The Relationship Between Bacteria & Your Dog’s Dental Health

The key to understanding your dog’s dental health lies in the oral microbiome, where a balance between beneficial and harmful bacteria plays a pivotal role. This article delves into how bacteria contribute to the progression of dental disease, from plaque formation to advanced periodontal disease, and how it can lead to tooth loss, infection, and systemic health effects.

Apr 03, 2024·11 min read
The Relationship Between Bacteria & Your Dog’s Dental Health

Dental disease is considered one of the most common health problems in dogs. By age three, a staggering 80% of dogs have some signs of dental disease. While bad breath might be the first thing owners notice, dental disease has far more serious consequences than just an unpleasant odor. A dog’s dental health plays a critical role in their overall well-being. Understanding this begins with recognizing the central role of bacteria in the development and progression of canine dental disease.

Key facts

  • Bacteria are central to canine dental health. Both beneficial and harmful bacteria exist in a balanced oral microbiome in healthy dogs, and imbalances can be associated with dental disease.
  • Dental disease is progressive. It typically begins with plaque which hardens into tartar, leads to gingivitis, and then culminates in advanced periodontal disease with tooth loss, infection, and potential systemic health effects.
  • Bad breath, plaque buildup, inflamed gums, loose teeth, and difficulty eating are all signs that require veterinary attention.
  • Routine professional dental cleanings under anesthesia, along with consistent at-home dental care, are the best ways to prevent significant dental disease in your dog.
  • Treatment for dental disease often includes dental cleanings, extraction of diseased or damaged teeth, antibiotics, and pain management.

The Canine Oral Microbiome

You’ve probably heard of probiotics and the important role of “good” bacteria in our gut. But did you know the same is true for the oral cavity? In humans, the mouth of an average adult harbors 50–100 million bacteria of approximately 700 different species. Similar to humans, the dog mouth also has a complex community of bacteria (along with other microscopic organisms including fungi, viruses, archaea, and protists) known as the oral microbiome

These organisms can be commensal (helpful to the host) or pathogenic (harmful). In a healthy mouth, this microbiome exists in a state of balance. However, changes in bacterial populations can create conditions favoring disease-causing bacteria, which may be associated with dental issues ranging from periodontal disease, tooth root abscesses, and oral tumors. Additionally, existing dental disease can worsen an imbalance in the microbiome. 
Further research is needed to determine the specific types of bacteria isolated from healthy and diseased canine mouths, and there is also individual variation in the microbiome. Common bacteria associated with healthy canine mouths may include species from the genera Bergeyella, Moraxella, Capnocytophaga, and Neisseria. On the other hand, Porphyromonas, Tannerella, and Fusobacterium species are often associated with dental disease.

A close-up of a veterinarian's gloved hands opening the mouth of a black and tan dog to examine its teeth, with a white background.

Common Dental Health Issues in Dogs

There are several types of dental disease that are common in our furry family members.

  • Periodontal Disease: This is the most common dental problem affecting dogs, and is a serious and progressive condition affecting the gums, bone, and ligaments that support the teeth. Advanced periodontal disease leads to pain, tooth loss, tooth root abscesses, and in some cases, can even cause systemic health problems.
  • Tooth Fractures: Dogs, especially those who chew aggressively, can fracture their teeth on hard objects. Fractures can expose the sensitive tooth pulp, causing pain and infection.
  • Malocclusion: This refers to a misalignment of a dog’s teeth when the upper and lower jaws don’t meet properly. Malocclusions can cause crowding of teeth, discomfort, and abnormal wear on the teeth, predisposing these dogs to significant dental issues in the future. 
  • Retained Deciduous Teeth: Puppies have “baby teeth” (deciduous teeth) that are meant to fall out as adult teeth come in. Sometimes deciduous teeth don’t fall out on their own, leading to crowding and other dental issues if they are not extracted.
  • Oral Tumors: Dogs can develop both benign and cancerous oral tumors. Any unusual growth or lump in the mouth should be promptly evaluated by a veterinarian.

