Are Dogs’ Mouths Cleaner Than Humans’? The Dirty Truth No One Told You

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Your dog just licked your face. Cute, right? And now you’re wondering, “Are dogs’ mouths cleaner than humans’?”

Now imagine that same tongue just cleaned its own butt, tasted a dead squirrel, sniffed three other dogs’ butts, and then gave you a “kiss.” People love to say a dog’s mouth is cleaner than a human’s… but the bacteria tell a much grosser story.

So, are dogs’ mouths cleaner than humans’? Let’s bust this myth wide open and find out what’s really living on that tongue… and why a toilet seat might actually be the safer option.

What’s Really In A Dog’s Mouth?

Let’s start with the obvious: your dog’s mouth is a bacteria party. And not the cute kind.

While humans carry about 615+ species of oral bacteria, dogs have their own ecosystem, including some germs we definitely don’t want in our mouths.

According to the American Kennel Club (AKC), dogs have more than 600 different types of bacteria in their mouths. Sure, the number of germs might be close, but dog mouths carry a very different lineup, and some of it’s not human-friendly.

Here are just a few of the most common (and alarming) bacteria found in dog saliva:

• Capnocytophaga – Rare, but can cause sepsis in humans
• Pasteurella – Linked to skin and soft tissue infections
• E. coli – You know this one… it’s not just from food
• Staphylococcus – Can lead to staph infections
• Salmonella – Mostly present in dog poop, but yep, from dog slobber too
• Porphyromonas gulae – Linked to gum disease in dogs and humans

So when someone asks, “Are dogs’ mouths cleaner than humans’?” just remember: it’s not cleaner. It’s just different. And sometimes a lot riskier.

Can Dog Licks Make You Sick?

Short answer? Yes.

Most of the time, your dog’s slobbery affection is harmless. But under the right (or wrong) conditions, it can lead to some seriously nasty infections, especially if that tongue hits your mouth, an open wound, or your kid’s face.

Here’s when a dog lick can go from harmless to hospital-level dangerous, with a bit more info on those high-risk bacteria:

• Capnocytophaga canimorsus – Rare but deadly; linked to sepsis, meningitis, and limb loss in immunocompromised people.
• Pasteurella – Can cause painful skin and soft tissue infections in humans.
• MRSA & Staph – Dogs can carry these on their skin or in saliva, spreading them through licking.
• Salmonella & E. coli – Dogs can shed these bacteria without symptoms, passing them to humans with one innocent lick.

Dog mouths aren’t necessarily dirtier than human mouths, but they’re full of bacteria that don’t belong in your body.

High-Risk Lick Zones & People

• Mouths, eyes, and open wounds
• Infants and toddlers with developing immune systems
• People with diabetes, cancer, or autoimmune diseases

These areas, especially in kids or people with weakened immune systems, make it easier for bacteria to slip into the body, where they can cause infections that healthy adults might easily fight off.

More On Dog Kisses & Capnocytophaga

It’s got a weird name. But Capnocytophaga canimorsus is the bacteria behind some of the scariest dog lick horror stories out there.

And no, this isn’t fearmongering. It’s rare, but it does happen. So, what is Capnocytophaga?

• It’s a bacteria that lives in the mouths of dogs and cats.
• Harmless to them – but if it gets into your bloodstream?
• It can cause sepsis, organ failure, or death, often within 24–72 hours of exposure.

Multiple cases reported globally have involved severe infections, amputations, or death, even in previously healthy adults.

According to the U.S. Center for Disease Control and Prevention (CDC), Capnocytophaga infections are rare but can lead to serious complications, especially in those with underlying conditions.

So, who’s most at risk?

• People with weakened immune systems
• Older adults
• Those with splenectomy (no spleen)
• Heavy alcohol use may increase vulnerability
• But yes, healthy people have been infected, too

Want to see what can actually happen when this goes wrong? Watch this shocking news video reporting on a woman who lost parts of all four limbs after Capnocytophaga entered her bloodstream through a simple dog lick.

What Happens After A Risky Dog Lick?

In most cases, a dog lick is harmless. But if bacteria like Capnocytophaga sneak into your system, especially through a cut, your eyes, or mouth, here’s how it can go from “no big deal” to “get to the ER” in just a few days.

Day 0: Your dog licks an open cut or sensitive area (like your mouth, nose, or eyes). You probably don’t think twice.

Day 1–2: You might feel like you’re coming down with something, tired, sore, maybe running a low fever. Some people notice redness or swelling around the area that was licked.

