Is a Dog’s Mouth Cleaner Than a Human’s? Vets Weigh In

There is a long-held belief that a dog’s mouth is cleaner than a human’s mouth. But is this really true? We asked experts to myth bust.

May 21, 2024·6 min read
Calendar Icon
Is a Dog’s Mouth Cleaner Than a Human’s? Vets Weigh In

If you’ve ever shared a bite of food with your dog or let them give you a kiss directly on the lips, you aren’t alone. And maybe, like many of us, upon seeing appalled faces or hearing revolting comments, you’ve said, “It’s fine! Their mouths are cleaner than ours are!” 

We hate to break it to you, but that may not necessarily be true. In reality, comparing our mouths with dogs’ mouths is tricky. There are some similarities, but there are also a number of differences to take into account. So, before you go sharing a bowl, let’s dive into your pup’s mouth (and the germs found there) a little deeper. 

Are Dogs’ Mouths Clean? 

Considering the things your dog licks, eats, or chews on — and that’s just the ones you’re aware of — it likely won’t come as a shock to hear that dogs’ mouths aren’t nearly as clean as we’d like to believe. 

“A dog’s mouth has bacteria in it just like ours do — some species that are the same and some that are different,” says Dr. Chyrle Bonk, who has practiced in a mixed animal clinic for over 10 years. “While we both have bacteria, it’s important to mention that some dogs will eat things in their environment that aren’t considered food (feces, rotting food, etc.) which can definitely make their mouth less clean.” 

But when it comes to being “clean,” what exactly qualifies for our canine friends? 

According to Dr. Kathryn Dench determining if a dog’s mouth is clean can include “multiple factors like the absence of significant bacterial buildup, tartar, dental disease, and odor.”  

Dr. Dench explains that a dog’s mouth isn’t automatically considered dirty or unclean because it has bacteria in it. In fact, some bacteria are good. “Just like in humans, bacteria are crucial to maintaining a healthy mouth,” she says. “But bacteria become problematic if the growth isn’t balanced or controlled, leading to dental disease or infections.” 

There are other factors, such as a dog’s breed and age, that can play a role in overall dental hygiene too: 

Older dogs often show more signs of dental disease due to prolonged exposure to bacteria and poor oral health habits. Over 80 percent of dogs over the age of 3 are suffering from some type of dental-related issue.  

Small breeds like Chihuahuas and Dachshunds tend to be more prone to dental issues [1]. Overcrowding of teeth in their mouths can lead to increased plaque buildup.  

Bacteria in a Dog’s Mouth vs. a Human’s Mouth 

While we have a similar number of bacteria in our mouths compared to dogs (615 species versus 600 species, respectively), there are different types of bacteria in each.  

This makes things tricky when it comes to comparing the two — like trying to compare apples to oranges. 

One bacterial family called Porphyromonas, however, can be found in both human and canine dental environments, specifically the two strains P. gingivalis and P. gulae. These bacterial strains are major pathogens that may lead to periodontal disease in both dogs and their owners. 

Most of the bacteria found in your dog’s mouth, however, are not zoonotic (meaning they can’t be spread between animals and people). The ones that do cause illness in people are usually transmitted by bites rather than slobbery kisses. In other words, your chance of catching something if your dog licks you is extremely low! 

However, to reduce the risk, pet parents should employ appropriate parasite prevention, vaccination protocols, and dental hygiene in their dogs. 

Is My Dog’s Mouth Actually Cleaner Than Mine? 

No, a dog’s mouth isn’t cleaner than a human’s.  

“If we look at the mouth ecosystem as a whole, dogs’ mouths are not inherently cleaner than human mouths,” says Dr. Dench. “This common myth stems from the fact that human bites are often more dangerous than dog bites due to pathogens like Staphylococcus aureus and Streptococcus species, which can lead to severe infections like cellulitis and septicemia. While dog bites can also transmit bacteria like Pasteurella and Capnocytophaga, which can cause significant infections, these tend to be less aggressive than those found in human bites.” 

We’re happy to report that the myth is officially debunked. 

You should also keep in mind if your dog has a habit of eating things they shouldn’t — like dirt, cat litter, or other dogs’ feces — it can lead to them contracting hookworms or roundworms which can be transferred to a pet parent if any contaminated saliva is ingested. 

The Importance of Cleaning Your Dog’s Mouth and Teeth 

Even if your dog doesn’t eat garbage or poop, keeping your pup’s mouth and teeth clean is essential for their overall health and wellbeing. As mentioned above, dental issues impact over 80 percent of dogs over 3 years old.  

But at-home dental care can target tartar buildup and keep a dog’s teeth, gums, and mouth healthy. A good teeth cleaning can also freshen breath – making those doggie kisses much more tolerable. 

How to Clean Your Dog’s Mouth and Teeth 

A typical dental routine for dogs usually includes the following: 

  • Routinely brushing with a dog-safe toothbrush and toothpaste. Vets recommend brushing at least once per day for 30 seconds on each side of your dog’s mouth. 
  • Having dental assessments done at your dog’s yearly veterinary checkups. 
  • Opting for full dental cleanings performed by your veterinarian when recommended.  
  • Utilizing at-home dental care products to help freshen bad breath and target tartar buildup 
  • Choosing dental toys that are safe for dog teeth, like rubber nubby bones meant to imitate the act of brushing their teeth and gums 
  • Avoiding hard bones, like antlers or raw bones, that could potentially crack or break your dog’s teeth 

Learning about your dog’s dirty mouth may cause you to hesitate next time they come in for a smooch. But establishing good dental care habits at home can keep your dog’s mouth clean, healthy, and happy.  


  1. O’Neill, D G et al. The Journal of small animal practice vol. 62,12 (2021): 1051-1061. doi:10.1111/jsap.13405
Emily JohnsonE

Emily Johnson

Emily Johnson has always been a lover of animals and all things content. She’s grown up with numerous cats and dogs, along with riding and owning horses for 20+ years, and wanted to make animals a vital part of her life and career. Emily currently resides in North Carolina with her fiancé and their rescue dog and two cats. You can typically find her at her desk (with a cat in her lap and a Diet Coke in hand), on a nature walk with her pup, or reading a book after work.

Related posts


Join Our Mailing List For Pupdates & Access To Special Discounts!


Pay Securely With

Visa card
American Express card
Disover card
Google pay
Apple pay

© 2024 PetLab Co.

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.
*In Amazon Pet Health Category in 2022
Back to top button