Symptoms of dental disease in dogs may depend on the underlying condition and range from subtle to obvious. Early signs include bad breath (halitosis), yellow or brown buildup on the teeth, and red, inflamed gums that might bleed easily. As dental disease progresses, you might notice your dog has loose or missing teeth, struggles to eat or chew, drops food from their mouth, or paws at their face. Excessive drooling, sometimes containing blood, or swelling around the face can also occur. 

Even if you don’t see signs of dental disease, regular veterinary checkups and routine dental cleanings under anesthesia are essential – many signs of dental disease occur below the gum line and may only be visible on dental X-rays.

How Bacteria Cause Dental Health Problems

To explore how bacteria contribute to dental health problems, let’s take a closer look at the progression of periodontal disease in dogs. The main culprit is bacteria, which create a sticky film called plaque on the teeth. Within days, this film hardens into hard tartar (also known as calculus), setting the stage for a cascade of problems:

  • Gingivitis: Gums become red, inflamed, and bleed easily. Luckily, with prompt intervention, gingivitis can be reversed.
  • Early Periodontitis: As inflammation takes hold, the gums begin to recede and pull away from the teeth. Although it might not be obvious at first, bone loss is already starting.
  • Moderate Periodontitis: Bone loss becomes more noticeable, creating pockets between the teeth and gums. These pockets harbor bacteria, causing bad breath and increasing the risk of teeth becoming loose.
  • Advanced Periodontitis: This stage is marked by severe bone loss (often more than 50%). Deep pockets around the teeth make infections, such as tooth root abscesses, common. At this point, the tooth may fall out or need to be removed, and the infection can spread, impacting your dog’s overall health, including their heart and other organs.

Another example of bacterial-related dental disease is a tooth root abscess. A tooth root abscess occurs when bacteria invade the root of a tooth, leading to pus-filled swelling and infection. This type of bacterial infection in dogs happens most commonly when a tooth is fractured, exposing the sensitive inner pulp, or as a result of severe periodontal disease. Abscesses are painful and often cause external swelling on the cheek or under the eye. Other symptoms include reluctance to eat, drooling, and bad breath. Tooth root abscesses require immediate veterinary attention for treatment with antibiotics, pain management, and extraction of the affected tooth.

A small dog with a black and white coat holding a blue and white toothbrush in its mouth, sitting on a wooden floor against a blurred background.

Factors Contributing to Bacterial Overgrowth 

The main factor contributing to dental disease and bacterial overgrowth in our dogs’ mouths is lack of consistent dental care. Most people brush their teeth twice a day and visit the dentist every six months. Without regular brushing and professional cleanings, plaque and tartar rapidly build up, creating an ideal environment for harmful bacteria to flourish.

Other contributing factors include:

  • Diet: Most dog foods (except for prescription dental diets) do not provide natural abrasive action and will not help control plaque accumulation. 
  • Breed Predisposition: Small breed dogs and brachycephalic breeds (those with short, flattened faces like Pugs and Bulldogs) tend to have smaller mouths and overcrowded or misaligned teeth, making them more prone to plaque buildup and dental disease.
  • Systemic Health Issues: Underlying medical conditions like diabetes or immune disorders can make dogs more susceptible to dental issues.
  • Age: As dogs get older, their immune systems become less robust, and dental care may become more difficult, increasing the risk of bacterial overgrowth and tartar buildup.

Diagnosing Bacterial-Related Dental Health Issues

Diagnosing bacterial-related dental diseases in dogs begins with an oral exam and cleaning performed by your veterinarian, while your dog is under anesthesia. This allows them to assess the extent of plaque and tartar buildup, evaluate the health of the gums, and check your dog’s teeth for any signs of damage or disease. Bloodwork will be required before this procedure to make sure that there are no health concerns that may make anesthesia risky. 

Dental X-rays are key for providing a complete picture of your dog’s dental health. These images help your vet evaluate the health of the tooth roots below the gumline, any hidden signs of infection, and the level of bone loss around the teeth. Your vet will also use a probe to check for pockets in the gums surrounding the teeth. 

In the case of an oral tumor, a biopsy (removing part of all of the mass for evaluation) will likely be recommended.

Treatment Options

Treatment for dental disease in dogs depends on the type and severity of the problem. For mild gingivitis, a dental cleaning under anesthesia is the best treatment option. This involves removal of plaque and tartar above and below the gum line, followed by polishing of the teeth. Your veterinarian will also emphasize the importance of following up with at-home dental care. 

