Are Dog Mouths Cleaner Than Human Mouths?

Have you ever heard that a dog's mouth is cleaner than a human mouth? Someone may have said this while their dog was passionately licking your face or eating off of your plate in a well-meaning attempt to make you feel better. Well, sorry: a dog's mouth contains just as much bacteria as your mouth does.

The Same, But Different

Both dog and human mouths are hosts to hundreds of kinds of bacteria. The good news? Most of those bugs are species-specific, which means that Fido's germs won't survive long in your mouth, and vice versa. Still, because there's only about a 16 percent overlap of oral microorganisms between dogs and humans, so there's no such thing as comparable, objective "cleanliness" with regards to their mouths.

How To Stay Safe From Dog Germs

While there isn't a lot to worry about, if you want to protect yourself from icky stuff in your dog's mouth, there are a few things you can do. Keep your dog from picking up extra bacteria, such as that from trash cans, rancid food, and wild animals. You can also keep yourself healthy by keeping your dog healthy—that means proper parasite control and regular teeth cleanings. 

Is there something you're curious about? Send us a note or email us at editors (at) And follow Curiosity on Facebook, Instagram and Twitter.

West highland white terrier brushing teeth in shower.

Watch And Learn: Our Favorite Content About Dogs

Should You Let A Dog Lick Your Face?

Key Facts In This Video

  1. Dog mouths are not cleaner than human mouths, as both mouths contain species-specific bacteria. 00:43

  2. One 2015 study found that oral-to-oral transfer of bacteria from dogs to humans can cause gingivitis and periodontal disease. 01:14

  3. You're more likely to catch an infection by swapping saliva with another human than with a dog. 02:37

Why Do Dogs Eat Grass?

Your Dog Probably Loves You At Least As Much As Food

Written by Curiosity Staff March 2, 2016

Curiosity uses cookies to improve site performance, for analytics and for advertising. By continuing to use our site, you accept our use of cookies, our Privacy Policy and Terms of Use.