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Does your dog’s stinky breath offend?

Are you wondering how in the world a dog’s mouth is cleaner than a human’s mouth? Or maybe you’re skeptical about this rumor and don’t believe it has any merit at all.

It’s true. Human mouths harbor many germs too, although, as a natural host to bacteria, how clean can our mouths be?

Perhaps a dog’s mouth is not so fresh and clean after all.

In this guide, we’ll compare the mouths of dogs and humans. We’ll talk about what it means to have a clean mouth and when your dog’s morning breath may indicate a more serious health problem.

So, are dogs’ mouths cleaner than humans? Let’s find out!

Do Dogs Have Clean Mouths?

Do dogs have clean mouthsIn general, dogs do not have clean mouths. But neither do humans.

A dog’s mouth and a human’s mouth are viable homes for millions of different types of bacteria. Most types of bacteria are helpful, or otherwise, neutral.

Helpful bacteria clean a dog’s mouth by:

  • Stimulating saliva production
  • Washing away particles of food
  • Disarming bad bacteria

A healthy mouth depends on good oral hygiene habits. So, brushing, flossing, and regular dental visits are super important. In other words, a clean mouth is a healthy mouth.

So, do dogs have clean mouths? Unfortunately, dogs have several strikes against easily maintaining a clean mouth including:

Exposure to bacteria 

Dogs don’t have hands. Canines must pick up everything with their mouth including new bacteria.

Inconsistent dental care

Only about 2% of dog owners regularly clean their dogs teeth. Additionally, vets recommend dogs get deep cleanings once to two times a year. Dental care isn’t consistent, so the odds of developing dental problems are greater for dogs.

May be restricted to a poor diet

Dogs at home don’t have control of what they eat and some foods disrupt a healthy microbiome.

Often live in crowded spaces

A dog’s environment can affect a dog’s healthy microbiome when new bacteria are transmitted from an infected dog through close contact. Mouth bacteria may be transmitted from dog to dog.

Cannot voice discomfort or pain

Dogs cannot say if they are hurting from a mouth infection. Warning signs of gum disease may be too subtle becoming noticeable only after the disease progresses.

Additionally, factors like genetics and mouth shape can contribute to periodontal diseases in dogs creating more barriers for dogs maintaining clean mouths.

How Clean Is A Dog’s Mouth?

How clean is a dogs mouthDon’t like brushing teeth? When food particles get left behind, they attract bacteria. Bacteria surround teeth, forming plaque almost immediately.

Plaque consists of microorganisms, mainly including:

  1. Bacteria
  2. Fungi

After 24 to 72 hours without brushing, plaque begins to die and harden. The hard material is called tartar. If left untreated tartar buildup leads to gum disease.

At least 80% of dogs over the age of three have developed gum disease.

Gum disease is caused by an overgrowth of plaque most often due to poor cleaning. So, the good news is that gum disease in dogs is highly preventable!

Periodontitis (gum disease) is one of the most common diseases in dogs. Due to tartar overgrowth, it causes severe inflammation and chronic swelling of gum tissue.

A dog’s mouth is home to a variety of bacteria but are dogs’ mouths cleaner than humans? Because dogs lick everything, harmful bacteria may end up in a dog’s mouth. Additionally, causes of kennel cough in dogs may be bacterial or viral.

Bacteria TypeCharacteristicsZoonotic Transmission?
PasteurellaA bacteria found in dog mouths may cause illness if conditions are right. Possible pasteurella infection in dogs include infection of the:

Ear, Eye, Joint, Nasal, or sinus. Additionally, it may affect the brain and chest cavity.


May spread through an open bite or scratch wound, occasionally via saliva.

In humans, it may cause a potentially serious skin infection called cellulitis.

CapnocytophagaFound in dog saliva. Typically does not make dogs sick although it is opportunistic and may infect a body when conditions are right like in a weak immune system for instance.Yes.

Can through dog saliva, bite, or scratch, albeit rarely.

In humans, it may cause illness including sepsis which is potentially lethal.

SalmonellaDogs may carry Salmonella in the digestive tract undetected. While it doesn’t live in the mouth, it will stay on feces from an infected dog.Yes.

If a dog’s mouth comes into contact with infected feces and licks your face, they can transmit salmonella through their saliva to you.

ClostridiumA bacteria found in dog digestive systems. Infection may occur through contact with infected feces. If the bacteria exist in large numbers it can cause inflammation in the dog’s colon, causing severe diarrhea.Yes.

Humans can become infected if a dog’s mouth comes into contact with infected feces and then with a human. Also found in soil dogs pick up.

PorphyromonasThe bacterial pathogen found in dogs’ mouths is primarily responsible for periodontitis, a severe form of gum disease.Yes.

Gum disease-causing bacteria may spread from dogs to humans through close contact.

*While dog gum disease bacteria may contaminate a human’s mouth, it typically won’t cause illness.

CampylobacterBacteria found in the intestines of healthy or sick dogs. May cause diarrhea in dogs. Infection is spread through feces or through contaminated meat.Potentially.

Campylobacter is considered zoonotic, so dog-to-human transmission is possible although it isn’t common.

The microbiome of a dog’s mouth is home to various types of zoonotic bacteria including dog diseases transmitted to humans. Although, infection remains rare. For instance, while viruses are zoonotic, humans have not yet been infected with dog pneumonia.

Is A Dog’s Mouth Cleaner Than A Human?

Is a dogs mouth cleaner than a humans?The average human carries somewhere between 50 million and 100 million bacteria in their mouth and around 200 different species. About 700 different species of bacteria have been discovered in human mouths total.