As dental disease progresses, more intensive treatments will be needed. This includes the extraction of loose or severely infected teeth. In some cases, referral to a board-certified veterinary dentist for a root canal might be an option instead of tooth extraction.

Treatments for other dental problems:

  • Oral masses: Benign masses may be surgically removed, while malignant tumors often require more complex treatments and referral to a veterinary oncologist. 
  • Tooth root abscess: These painful infections require both antibiotics and extraction of the infected tooth. Antibiotics alone may improve the infection (and symptoms) for a short amount of time, but if the underlying cause is not addressed, it will only recur.

Regardless of the specific treatment, it’s important to consider your dog’s overall health. Underlying conditions may influence the treatment plan and necessitate additional care during dental procedures while your pet is under anesthesia. Pain management is another important consideration, and is achieved with general anesthesia, local nerve blocks, antiinflammatories, and pain medication.

Prevention Strategies

The good news is that, in most cases, canine dental disease is largely preventable. The best way to prevent dental disease in your dog is through routine dental cleanings under anesthesia by a veterinarian. 

In addition, implementing a consistent at-home dental care routine is essential. This may include:

  • Daily tooth brushing
  • Dental chews, treats
  • Dog dental powders
  • Water Additives
  • Prescription dental diet
  • Probiotics

Probiotics are live, “good” bacteria that may potentially help support your dog’s dental health as well as their gut health. The idea is that good bacteria in the mouth can out-compete harmful bacteria, help reduce inflammation, and even freshen breath. While probiotics shouldn’t replace regular brushing and professional cleanings, they might be a useful addition to your dog’s dental care routine. Look for probiotic products specifically formulated for dogs, and always consult your veterinarian before starting your dog on any new supplements.


Dental disease is a common problem in dogs, and it’s closely related to the bacterial population in their mouths. Understanding how bacterial imbalances lead to plaque formation, tooth decay, and gum disease is an important step in prevention. Working with your veterinarian to establish a dental care routine that includes both professional cleanings and at-home care is the most effective way to combat bacteria and safeguard your furry friend’s dental and overall health.


How often should my dog have a professional dental cleaning? 

The frequency depends on several factors, such as your dog’s breed, size, and individual dental health needs. Your veterinarian can provide a recommendation by looking in your dog’s mouth, but many adult dogs need dental cleanings at least once a year.

How do bacteria cause bad breath in dogs? 

Bad bacteria cause decay and break down food particles, producing foul-smelling sulfur compounds that contribute to bad breath. 

Can bacteria from my dog’s mouth make me sick? 

The risk of direct transmission of illness is generally low for healthy individuals. Still, good hygiene practices are always wise. The exception is a dog bite wound, which can become infected and can cause significant disease if not treated appropriately. If you are bitten by a dog, see your doctor immediately, even if the wound appears minor. 

Do probiotics help with dog dental health? 

Probiotics show potential benefits for canine oral health, but research is ongoing. They are also beneficial for gut health and are generally considered very safe. However, they should not replace other types of dental care. 

My dog hates having their teeth brushed. What can I do? 

Start slow and use positive reinforcement to reach your long-term goal of daily brushing. In the mean time, consider using alternatives like dental chews, water additives, dental powders, and special dental diets.


Liza Cahn, DVML

Liza Cahn, DVM

Dr. Liza Cahn is a veterinarian who graduated from Michigan State University’s College of Veterinary Medicine in 2013. She has five years of experience working as a veterinarian in small animal practice in Washington and California. She loved working with dogs and cats and educating owners on all aspects of veterinary medicine, especially animal behavior and dermatology.

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The information contained within this site is not intended as a substitute for professional medical or veterinary advice. PetLab Co. is not intended to diagnose, treat, cure or prevent any disease. If your pet has, or you suspect your pet has any medical condition, you are urged to consult your veterinarian. Medical conditions can only be diagnosed by a licensed veterinarian. These statements have not been evaluated by the Food and Drug Administration. Results May Vary. Not intended for human consumption. Please consult your veterinarian regarding any change in treatment or supplementation.
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