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How the Bacteria in Your Dog’s Mouth Affect Their Oral Health


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There are hundreds of bacteria in a dog’s mouth. The mouth offers an ideal environment for bacteria, providing a stable temperature, moisture, and nutrients. It is home to many microbial communities, which coat a dog’s teeth, tongue, gums, and palate (the roof of the mouth).

These bacteria can have either a helpful or harmful effect on your dog’s dental health, as well as their overall health.

What are the types of bacteria in a dog’s mouth?

Collectively, the bacteria in a dog’s mouth are called the oral microbiome. The oral microbiome plays critical roles in digestion, energy production, immune function, and disease prevention (Deo, 2019).

Like other systems in the body, the oral microbiome relies on a balance of beneficial (“good”) and pathogenic (“bad”) bacteria. Good bacteria keep bad bacteria in check by forming a biofilm—a layer of bacteria that stick to each other and act as a protective barrier. When this barrier is broken, the bad bacteria can invade and cause gingivitis, tooth decay, and bad breath.

How do the bacteria in a dog’s mouth affect their health?

The effects of the bacteria in a dog’s mouth aren’t limited to their oral health. The oral microbiome can also affect a dog’s overall health. 

Periodontal disease (gum inflammation and infection) not only causes tooth decay, but can also affect other systems throughout the body. This type of disease is especially common in dogs. Some studies estimate that more than 80% of dogs have some form of periodontal disease (Stella, 2018). 

Once the bad bacteria are in a dog’s mouth, they can spread through the bloodstream and reach the heart, kidneys, liver, and brain. This can cause infections and clotting abnormalities (Niemiec, 2008). Good dental care, as guided by a veterinarian, may help lower the morbidity and mortality rates of dogs with periodontal disease (Pereira dos Santos, 2019).

How to test your dog’s oral health

Before the development of genomic sequencing techniques, it was difficult for scientists to study the oral microbiome (Deo, 2019). In contrast, today’s DNA sequencing technology allows us to identify the bacteria in a dog’s mouth at a high level of resolution. 

Scientists are currently making advances in understanding the role that good and bad bacteria play in the development of periodontal disease. For example, in one study, researchers found that periodontal disease resulted in a significant increase in Bacterioidetes, Fusobacterium, and Porphyromonas species, while simultaneously causing a decrease in Actinobacteria and Proteobacteria (Santibanez, 2021). 

Oral Health Test
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At Embark, in partnership with AnimalBiome, we’re now offering this type of  technology to assess canine oral health through the Oral Health Test. This at-home test identifies the bacteria in your dog’s mouth and compares them to a reference panel of healthy dogs. This information can help assess their oral health and provide guidance about when an intervention is needed.

Signs of poor oral health in dogs

If your dog shows any of these signs of possible oral disease, make an appointment with your veterinarian:

  • Bad breath (halitosis)
  • Teeth that are discolored or covered in tartar
  • Loose teeth
  • Drooling or dropping food out of the mouth
  • Bleeding from the mouth (or blood in their water bowl)
  • Frequent pawing at the mouth
  • Swelling on the side of the nose or under the eye
  • Shying away from being touched in the mouth area
  • Loss of appetite or difficulty chewing

How to improve dog oral health

Every dog benefits from regular dental care. It is especially important for small-breed dogs, because they are more often diagnosed with periodontal disease. 

If your dog has periodontal disease, talk to your veterinarian about a dental cleaning. The single most effective thing you can do at home to control plaque and improve your dog’s dental health is to brush their teeth daily (Allan, 2018).

Remember that oral health is part of a comprehensive care plan for your dog that includes regular teeth brushing at home, as well as oral examination and cleaning by a veterinarian. You can also use dental chews and prescription diets as part of an oral care plan. Learn more about oral hygiene for every stage of a dog’s life.

Kari Cueva, DVM

Dr. Kari Cueva, DVM, is the Associate Director of Veterinary Genetics at Embark. She is a 2011 graduate of the University of California, Davis College of Veterinary Medicine. Her research background includes four years in canine genetics with Dr. Mark Neff, and genetics fellowships at Cornell University and the National Institutes of Health. She continues to practice emergency medicine at a local animal hospital.

Read more about Kari Cueva, DVM

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