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Bad Breath in Dogs: Causes, Treatments, and Prevention

Studies show that over 80% of dogs will develop dental disease by the age of three. Could this be the cause of your own pup’s bad breath? We discuss the most popular at-home methods for preventing bad breath in dogs and answer one of the internet’s most commonly asked questions: Why does my dog’s breath smell so bad?

Written by Raquel Astacio. Published in November 2022.

Have you ever met a dog who had the most unbearably bad breath? Maybe it was even your own dog. Let’s be honest… there aren’t too many pups out there who smell minty-fresh. For most dogs, their breath smells… well, dog-ish. But when that stench goes beyond just doggy odor and crosses over into full-on foul breath territory, it might signal that something is going on.

There are many reasons a dog may develop a downright stinky stench. Dental disease, chronic systemic issues, and diet can all play a role in the odor of your best friend’s breath. But the leading cause in most cases? Dental disease. This is usually caused by poor oral hygiene or genetic factors.

Surprising as it may seem, dental disease is one of the most common health issues a dog may face. In fact, according to the American Veterinary Dental College, most dogs and cats will have some evidence of periodontal (gum) disease by the age of three. And one of the most notable signs of dental disease in dogs? You guessed it - bad breath.

Of course, dental disease isn’t the only cause of bad breath in dogs. Today, we’re going to dive deeply into the topic of bad breath and answer one of the most frequently asked questions on the internet: why does my dog’s breath smell so bad?

Causes of Bad Breath in Dogs

Bad breath can be caused by several things, from diet to chronic illness. But the most common cause of bad breath by far is dental disease. President of the American Veterinary Medical Association, Dr. Jose Arce, had this to say on the matter:

“Oral disease is one of the most frequently diagnosed health problems for our dogs and cats, and it can have serious consequences for our pets’ health,” said Dr. Arce.

While bad breath is certainly not a desirable trait, it can be an important signalment of this all-too-common canine health problem. Fortunately, dental disease is easily preventable (a matter we’ll discuss a bit later). Before we can understand how best to prevent and treat dental disease, we must first learn what causes it. Let’s take a closer look.

Dental Disease

Dental health is one of the most critical aspects of your pet’s overall well-being. Unfortunately, it is also one of the few things that may go overlooked. After all, how many of our dogs will allow us to easily examine their mouths?

Studies show that dental disease is one of the most common medical conditions seen by veterinarians. In fact, according to the Veterinary Centers of America, over 80% of dogs over the age of three have active dental disease. Dental problems can be hard to catch because the symptoms are often so subtle. However, they commonly include bad breath, reluctance to eat hard or crunchy food, excessive drooling, or pawing at the face.

Dental disease is usually caused by a build-up of plaque and tartar. When these two dangerous substances form, they can cause significant damage to your dog’s teeth and gums. The speed at which plaque and tartar will form differs from dog to dog, though most of it has to do with your pup’s genetics. Let’s take a closer look at the sinister role plaque and tartar play in canine dental disease.


Whoever said that a dog’s mouth is cleaner than a person’s might not have been entirely correct. A more accurate statement may be that a dog’s mouth is just as dirty, and bacteria ridden as a person’s!

Your dog’s mouth is home to thousands of bacteria - a regulated amount of which is considered healthy and normal. However, the problems begin when bacteria start to populate at an out-of-control rate on the tooth’s surface, triggering the formation of an invisible, sticky film called plaque.


Plaque will begin to thicken and mineralize if allowed to remain on the tooth’s surface for a prolonged period, gradually evolving into tartar. Tartar can be thought of as an upgraded version of plaque - it is thicker, stronger, and more challenging to remove. As plaque and tartar develop, an associated biofilm is created, which the VCA describes like this:

“In very simple terms, a biofilm is a collection of bacteria structured in such a way as to be very resistant to removal and difficult for antibiotics to access,” says the VCA. “Plaque bacteria which comes into contact with the gingiva (the gums) can result in inflammation (gingivitis). Gingivitis is always the first stage of periodontal disease, and it is the only truly reversible stage.”

The speed at which plaque and tartar develop will vary. However, they can be easily prevented using slight adjustments to your pup’s diet and routine - we’ll touch more on this subject later. However, while inarguably the most common, dental disease is not the only cause of bad breath in dogs. Another primary cause of breath-related stench is organ disease or failure.

Organ Disease or Failure

As we’ve discovered, a dog’s foul breath may indicate something is wrong within the body. Now that we’ve discussed the ins and outs of dental disease, let's turn our attention inward and discuss the link between bad breath and organ failure - specifically when it comes to the kidneys and liver.

