glands are literally a pain in the butt! When they become overfilled, infected, or rupture, dogs will lick the area a lot.

The combination of anal sac "juice," infection, and possibly poop creates a smell in their mouth that one will never forget. If you notice your dog dragging their rump on the ground, scooting, or biting at their tail base, you likely need to make an appointment with your vet to have their anal sacs expressed. Read more to get help on controlling anal gland issues.


A very serious complication of this metabolic condition is diabetic ketoacidosis (DKA). This condition can cause a dog’s breath to have an acetone-like odor. Have you ever heard of keto breath? Some feel it is more of a sweet fruity smell. Regardless of how people view the smell, evaluation by a veterinarian is critical, as diabetic ketoacidosis is a critical condition that needs attention right away.

Kidney Disease

Dogs suffering from kidney disease can have very foul-smelling breath, similar to the smell of urine or ammonia. When the kidneys are not functioning properly, toxins and waste material accumulate in the body contributing to bad breath. Your dog needs to be seen by their vet if you are noticing this issue.

Liver Disease

If your dog has really bad breath, vomiting, diarrhea, and jaundice (yellowing of the skin or whites of their eyes), this can indicate they may have liver disease. The liver, like the kidneys, helps remove toxins from the body. When the toxins are not removed due to the fact that the liver isn’t functioning properly, they accumulate in the body resulting in bad breath.

Additionally, a properly functioning liver is important in digestion. Poor digestion can lead to bad breath. That results in a double whammy for smelly breath!

Medications & Supplements

There are many medications, such as antibiotics or corticosteroids, and supplements, such as fish oil, that will cause bad breath. Despite smelly breath, medications and supplements are essential in the treatment of medical issues and should never be stopped without consulting with your veterinarian.

If you suspect fish oil is the culprit for your dog's bad breath, you may choose to supplement with fish oil pills instead of pouring fish oil directly on your dog's food. This is a great fish oil supplement in pill form.

black and white dog opening his mouth to the camera

Ways to Freshen Bad Dog Breath

First and foremost, routine veterinary care not only helps with treating and managing some causes of bad breath, but it is also a critical part of prevention. Identifying health issues early helps prevent or slow the progression of certain diseases, especially those aspects that may lead to bad breath. For example, when diabetes is identified prior to the development of ketones with routine blood work, you can prevent not only bad breath but also life-threatening diabetes keto-acidosis.

When diet (such as fish-based food) is the only culprit for smelly breath, but you want to freshen your dog’s breath, try one of the dental chews we recommend below. The added bonus is that they can also help prevent dental disease, which is the leading cause of bad breath!

Veterinary Dental Care

As mentioned earlier, dental issues are one of the most common causes of dog bad breath. It's important to have your veterinarian perform routine oral exams (which detect dental disease as well as oral tumors) and to have your dog's teeth professionally cleaned by a veterinarian.

Cleaning Your Dog's Teeth At Home

You can take daily steps to prevent dental disease. Besides helping prevent dental disease, these steps also help prevent odor caused by medications or supplements. This can be accomplished by combining one or more of these actions daily:

Do regular inspections of your dog’s oral cavity: Look all over, but especially the back and roof of their mouth.

Brush your dog's teeth: Ideally every day, but at least three times a week.
Use dental chews that are proven to work
  • With any dental product, look for the Veterinary Oral Health Council (VOHC) seal, which ensures that product is certified to retard plaque and tartar on dogs' teeth. You can review the VOHC list.
  • Our team loves these two dental chew options: Whimzees Natural Dental Chews and Purina Dental Chewz

Use water additives for dogs: This one from Orotene doesn't have any flavor. You just add it to your dog's drinking water.

Use an oral rinse for dogs: Oral rinses are different than water additives. These you actually squirt into your dog's mouth. You use a syringe, put it under the cheek, and squeeze it in. Rinses are especially helpful for dogs recovering from dental procedures with extractions, for those who won't allow their teeth to be brushed, won't drink water with additives, or don't like chews. One of my favorites is the Vetoquinol Dentahex Dog & Cat Dental Rinse (for some reason it is not available on Amazon anymore, as of 4/17/23). Vet One ChloraZinc Rinse is also a great option.