A dog’s mouth is not cleaner than a human’s, rather a dog’s mouth cannot be compared to a human’s.

A dog’s microbiome is specific to a dog’s biology– it can safeguard against getting sick from dog-specific behaviors like eating raw meat.

If humans decided to eat nothing but raw meat, they’d be more likely to get sick much faster. Raw meat contains bacteria such as:

  • E. Coli
  • Salmonella
  • Yersinia Pestis (plague)

Humans lack sufficient protection against the bacteria dogs took years to develop protection against. Bacteria like those found in raw meat.

But perhaps humans still believe the misconception (that a dog’s mouth is cleaner). Misunderstanding dogs’ oral health needs may contribute to why most dogs fail to receive consistent dental care.

Periodontitis is prevalent in the mouths of both dogs and humans.

Additionally, not every human will prioritize oral health which may extend to loosely monitoring their dog’s oral health as well–and it doesn’t mean owners don’t care. Many dog owners are uninformed about the seriousness of oral health problems in dogs. But bad breath is hard to ignore and may indicate gum disease in dogs.

So, is it true that dogs’ mouths are cleaner than humans?

Dogs and humans host and resist different bacteria. But the amount of bacteria in a dog’s mouth and in a human’s mouth is relatively even.

And when smooching your dog, don’t worry, one mouth may not be more or less clean than the other in any meaningful way.

How Are Dogs’ Mouths Cleaner Than Humans?

Therefore a dog’s mouth isn’t powerful because it’s clean but because it’s sufficiently dirty with the right bacteria. Dog’s have resistance to bacteria that would make most humans sick. Although diseases like Bordetella Bronchiseptica in dogs are severe and very rarely does it infect humans.

Antibacterial dog saliva

Can dog saliva clean wounds? Dog saliva contains healing properties known to protect against infections, including:

  1. Histatin
  2. Nitric acid

Evidence shows that dog saliva contains properties that may promote healing.

It’s fun to think about dogs with inherent healing powers but the antibacterial proteins in dog saliva is no match compared to modern medicine. And before we ask our dog to anoint our next cut or scrape, know that the licking can actually make it worse.

What Animal Has The Cleanest Mouth?

What animal has the cleanest mouth?Asking whether dogs’ mouths are cleaner than humans has been much of the focus but by now we know the popular rumor falls flat. However, some animals in the wild truly have very clean mouths such as the Komodo dragon. Once thought to kill predators using its bacteria-rich mouth, later proved to be false.

The Komodo dragon kills prey with its mouth using straight venom. As for the bacteria found there isn’t a whole lot. In fact, a Komodo Dragon has so little bacteria in its mouth that it’s not enough to infect an animal that is injured or sick.

How To Keep Your Dogs Mouth Clean

How to keep your dogs mouth cleanA clean dog mouth requires:

  1.       Good oral hygiene via brushing, flossing, dental checkups
  2.       A diet low in sugary foods and unhealthy starches

Dogs that develop dental problems will experience symptoms such as:

  • Bad breath
  • Swollen or bleeding gums
  • Brownish-yellow plaque buildup
  • Tartar
  • Too much drooling
  • Avoiding food

Below are the dog breeds that commonly suffer from periodontal diseases.

A dog’s genetic structure can make it more difficult to maintain a clean mouth however it isn’t impossible to do.
Breed physical characteristicsProblematic physical features Why is oral health challenging?Dogs that may need extra oral care
Breeds with a squashed face and short snoutAn uneven bite, overcrowded teeth, facial structure causes oral problemsTeeth easily trap food causing bacteria buildup, risk of gum diseasePugs, Shih Tzus, Bulldogs, Boston Terriers.
Toy breeds prone to snaggle teethBaby teeth grow on top of adult teeth may cause an uneven biteTeeth easily trap food and debris leading to gum diseaseYorkies, Maltese, Poodles, Pomeranians
Small breeds with small mouthsSmall mouth, overcrowded teethCrowded teeth easily trap food, causing plaque buildup and leading to gum diseaseChihuahuas
Breeds with elongated bodiesLong and narrow snoutThe shape of the snout is a risk for developing periodontal pocketsDachshunds, Collies
Large breeds prone to gum disordersOften suffer from overgrown gumsOvergrown gums are at risk for gingival hyperplasiaBoxers, Great Danes, Mastiffs

Any type of disturbance to the composition of mouth bacteria risks leaving it vulnerable to outside germs that may be harmful. Factors that influence the composition of microorganisms in dogs’ mouths include:

  • Age
  • Diet
  • General health
  • Changes in the environment

For instance, when a dog’s health begins to decline as they get older, some mouth bacteria may move into the internal organs and cause greater health problems so keeping teeth clean through good dental hygiene habits is vital.

The periodontal disease raises the risk for dogs developing heart disease. A dog breathing heavy may indicate heart problems.

Also, a diet high in sugary foods can be detrimental to a dog’s mouth. Certain foods are high in complex carbohydrates and easily stick to a dog’s teeth. Avoid foods including:

  • Wheat
  • Treats that have fillers
  • Dental sticks especially those which are starch-based (potato or rice)

There are ways for owners to manage the dental health of pet dogs including investing in a dog toothbrush and brushing the dog’s teeth regularly.

Additionally, regular appointments with a dental veterinarian should start when dogs are healthy rather than waiting for dogs to show symptoms. Deep cleaning on top of daily brushing may be necessary to prevent plaque buildup and tartar formation. Some breeds (mentioned above) may require deep cleaning twice a year to maintain a clean mouth while other breeds do fine with an annual treatment.