Bad Breath and Kidney Disease

Bad breath is often one of the first indicators of kidney failure - a common health problem, especially for senior pets. When a dog’s kidneys perform inadequately, the breath may smell of ammonia or urine. While not pleasant to envision, the logic behind this is simple…

If a dog’s kidneys are not functioning properly, urea (an organic component of urine) is not being eliminated effectively. When urea remains within the body longer than it should, it can cause an ammonia smell which, in turn, makes the dog’s breath smell of urine.

Kidney disease can be linked to bad breath in more ways than one - not only do damaged kidneys cause bad breath, but bad breath (caused by dental disease) can cause damaged kidneys! To simplify the explanation of this process, River Landing Animal Clinic says this:

“When neglected, dental disorders in dogs can become advanced and cause an overflow of germs and bacteria into the mouth,” says RLAC. “These get ingested and enter the bloodstream, causing long-term damages to kidneys and liver.”

Bad Breath and Liver Disease

Bad breath can also be an indicator of liver disease in dogs, especially if it develops suddenly in conjunction with vomiting and diarrhea. Liver disease is another common health problem, especially in older pets.

Bad breath, in this case, is caused by the liver’s inability to break down toxins within the body. Most people report that the smell of their pup’s breath in this situation smells like a dead animal - very foul and rotten - or like fish. In addition to bad breath, a dog with liver disease may lose his appetite suddenly. He may also develop a yellow (jaundiced) tinge to his skin or fluid in the abdomen.


What goes into our body has a significant impact on what comes out of it… and this includes our breath! The diet you feed your pup can impact the smell of his breath (for better or worse). This means that a healthy, well-balanced diet is crucial not just for your dog’s overall health but for their oral health as well. Let’s look at the science behind it all.

Amylase is an enzyme that helps break down carbohydrates as they’re swallowed, enabling our bodies to process the eaten carbs with greater ease and prevent damage to our teeth. A human’s body produces amylase in plenty on its own - a dog’s? Not so much. Dog’s saliva does not contain amylase.

Unfortunately, the absence of this crucial enzyme, paired with your pup’s inability to brush and floss daily, can be detrimental. With dogs, the carbs consumed from their food will stick around in their teeth for extended periods, resulting in increased bacteria. And as we’ve already learned, too many bacteria equal plaque and tartar, which equals dental disease.

To resolve this issue, consider switching your pup to a lower-carb diet vetted by the Veterinary Oral Health Council. Processed foods approved by the VOHC are known to be much more dental-friendly than your run-of-the-mill grocery store brand food and may help prevent serious issues down the line.

Other Causes of Dog Bad Breath

You’ve been able to rule out dental disease, organ failure, and diet as potential causes of your dog’s bad breath. Yet, you’re still knocked off your feet whenever your pup opens his mouth. If this is your situation, it may be time to look at one of these less-common causes of bad breath:

  • Diabetes
  • Heart Disease
  • Oral Tumors
  • Imbalanced Gut Microbiomes

Treating Bad Breath in Dogs

To discover how best to treat stinky dog breath, we must first determine the cause. As we’ve learned, primary causes for bad breath in dogs are dental disease, organ disease or failure, and diet.

Determining the Cause

If your pup is already eating a quality, veterinary-approved diet, we can probably rule that out. The next step? Taking your dog for a vet visit. During this visit, your family vet will perform a thorough dental exam. Most veterinarians can spot dental disease a mile away so long as their patients are cooperative. If your pup’s mouth is loaded with plaque and tartar, it may be time for a dental cleaning. If not, your veterinarian will likely recommend bloodwork to rule out kidney or liver issues.

Routine Dental Cleanings

If your veterinarian suspects that your dog may be dealing with a case of dental disease, they will likely recommend a dental cleaning. During this procedure, your pup will be placed under general anesthesia. The veterinary staff will take radiographs of his entire mouth to ensure that there aren’t any damaged teeth or bone structures. Once this is finished, they will begin to clean and polish your pup’s teeth.

Your veterinary technician will remove all the plaque and tartar using a professional-grade scaler. Once the teeth are pearly-white again, they will then polish the teeth with a protective solution to prevent future plaque build-ups (for a little while, at least). Having your dog’s teeth cleaned regularly is one of the best ways to treat and prevent chronic dental disease.

Dietary Changes

As we’ve learned, carbohydrates can significantly impact your pup’s dental health (and not in a good way). If you suspect that diet may be the cause of your dog’s bad breath, it might be time for a change. Choosing a food low in carbohydrates can be extremely helpful, especially if your pup is prone to poor dental health (bonus points if it’s veterinary-approved).

