You’ve probably heard the old saying: “A dog’s mouth is cleaner than a human’s.” It’s a phrase often tossed around, usually to justify a slobbery kiss from a furry friend. But is there any truth to it? The short answer: not exactly. While both humans and dogs carry bacteria in their mouths, they’re not directly comparable, and each has its own unique microbial environment.
Let’s break down the myth and explore what science has to say about canine and human oral hygiene.
Where Did the Myth Come From?
The idea that a dog’s mouth is cleaner than a human’s likely originated from observations that dogs often lick their wounds, and those wounds sometimes heal well. People may have assumed that their saliva had healing properties or was somehow more sterile. In reality, there’s no scientific evidence to suggest that dog saliva is cleaner or safer than human saliva.
Different Species, Different Bacteria
The truth is, both dogs and humans have mouths full of bacteria, but they’re different types of bacteria. Dogs carry around more than 600 different types of oral bacteria, and humans carry about the same number—just different strains. While many of these bacteria are harmless (and even beneficial), some can be dangerous in the wrong context.
In humans, bacteria like Streptococcus mutans contribute to cavities and gum disease. Dogs, on the other hand, don’t get cavities as often, but they’re prone to periodontal disease due to different bacterial activity and mouth anatomy.
Some of the bacteria in a dog’s mouth—such as Capnocytophaga—can be harmful to humans, especially those with weakened immune systems. While rare, infections transmitted from dogs through bites or saliva can cause serious health issues in certain people.
Is Dog Saliva “Healing”?
It’s true that dog saliva contains enzymes that may help prevent infection in minor wounds—in dogs. However, that doesn’t mean it has the same effect on humans. In fact, letting your dog lick your cuts or scrapes can expose you to bacteria that don’t belong on your skin or in your bloodstream.
If your pet licks a wound, it might actually slow down healing or cause an infection. Medical experts strongly advise against letting dogs lick open wounds on humans.
Oral Hygiene Differences
Another major factor to consider is oral hygiene habits. Most humans brush their teeth at least twice a day and see a dentist regularly. Dogs, on the other hand, may only get their teeth brushed occasionally (if at all) and may develop tartar and plaque buildup by the age of three. So from a cleanliness standpoint, humans usually have the upper hand, assuming good dental hygiene.
While a dog’s mouth isn’t necessarily “dirtier” than a human’s, it’s definitely not cleaner. The bacteria in a dog’s mouth are different, and in some cases, more dangerous to humans. That doesn’t mean you should stop loving on your pet, but you should be mindful about sharing food, allowing face licks, or letting your dog lick wounds. So next time someone says a dog’s mouth is cleaner than a human’s, you’ll know it’s a myth—just one that’s been barked up the wrong tree!
About the Practice
Put the myth to bed and make sure your mouth is cleaner than a dog’s by investing in preventive dental services with Forever Young Dentistry Bayside! Our highly experienced dentists are experts in their field with a focus on your comfort. We take safe, detailed digital X-rays, so there’s no messy, sticky cleanup involved. We’ll make sure you’re in good oral health and help maintain your teeth with a thorough cleaning. Head on over to our website to schedule your appointment or call (586) 277-0080.