Are Dogs' Mouths Really Cleaner Than Humans'?

Kathy Hawkins

Many people may have heard a myth that dogs' mouths are cleaner than the mouths of human beings. This rumor is likely to stem from the fact that dogs are often seen licking their wounds, which rarely get infected.

A dog with its mouth open. Contrary to popular belief, dogs' mouths are not cleaner than humans'.
A dog with its mouth open. Contrary to popular belief, dogs' mouths are not cleaner than humans'.

However, people who believe that dogs' mouths are cleaner than humans' mouths are greatly mistaken, according to veterinarians who have spoken on the subject. Most humans have a strong belief in good hygiene, and brush their teeth at least once or twice every day. Human mouths rarely come into contact with external bacteria. Dogs' mouths, in contrast, are rarely cleaned in most cases. Dogs also have a tendency to sniff around and eat bacteria-filled waste — including rancid food and feces — whenever they are given the opportunity to do so. Contrary to popular belief, dogs' mouths are far dirtier than the mouths of the typical human being.

Cleaning the dog's mouth with chicken-flavored toothpaste will be an enjoyable experience for the animal.
Cleaning the dog's mouth with chicken-flavored toothpaste will be an enjoyable experience for the animal.

The reason that dogs' mouths rarely infect the wounds that they lick is that their licking has the effect of clearing away the dead tissue, similar to the work a surgeon would do to clean out a wound. Even though dogs' mouths are full of bacteria, dog bites do not usually cause infections in humans because most bacteria in dogs is particular to their species. Therefore, even if the dog is infected with a disease, the human is unlikely to catch it. For this reason, it is not especially dangerous to share food with a dog or to kiss dogs' mouths, though neither option is exactly the most hygienic of decisions.

Unlike dogs, human mouths rarely come into contact with external bacteria.
Unlike dogs, human mouths rarely come into contact with external bacteria.

If you are a dog owner, and would like to make your dogs' mouths cleaner, there are special toothbrushes and toothpaste that you can buy to use on your dog, which will help to get rid of some of the bacteria in your dogs' mouths. Though it may be difficult to get your dogs to open their mouths initially, they will calm down once they understand what you are doing. Some of the special toothpastes for dogs' mouths come in flavors like beef or chicken — buy one of these, and your dog will soon look forward to his daily teeth cleaning.

Brushing a dog's teeth can help remove bacteria.
Brushing a dog's teeth can help remove bacteria.
Dogs have toys in their mouths much more often than toothbrushes.
Dogs have toys in their mouths much more often than toothbrushes.

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Discussion Comments


Basically, when you let your dog lick your face/mouth, you are touching their genitals.


Everybody, it was just a common belief based on a stupid thing. Real studies have been performed and it is far dirtier. I will not come back to this website so don't reply.


My dog likes to burp in my face. She is a blue-nose pit bull. I'm not sure if this is normal.


A good reason why it's better to have a child kiss you rather than a dog.


Wow this was useful news. No more licking my face, Lucy!


That's because dogs don't live long enough to need a tooth replacement.


i actually found out that in my family i had the same amount of bacteria in each but we do have different types of bacteria.


Say what you want, but if your husband or wife went sniffing behind and eating the neighbor dog's pooh, you would think twice about that next kiss. Letting a dog like you or kiss you is straight up nasty!


I just finished my science fair project on this. the dogs did have more bacteria, but the males, human and dog, had more bacteria than the females. Why?


Since when does acid clean teeth?


dog mouths are cleaner. they have certain bacteria in their mouth that makes them clean.


You all can say what you want, but you have seen where dog tongues have been. Would you eat used toilet paper even if you don't see anything on it? Not me!


my son just got his face licked all over by a dog who's owner claimed he was "clean and brushed regularly", but the next day my son got a face rash that the Doc concluded was caused by the dog's saliva. so don't let your dogs kiss anyone!


Simply put all of you haven't done conclusive studies but this is the easiest explanation: A dog in a good home, where the owners brush the dog's teeth and they keep it away from dirt and poo even when taken for walks will probably have the same level of cleanliness as your average human.

now if i did my study with a dog that's not taken well care of orally, it'll probably be worse than that of a human.

people can also have dirty mouths though. A lot of people bite their nails and if they contain any dirt underneath, usually have higher levels of bacteria which would make their mouths dirtier vs a well kept dog. It's all relative to the dog and person.


Whoever said that dogs have acid in their saliva doesn't have the facts straight. dogs are not flies. they don't have saliva that helps to dissolve their food. If so then it would definitely eat away their teeth.

The outer layers of teeth are not strong enough to withstand and type of acid, (i.e. when we vomit it eats our enamel, citrus acid eats away at our teeth.) If that statement were true why are there all sorts of dog treats with dental assistance added? you can look online and see pics of dogs with rotted teeth so I don't know where you got that statement but you need to give it back.

Those who are doing experiments and saying dogs have cleaner mouths are contaminating the samples with dirty dishes not being sterilized with ethanol. Dogs' mouths are not cleaner than a humans. in fact too much dog saliva causes massive diarrhea for humans. Do the research before you open your mouths with false statements or trying to conduct scientific experiments at home or by yourself while being untrained to handle such experiments. "The truth is out there."


I'm doing a science fair project and i came to the conclusion that my dog actually has a cleaner mouth than my brother does. It was crazy and gross too.


YUP. I did a science fair pro. on this and its a lie. Dogs have dirter mouths than humans' but not by too much. Still safe to kiss though! :)


dogs definitely don't have cleaner mouths in my project. it's disgusting.


I am doing a science project on it right now. I'll post after I'm done!


i did a sci project on it and it turns out that people and dog mouths contain around the same amount of bacteria. all of the petri dishes had around the same kind and quantity of bacteria in them. so you were wrong. i also got second place in the county.


I believe that a dog's mouth is cleaner. I have been doing some research for a project and so far all the people who say dogs' mouths are more bacteria filled base their opinion on what a dog eats. People who say a dog's mouth is cleaner have facts and elaborate conclusions.


I am doing a science fair experiment to see whether a dog or a human has a cleaner mouth and I have come to the conclusion that dogs actually have a dirtier mouth. The dog samples of saliva were horrible, and there were dozens of bacteria types within the petri dish.


The reason dogs' wounds do not get infected is because their saliva contains substances that aid in the healing of these wounds and help prevent infections. Also, it's because dogs eat such "bacteria-filled waste" that their mouths are cleaner; their saliva must contain substances to kill the bacteria they consume. Obviously this takes time, so immediately after consuming bacteria-filled waste, the dogs' mouths are not as clean. As well, dogs and humans are not affected by the same diseases and bacteria (ie. you can't give your dog a cold).


Sorry, anon, but dogs' teeth do rot if you never have them cleaned.


Yeah but dogs salivate more that we do and their saliva has acid which breaks down pieces of food and cleans their teeth so they do have cleaner teeth than humans. When we eat all of our food and don't brush our teeth our teeth rot, dogs eat all kinds of stuff and do you ever take you dog in to get a tooth replacement because of a rotten tooth? I didn't think so.


Anyone who has seen what dogs eat on a regular basis (not their food, but all the stuff they aren't supposed to eat) will think twice about the idea that dogs' mouths might be clean.

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