How Is Bad Breath Connected to Your Cat’s Oral and Gut Health?

If your cat has bad breath, the cause is often an overgrowth of harmful bacteria, either in the mouth or in the gut. Too many harmful bacteria can create an imbalance in your cat’s oral or gut microbiome.

So what is a microbiome? It’s a community of bacteria, fungi, and other microbes that live in your cat’s body and are essential for good health. The gut microbiome lives in your cat’s digestive tract, and the oral microbiome has its own community of important bacteria and other microbes that live in your cat’s mouth.

When the gut microbiome contains too many harmful bacteria, the smelly gas those bacteria produce gets absorbed into the bloodstream and is eventually exhaled as stinky cat breath. That’s one reason conditions related to imbalances in the gut microbiome can cause your cat to have bad breath. 

How Does a Cat’s Mouth or Gut Become Imbalanced?

A microbiome is imbalanced when it’s missing “good” bacteria, has too many harmful bacteria, or doesn’t have enough diversity. Factors like disease, age, diet, and medications—especially antibiotics—can cause bacterial imbalances in your cat’s mouth or gut. 

Missing Good Bacteria

Too Many Harmful Bacteria

Not Enough Diversity

How Can You Give Your Cat Relief Right Now?

For cats with severe or chronic bad breath caused by poor gut health, we recommend our KittyBiome™ Gut Restore Supplement.

The supplement introduces an entire community of beneficial cat-specific bacteria to add diversity and bring balance to the gut while relieving symptoms. Gut Restore is a fecal microbiota transplant (FMT) in an oral capsule. FMT has been shown to improve a wide range of symptoms associated with gut microbiome imbalances. Replenishing any missing bacterial populations can often resolve symptoms quickly by restoring a healthy balance to your cat’s gut. If possible, we still recommend testing your cat’s gut microbiome with a Gut Health Test. 


For occasional or mild bad breath and daily gut health support, we recommend our KittyBiome™ S. boulardii + FOS Powder.

This probiotic and prebiotic supplement is designed to support healthy gut function by promoting the growth of beneficial bacteria. It contains the probiotic yeast Saccharomyces boulardii, which helps rebalance the gut and has anti-inflammatory properties. It also contains fructo-oligosaccharides (FOS), a prebiotic that promotes gut health and immune function by feeding “good” gut bacteria.

How Can You Know What’s Going On in Your Cat’s Oral and Gut Microbiome?

We recommend testing your cat’s oral and gut microbiomes. Get 20% off when you purchase our Oral Health Test and Gut Health Test together. Use code BADBREATHBUNDLE at checkout.

You can test your cat’s oral microbiome with our at-home KittyBiome™ Oral Health Test.

This easy test can assess the health of your cat’s mouth, revealing any bacterial imbalances that may lead to bad breath, gum disease, tooth loss, and other health issues. You send us a swab of your cat’s gums, and we analyze all the bacteria in your cat’s mouth. The test can also help you evaluate the effectiveness of any oral health intervention, such as tooth brushing, oral prebiotics, or dental cleanings. 

Test your cat’s gut microbiome with our at-home KittyBiome™ Gut Health Test.

Gut microbiome testing can give you a detailed understanding of what’s going on in your cat’s gut, revealing any imbalances that may cause bad breath. 

You send us a small poop sample from your cat, and we do the rest. Using DNA sequencing, our scientists analyze all the types of bacteria in your cat’s poop and compare them to our healthy cat reference set to determine if an imbalance is present. We then provide an interactive online report on your cat’s gut microbiome with personalized diet and supplement recommendations to help relieve symptoms and improve your cat’s digestive, oral, and overall health. 

Health Tip


Taking care of your cat’s oral microbiome with good oral hygiene practices (like daily tooth brushing with a cat-specific toothpaste) is the first line of defense for preventing bad cat breath.

Feeding a healthy, balanced diet is the best way to manage your cat’s gut microbiome. If you’ve taken our Oral Health Test or Gut Health Test, follow the diet recommendations in your cat’s personalized report to support the growth of beneficial bacteria. Since the gut microbiome is an ever-changing ecosystem that is impacted by multiple factors, including diet and medications, we suggest re-testing your cat’s gut health annually or anytime symptoms arise. A well-balanced gut microbiome will help your cat live a healthier, happier life. 

Learn More About Oral Health for Cats

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