Is Dog Mouth Cleaner Than Humans? What to Expect

The age-old debate over whether a dog’s mouth is cleaner than a human’s has intrigued pet owners, veterinarians, and curious minds for generations. 

You’ve probably heard the myth that a dog’s mouth is a germ-free paradise, but is there any truth to this popular belief? 

In this article, we’ll dig deep into the science, myths, and realities behind the cleanliness of a dog’s mouth compared to a human’s and explore the implications for both our furry friends and us.

A Myth Rooted in History

The notion that a dog’s mouth is cleaner than a human’s dates back centuries. Ancient civilizations, such as the Egyptians, believed in the healing properties of dog saliva and even used it to treat wounds. 

However, it’s essential to remember that these beliefs were based on limited scientific knowledge and superstition rather than concrete evidence.

Microbes in the Mouth

To determine whether a dog’s mouth is cleaner than a human’s, we need to examine the microbial composition. The human mouth is home to over 700 different species of bacteria, viruses, and fungi. 

Some of these microorganisms are beneficial, while others can cause oral health problems. Dogs also have a complex oral microbiome, although it differs significantly from that of humans.

The Oral Microbiome: Humans vs. Dogs

In recent years, researchers have made substantial progress in understanding the oral microbiomes of both humans and dogs. 

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Human mouths contain bacteria that are specific to our species, such as Streptococcus mutans, which is a major contributor to dental cavities. 

In contrast, dogs have their own unique set of oral bacteria, like Porphyromonas gulae, which plays a role in periodontal disease.

Canine Oral Hygiene

When it comes to oral hygiene, dogs can’t brush their teeth or use mouthwash like humans. Instead, they rely on chewing, licking, and their natural saliva to maintain their oral health. 

While a dog’s saliva does contain enzymes that help break down food and may have some antibacterial properties, it’s not a magic elixir that keeps their mouths perfectly clean.

Comparing Bacterial Loads

One way to assess the cleanliness of a dog’s mouth compared to a human’s is by comparing the bacterial loads. 

Research has shown that dogs can carry fewer harmful bacteria in their mouths than humans, but this doesn’t necessarily make their mouths cleaner. Dogs have evolved to handle different types of bacteria, and their mouths are adapted for this purpose.

Zoonotic Diseases

Another crucial aspect to consider is zoonotic diseases, which are diseases that can be transmitted between animals and humans. While it’s rare for dogs to transmit diseases through their saliva, it is possible. 

For example, Capnocytophaga canimorsus is a bacteria commonly found in the mouths of dogs that can cause infections in humans, especially those with weakened immune systems.

The Impact of Diet

Diet plays a significant role in the oral health of both humans and dogs. What we eat affects the composition of our oral microbiome and can lead to dental problems if we consume sugary or acidic foods regularly. 

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Similarly, the type of food a dog eats can influence the balance of bacteria in their mouths. High-quality dog food and dental chews can help promote better oral health in our canine companions.

Dental Care for Dogs

To maintain a dog’s oral health, regular dental care is essential. This includes brushing their teeth, providing dental chews or toys, and scheduling professional cleanings with a veterinarian. 

Neglecting dental care can lead to periodontal disease, which can be painful for dogs and potentially impact their overall health.


In the end, the question of whether a dog’s mouth is cleaner than a human’s is more complex than a simple yes or no. 

While dogs may carry fewer harmful bacteria and have evolved to cope with their unique oral microbiome, it doesn’t mean their mouths are inherently cleaner. 

Good oral hygiene practices for both humans and dogs are crucial to prevent dental issues and reduce the risk of zoonotic diseases.

So, the next time you share a smooch with your furry friend, remember that their mouth may not be as pristine as the age-old myth suggests. 

Instead, focus on providing proper dental care and hygiene for your dog to ensure their oral health is the best it can be.

In conclusion, the cleanliness of a dog’s mouth compared to a human’s is a multifaceted topic with scientific, health, and practical implications. 

By understanding the complexities of both human and canine oral microbiomes, we can make informed decisions about oral hygiene and care for our pets while debunking the myths that have persisted for generations.