Use a canine dental diet: These three prescription diets are scientifically proven to work, Royal Canin, Purina, or Hill’s. These diets are only for dogs with no food allergies or intolerances. And they need to be prescribed by your veterinarian.
  • You can feed a dental diet as your dog's main diet, mixed into other food, or give it as a treat.
  • Be sure to purchase the correct size of kibble for the size of your dog. If the kibble isn't the appropriate size, it won't provide the complete benefit, as some of the benefit is in crunching the kibble.

beagle dog drinking from a raised water bowl

Food, Supplements, and Hydration

Feeding a high-quality and well-balanced diet: This can be beneficial in the prevention, management, and treatment of many of the causes of bad breath on the list. Not only is it essential to prevent nutritional deficiencies, but it can also be used to treat and manage metabolic disorders, such as diabetes and liver or kidney disease, that cause bad breath. For those diets, especially fishy ones, routine teeth brushing and oral rinses can combat those smells!

Being sure that your dog is properly hydrated: This is important in preventing bad breath. Not only does it help flush their mouth, especially if they have licked or eaten something gross, but it also helps flush toxins out of their body. Flushing toxins is especially important for dogs suffering from liver or kidney issues.
  • Try a pet water fountain. Like cats, dogs tend to drink more from a fountain. The water is filtered so it doesn’t get a "stale" taste, and it generally stays cooler.
  • Adding flavoring to their water can often encourage dogs to drink more. Try some water from a can of tuna. You might get fish breath, but it's better than your dog getting kidney disease!
  • How much should your dog drink? For every 1 pound of body weight, your dog should consume ½ to 1 ounce of water per day. You can use this calculator to find out how much for your dog, based on their activity level.

Supplement with prebiotics and probiotics: This can help keep the mouth, gastrointestinal tract, and skin microbiome in proper balance. When they are in proper balance, your dog’s immune system is enhanced, and they are better able to fight off other infections or illnesses that can lead to bad breath. Check out this list of probiotics for our favorite brands.

Supplement with fiber: While fiber may not directly prevent bad breath, its benefits can. Adequate fiber is essential for proper digestion; it helps with constipation and diarrhea, acts as a fuel source for probiotics (boosting the immune system), bulks up the stool to help express anal sacs, and more. This helps prevent or manage several causes of bad breath. Some simple forms of fiber include:
  • Low-sodium green beans like these canned beans, or if organic produce is important to you, these organic beans also don't have any salt or sugar added. 
  • Canned pumpkin (not pumpkin pie) 
  • Apples (no seeds or core and peeled)

Store Toxins Safely

Aside from the fact that toxins can cause bad breath, they can be fatal for dogs. Therefore, always be sure to store any potential toxins, chemicals, or cleaners in sealed containers out of your pet's reach in locked cabinets. It is important to remember that even "natural products," such as bone meal, fish meal, blood meal, etc. (see more in our yard and garden article), can cause not only bad breath but are dangerous in other ways. Therefore, be sure to keep them out of reach from your dog.


husky shephard mix puppy breathing in young girls face

While it may not be everyone’s cup of tea, I LOVE the smell of puppy breath. The sweet smell is likely due to their milk-only diet (nothing fishy in there!) and the fact that their mouth doesn’t contain any of the nasty plaque and tartar that occurs with age. If you are not a puppy breath fan, the smell just gets worse, so it is best to work on keeping it fresh with a good oral hygiene routine.

Your battle with your dog’s bad breath may require combining a few different options, but it will be worth it when you can enjoy kisses and cuddling without the smell!


About the author

Profile picture for Dr. Beth Turner

Dr. Beth Turner

Beth Turner is a veterinarian with over 20 years of experience. She graduated from North Carolina State College of Veterinary Medicine and following graduation, she began her career as an associate veterinarian and worked closely with the local shelter.

In 2007 she accomplished her dream of practice ownership, designing and building her own clinic. Another meaningful role, while running her clinic, was serving as her county's shelter veterinarian. This gave her the opportunity to help improve the lives of many animals in her community as well as work with the rescue she loved. She sold her practice in 2019 to move across the country.