Are Dogs’ Mouths Cleaner Than Humans’ Mouths? Not Really.

You’ve probably heard it before. Some dog with bad breath starts licking you and you’re thinking, ew. But their owner insists, “It’s okay—don’t mind the smell. Dogs’ mouths are cleaner than humans’ mouths.” It doesn’t matter that over 90% of owners don’t brush their dog’s teeth every day. No, dogs’ mouths are just naturally that clean. How do they do it? Magic, apparently.

The truth behind the myth

Sarcasm aside, there’s really no truth behind the idea that dogs’ mouths happen to be cleaner than humans’ mouths. In fact, it’s often the opposite. There is nothing that makes dogs’ mouths innately more or less clean than human mouths. The major difference is that the majority of dogs don’t receive the dental care they need, leading to all kinds of dental problems.

Dogs’ mouths have over 600 possible types of bacteria in them. Humans have 615. Dogs may have fewer kinds of bacteria in their mouths (and not by much), but dogs tend to have just as much bacteria. Dogs also have a unique bacteria called P. gulae, which is responsible for the high rate of periodontal disease in dogs.

So no, your dog’s mouth is probably not cleaner than yours.

Keeping your dog’s mouth clean

While infections are rare, it’s still a good idea to keep your dog’s mouth clean. Dental hygiene is just as important for your pup as it is for you!

Proper dental care starts with daily tooth brushing, but that’s it not. You can give your dog dental chew treats. There are dental powder and water additive products that get added to your dog’s food. If these aren’t working, you can also ask your vet about a prescription dental care diet. And be sure to schedule a yearly dental cleaning for your pup

As long as your dog maintains good dental hygiene, you should not have to worry about whether or not your dog’s mouth is clean.

Where does the myth come from?

You might be wondering who started this myth. In short, we don’t really know. But it’s certainly nothing new.

Across cultures in history, the saliva of dogs has been said to have healing properties. Back in ancient Greece, dogs lick wounds and temples and may have even been employed as healers in the army. At least, that’s how the story goes.

Can a dog’s saliva heal wounds?

This answer gets a little bit more complicated. A lick will not cure a wound, but it might help it. 

A lick can get off the dirt and bacteria on top of a wound. This can lower the chance of an infection. But repeatedly licking can harm the wound and end up making things worse.

A study in 1990 found that dog saliva may have slight antibacterial properties and that mothers like their young as a form of medical care. Actually, almost all mammals lick their wounds. This reflex may have once been an evolutionary tool, but saliva has outlived its usefulness. Today there are much better ways to clean a wound. Next time, try some ointment instead of your dog’s tongue.

Tyler Kupcho
Author: Tyler Kupcho

Animal lover, proud husky parent. Writing Intern at

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