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Everyone has heard that a dog’s mouth is cleaner than a human’s, but is that really the case? Should we actually be saying no to puppy kisses?

Here’s what you need to know about the cleanliness of your dog’s mouth.

Is Your Dog’s Mouth Cleaner Than Yours?

The short answer is no. Dog mouths are NOT cleaner than our mouths.

In fact, studies have shown that hundreds of unique bacterial species can be identified in the saliva of dogs.

But that doesn’t mean that our mouths are clean. Similar tests in humans have found the same results—there’s bacteria everywhere!

Aside from bacteria, numerous parasites can be present in pet saliva. Both can be transmitted to humans and can cause an assortment of medical conditions.

That’s why your veterinarian may have told you not to let dogs kiss you or lick your face.

How Does a Dog’s Mouth Get Dirty?

Many different things pass through a dog’s mouth, including toys, hair, dirt, feces and food. All of this can be considered normal for a dog. 

Dogs use their mouths for everything:

  • Removing debris from their coat or skin

  • Scratching an itch

  • Licking wounds (yours or their own)

  • Picking up toys

  • Eating and drinking

  • Expressing affection or emotion

Although licking is one major way that dogs clean themselves, wounds and surgical sites can become infected if the dog is allowed to lick them.

What Bacteria Lurks in Your Dog’s Mouth?

Every dog’s mouth has bacteria in it.

The type and amount of bacteria in a dog’s mouth is greatly impacted by the degree of dental disease a dog has. This is because a dog’s teeth can have plaque and biofilm that builds up over time.

Other factors that contribute to bacteria in a pet’s mouth include diet, hygiene, genetics and environmental exposure. 

Some other types of bacteria that you might find in a dog’s mouth include:

Pastuerella is a normal inhabitant of a dog’s mouth that can cause skin and lymph node infections and sometimes, more severe infections. People can be exposed to pastuerella if they allow dogs to lick their wounds or through a dog bite.


Bartonella henselae is a bacterium that is transmitted to dogs from infected lice, ticks and fleas via their feces. Although it can be transmitted to people through cat scratches, it’s unknown whether dogs can transmit infection to humans, according to the Centers for Disease Control and Prevention.


Salmonella, E. coli, Clostridia and Campylobacter are intestinal bacteria in pets that can cause severe intestinal disease in humans. Pets can be free of symptoms yet pass these bacteria in their feces. Most human infection is generally due to oral contact of hands contaminated by the pet’s feces or fecal residue. Because pets lick their anus, these bacteria can also be present in the mouth. So letting a dog kiss you is a potential route of infection from pet to human. But there is little proof that this is actually a major means of transmission.

Can You Get Parasites From Letting Your Dog Kiss You?

Dogs are hosts for many parasites, and they may have them in their intestines but show no signs of illness.

Parasite eggs passed through a dog’s feces can infect humans. So if a dog licks their anus and then a person’s face, there’s a chance the person could contract the parasite.

With most parasites, this type of infection isn’t very likely, though, because the eggs must mature first to be able to infect humans.

But two single-celled parasites, Giardia and Cryptosporidium, are immediately infective and could be transmitted to you if your dog licks your face.

How Likely Is It for Humans to Get Sick From Dog Kisses or Licking?

For most people, accepting kisses from dogs will not hurt them. However, in very rare cases, germs in pets’ mouths have caused debilitating disease in humans, and even death.

In 2019, a woman from Ohio had a rare but debilitating bacterial infection that experts suspect occurred after a family pet licked a small cut on her. The infection became so severe that doctors performed limb amputations to save her life.

However, the susceptibility of a person to the bacteria in a dog’s mouth depends on a variety of factors, including the immune status of the person and the level of exposure.

Those who are immunocompromised include people who are going through cancer treatment or are infected with immunodeficiency virus, as well as the very young or the very old.

You can avoid getting sick by following these tips:

  • Wash your hands adequately after picking up after your dog.

  • Take your pet for fecal examinations and administer dewormers.

  • Keep your dog on flea and tick protection.

  • ALWAYS have a doctor check out bites or scratches from dogs.

  • Don’t let your pet lick your wounds or give you kisses.

  • Routinely wash items that your pet’s mouths and bodies touch.

By: Dr. Monica Tarantino, DVM

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