What Causes Bad Breath In Dogs & How To Get Rid Of It

Gum disease, also called periodontal disease, affects about 80% of dogs by the time they are three years old. It’s caused by a buildup of bacteria on your dog’s teeth, called plaque, and is the most common cause of bad breath in dogs.

A healthy dog mouth has bacteria in it, but plaque promotes the growth of ‘bad’ bacteria that produce the unpleasant odors behind bad breath. If plaque isn’t removed, it can cause irritation and inflammation of the gums (gingivitis), which is the first sign of gum disease.

When left untreated, gum disease in dogs can lead to painful infections and dental problems that can also cause bad breath. And it doesn’t stop there - gum disease is linked to health issues that are dangerous to your dog’s overall health.

There are numerous diseases and health conditions connected to bad breath; that’s why for humans, 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. Here’s how:

• 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 fish. Kidneys are also an important organ for filtering out toxins.

The microbiome is a term that is used to describe a dynamic and complex community of bacteria, viruses, fungi, and other microorganisms. In your dog, for example, they have a gut microbiome in their intestinal tract and an oral microbiome in their mouth. Both play key roles in your dog’s overall health. When there aren’t enough beneficial bacteria or too many harmful bacteria, a microbiome is considered imbalanced.

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. Bacterial communities in both the gut and the mouth are connected to bad breath as well.

An Imbalanced Gut Microbiome Can Cause Bad Breath

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.

An Imbalanced Oral Microbiome Can Cause Bad Breath

Too many harmful bacteria, like E. coli and other pathogens that grow in anaerobic pockets, can give off an unpleasant odor. In more extreme cases, an infection of a tooth or gum tissue could also create foul smelling breath.

Oral microbiome imbalances have consequences on the gut microbiome too. 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. An imbalanced gut microbiome is associated with numerous health conditions, from digestive issues to immune system disorders.

Smaller dog breeds, older dogs, and breeds with short snouts are more prone to having bad breath. If your dog fits these groups, talk with your veterinarian about what oral care practices and lifestyle modifications they recommend to protect your dog from conditions associated with bad breath.

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. Oral tumors, abscesses, and other oral health issues can cause bad breath.  

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.

Periodontal disease is the most common cause of bad breath in dogs, so taking care of your dog’s dental health and oral health are your first lines of defense for preventing bad breath. Here’s what veterinarians say are the most effective ways you can do this:

• Regularly brushing your dog’s teeth with dog toothpaste and toothbrush is the most effective way dog owners can prevent bad breath. Daily teeth cleanings protect against dental disease by removing plaque buildup around your dog’s gum line.  
• 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. Talk with your veterinarian about the best dental chews and dental treats for your pooch.
• 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. Check out this peer-reviewed study about periodontal disease in dogs. It does a great job explaining and showing the different stages of gum disease so you know what to look out for.
• Take your dog in for an annual exam, which will include a checkup of the mouth. Schedule a dental cleaning if your veterinarian recommends it. Most gum disease actually occurs under the gums, so it’s important to have that area examined and cleaned by a professional.