What Causes Bad Dog Breath & How to Get Rid of It

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Bad dog breath is a common condition that can make some pet parents hesitate when getting close to their dog. The American Veterinary Medical Association named February as National Pet Dental Health month; we’re creating awareness about it by talking about causes of bad dog breath, many of which are connected to dental health.

Some causes are rather harmless, such as your dog just ate some cat poop, while others causes could be a sign of a serious underlying health condition. While smaller dog breeds, older dogs, and breeds with short snouts are more prone to having bad breath, a healthy dog shouldn’t have chronic bad breath. In this article, we will explain the common causes of stinky dog breath, the connection between poor oral health and disease, prevention tips, and available treatment options. Learn how to fix bad dog breath for good.

Common Causes of Chronic Bad Breath

Gum Disease

What causes bad dog breath? Gum disease in dogs

The most common cause of bad breath is a build up of bacteria on your dog’s teeth, called plaque. While a healthy mouth has bacteria in it, plaque promotes the growth of ‘bad’ bacteria that produce unpleasant odors, causing bad breath. If plaque isn’t removed, it can cause irritation and inflammation of the gums (gingivitis), which are the first signs of gum disease (also known as periodontal disease). When left untreated, gum disease can be dangerous to your pet’s health. Despite gum disease being preventable with a regular oral hygiene regimen, the American Veterinary Medical Association estimates that roughly 80% of dogs have gum disease by age three. That’s a lot of bad breath! 

An Imbalanced Oral or Gut Microbiome

A healthy mouth (bacteria in the oral microbiome) improves dog health

Balanced gut microbiomes and oral microbiomes are both very important for your dog’s overall health. Many think the route from the mouth to the gut is a one way street, but oral health and gut health are actually quite connected. A microbiome can become imbalanced when ‘bad’ bacteria are present, overpower beneficial bacteria, or grow in abundance too much.  For example, an imbalanced gut microbiome can cause bad breath because an overgrowth of bacteria in the small intestine can produce a lot of smelly gas. This gas can be absorbed into the bloodstream and eventually exhaled, causing bad breath. This suggests that some conditions related to imbalances in the gut microbiome can cause bad breath. 

Alternatively, an imbalanced oral microbiome can disrupt the balance of bacteria in the gut microbiome. Dogs swallow a lot of saliva, which contains bacteria from the mouth, so it’s no surprise some of those bacteria end up living in the gut. Too many ‘bad’ bacteria in the mouth could end up growing in the gut, causing an imbalanced microbiome, which can also contribute to bad breath. 

Diseases or Health Conditions 

Dog Disease or Health Conditions that are connected to bad breath: Dog diabetes, Dog Liver Disease, & Dog Kidney Disease

There are numerous diseases and health conditions connected to bad breath, that’s why there are tests that use breath to detect the early onset of certain diseases in a non-invasive way. Of the more well known connections between disease and bad breath are diabetes, liver disease, and kidney disease. 

  • Diabetes can cause a buildup of ketones, a byproduct from the body breaking down fat instead of glucose, resulting in breath smelling sweet, fruity or like nail polish remover. Additionally, dog diabetes can also result in high sugar levels; the increased sugar content of saliva is the best food for bad, odor-producing bacteria to thrive. 
  • Liver disease can cause the breath to smell musty or like a dead animal. This is because the liver is no longer able to properly filter out toxins so stinky sulfur compounds, such as thiols, are released into the lungs. 
  • Kidney disease can result in high urea levels in the body, causing the breath to smell like urine or fishy. Kidneys are also an important organ for filtering out toxins.

While less common in dogs, bowel obstructions, acid reflux, indigestion, and other gastrointestinal issues can manifest as bad breath. This is because bad smells associated with digestion don’t move in the right direction in the intestinal tract. More importantly, some bad-breath causing conditions can be exacerbated with poor oral hygiene. For example, bad bacteria that enter the bloodstream through inflamed gums can cause an infection. This can worsen canine diabetes by increasing insulin resistance and making it harder to manage blood sugar levels. 


How to Prevent Bad Dog Breath

How to prevent or fix bad dog breath, brush their teeth regularly

Gum disease is the most common cause of bad breath in dogs, so taking care of your dog’s oral microbiome with these good oral hygiene practices is the first line of defense for preventing bad breath:

  • Regularly brushing your dog’s teeth with dog-specific toothpaste and brush is the most effective way to remove plaque buildup around your dog’s gumline. 
  • Providing your dog with lots of chew toys is also an effective way to improve oral health because the gnawing process knocks off plaque and can increase saliva production to wash away bacteria. 
  • Routinely check your dog’s teeth for signs of gum inflammation or worsening of gum health to know if you need to make changes to your dog’s oral hygiene practices. This article does a great job explaining and showing the different stages of gum disease so you know what to look out for. The good news is that the early stages of gum disease are reversible with positive changes to oral hygiene practices. An annual mouth checkup and/or dental cleaning with your veterinarian can help you stay on top of your dog’s oral health.  


A healthy and balanced diet can help prevent smelly dog breath.

For example, certain ingredients in your dog’s food and/or treats could be negatively impacting your dog’s digestive system, resulting in bad breath due to an imbalanced gut microbiome. Furthermore, nutrients missing from your dog’s diet can also negatively affect your dog’s oral health. For example, it has been shown that deficiencies in vitamin A, vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid), and vitamin B9 (folic acid) are associated with early signs of gum disease. Therefore, it may be necessary to supplement your dog’s diet with a multivitamin or more liver, fish, and bananas (a great treat!). 

Learning about your dog’s oral health and ways to promote a healthy oral microbiome are also important for preventing bad breath. AnimalBiome’s Oral Health System can provide detailed insight into the health of your dog’s oral microbiome by identifying bacterial imbalances and noting the presence of bacteria known to contribute to gum disease.

The system also includes a prebiotic, called TEEF!, to add to your dog’s water. This prebiotic can provide the healthy bacteria in your dog’s mouth with all the nutrition they need to thrive. This can treat and prevent gum disease by reducing the amount of ‘bad’ bacteria in your dog’s mouth that also contribute to bad breath. 

How to fix bad dog breath

If maintaining good oral hygiene practices and a healthy lifestyle doesn’t seem to alleviate your dog’s bad breath, it is time to talk with your veterinarian. He or she can rule out an underlying health issue, help recommend dietary changes, and may suggest professional dental cleaning. 

You might enjoy reading, New Ways to Protect Your Dog from Gum Disease.

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