Treating Kidney or Liver Disease

If your pup’s bloodwork does, in fact, reveal that he has kidney or liver disease, it’s time to have a very frank discussion with your veterinarian about treatment options and prognosis. Pets with early-stage kidney or liver disease may require a change in diet or a new medication. However, late, or end-stage kidney or liver disease pets may require more intensive treatment (fluid therapy, pain medications, etc.)

Preventing Bad Breath in Dogs

Making a few small changes to your pup’s diet or lifestyle can be highly beneficial in preventing dental disease down the line. And most basic steps for prevention start at home. From dental chews to diet changes, there are many home remedies you can use to help your pup combat dental disease.

Teeth Brushing

Routinely brushing your dog’s teeth can help reduce plaque and promote better oral hygiene. It’s important to use toothpaste specifically designed for dogs, as human toothpaste can contain harmful ingredients like xylitol which is toxic to dogs. With a bit of training, most dogs will learn to enjoy having their teeth brushed!

Chew Toys and Dental Treats

You can help your dog take care of their teeth naturally by providing chew toys and dog treats for bad breath. Chewing prevents plaque and tartar build-up and also relieves boredom - keeping your dog healthy and happy. Make sure to pick dog chew toys and treats appropriate for your dog’s size and age, specifically designed to clean teeth, and freshen breath, such as a dental bone, nylabone, or dental stick.

Promoting a Dental-Friendly Lifestyle

A balanced, veterinary-approved diet, regular exercise, and routine check-ups are all essential in preventing systemic disorders and accompanying dental disease. Like people, dogs need a healthy, well-balanced diet and plenty of exercise to stay healthy. By keeping your dog healthy, you can help your veterinarian catch any problems early on, saving your dog from experiencing more serious health issues.

There is an overwhelming number of products on the market today for pet dental health, from oral hygiene wipes to water additives. To narrow down the best product(s) for your pup, do your research or ask your veterinarian for guidance.

FAQs About Canine Bad Breath

"Should I be worried if my dog has bad breath?"

The degree of concern you should have while dealing with your dog’s bad breath has everything to do with the cause. Dental disease, for example, is treatable and not usually cause for concern. On the other hand, organ disease or failure is more serious and should be addressed promptly. If you can rule out diet, it may be time to get your veterinarian involved to discover the true cause of your pup’s odor.

"Is bad breath in dogs a possible sign of cancer?"

While bad breath in dogs can be caused by a few factors - such as dental disease, dietary issues, or even just eating something stinky - it can also be a sign of serious illness, including cancer. In fact, one of the first symptoms of oral cancer in dogs is often bad breath. While bad breath alone is not enough to diagnose cancer, it can be an early indicator of the disease.

If your dog’s breath suddenly smells extremely bad, it’s important to take them to the vet for a check-up. Other signs of oral cancer can include drooling, pawing at the mouth, difficulty eating, inappetence, lethargy, and weight loss. However, it’s important to remember that bad breath can have many causes, so don’t panic if your dog has stinky breath - just make sure to have them checked out by a trusted veterinarian.

"What if my dog has both bad breath and excessive licking?"

If your dog is suffering from bad breath and is also licking his lips excessively, he likely has a dental problem. Just like humans, dogs need regular dental care to prevent the build-up of plaque and tartar. Without proper care, plaque can harden into tartar, leading to gum disease, tooth loss, and other health problems. If your dog’s breath is less than pleasant, be sure to schedule a visit with your veterinarian. In addition to regular brushing, your dog may also benefit from routine professional teeth cleaning. And by taking care of your dog’s teeth early on, you can help prevent serious problems down the road.

"Why does my dog's breath smell like fish?"

If your pup’s bad breath has a hint of fishiness to it, it may be time for a visit to your veterinarian. Owners of dogs with chronic liver disease often report that their pup’s breath smells of fish or even death - a foul or rotten smell, in most cases. When the liver begins to fail, it cannot process toxins within the body, which is the cause of this foul gaseous odor.

If your pet’s breath suddenly turns stinky, especially if accompanied by other symptoms such as vomiting, diarrhea, yellow (jaundiced) skin or eyes, or drastic weight loss, he may be suffering from liver disease or failure. It is essential to address this problem early on to get your pup on an effective treatment plan.


So, there you have it - everything you’ve ever wanted to know about bad breath in dogs! While stinky breath is an unpleasant condition for both dogs and their owners, it’s thankfully one that is preventable and can be easily treated. Following the home remedies, tips, and tricks covered here can help keep your furry friend’s breath smelling sweet (or at least not quite as bad).

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