Day 3–4: Symptoms get worse:

• Fever spikes
• Muscle or joint pain
• Vomiting or diarrhea
• Confusion or dizziness
• Skin starts changing color (purple/black spots in extreme cases)

Day 5 and beyond: In very rare cases, infection spreads fast, leading to sepsis, tissue damage, or even limb amputation. Hospitalization is required, and recovery can be long.

The good news? These cases are extremely rare, but not impossible, even for healthy adults. If you ever notice symptoms like fever, swelling, or pain near a lick site, see a doctor fast and mention contact with a dog.

So, Are Dogs’ Mouths Cleaner Than Humans’?

Just like me, you’ve probably heard people ask, “Are dogs’ mouths cleaner than humans’?” It sounds science-y. Even comforting. But it’s just not true, and here’s why this myth refuses to die.

Where did this myth even come from? It likely started because dog saliva has some mild antibacterial properties, enough to help them clean their minor wounds.

And because dogs often lick their injuries and still survive, people assumed their mouths must be “clean.”

The truth? They’re just built differently:

• Dogs aren’t cleaner; they’re just tougher. Their immune systems are built to handle the bacteria in their own mouths. Ours aren’t.
• Different ecosystems, different risks. Human mouths are full of bacteria, yes, but most of them belong there. Dogs carry pathogens that don’t belong in human systems and can cause illness.
• Bacteria ≠ Dirtiness. “Clean” doesn’t mean “germ-free.” Both mouths are full of microbes, and it’s about compatibility, not count.

What Makes Dog & Human Mouths Different?

So, if dogs and humans both have hundreds of bacteria in their mouths, why is one riskier than the other? It comes down to evolution, immune systems, and microbiome.

Dogs lick wounds, eat off the ground and out of trash cans, and chew things we’d never touch. Their bodies and mouths evolved to handle a wider range of environmental bacteria, many of which would overwhelm a human immune system.

You can’t really compare a dog’s mouth to a human’s, as they’re entirely different ecosystems. ”It’s like comparing apples and oranges,” says Dr. Colin Harvey, professor of surgery and dentistry at the University of Pennsylvania’s School of Veterinary Medicine.

Dog Mouth vs. Toilet Seat: Which Is Dirtier?

You’ve probably also heard this before: “A dog’s mouth is cleaner than a toilet seat.” That sounds reassuring… until you realize how misleading it is.

According to research, here’s how much bacteria is found on a toilet seat vs a dog’s mouth:

• Toilet seat: Approximately 50 bacteria per square inch.
• Dog’s mouth: Over 600 different bacterial species.

The average toilet seat is cleaned more often than a dog’s tongue and it’s not licking everything in sight. Here’s why the comparison doesn’t hold up:

• Toilet seats are often cleaned with disinfectant – your dog’s mouth? Not so much.
• Toilet surfaces have low bacterial diversity – dog mouths carry a microbiome of potentially harmful organisms.
• Dogs lick trash, dead things, other dogs’ butts, and then your face. Let’s not pretend it’s the same.

So yes, the toilet seat might actually be the safer option, depending on what your dog’s been up to and the toilet seat in question. But honestly? It’s probably best to keep your tongue off both.

Is It Safe To Let Your Dog Lick Your Face (Or Baby)?

It might feel like affection, and let’s be real, it’s adorable. But letting your dog lick your face (or worse, your baby’s) isn’t always a great idea.

Yes, dogs show love through licking. But as we’ve discovered, their mouths can carry bacteria that pose real risks, especially when they land near eyes, noses, mouths, or on someone with a developing or compromised immune system.

Here’s why you shouldn’t let your beloved pups lick yours or your baby’s face:

• Mouth or eye contact increases the chance of bacteria entering mucous membranes
• Minor cuts or acne can serve as open doors for infection
• Toddlers and babies are extra vulnerable as their immune systems are still developing
• Immunocompromised adults (e.g., those with cancer, diabetes, or autoimmune disease) face a higher risk of serious illness

But what about the “aww” factor? I get it. A puppy kissing a baby is heart-melting. That’s why these videos go viral every time…

Even a loving lick can carry Capnocytophaga, MRSA, or E. coli, which are all especially dangerous to babies and at-risk adults.

Bottom line: A kiss on the head? Usually fine. A lick inside your kid’s mouth? Probably not the bonding moment you want.

5 Signs Your Dog Has A Dirty Mouth

Most dog owners don’t check their dog’s mouth until it smells like something died in there. Here are five red flags that your dog’s mouth might be overdue for a clean-up.

1. Their breath smells like trash water. This usually means plaque buildup, bacteria overload, or early gum disease.
2. You see bleeding when they chew. This could indicate gum inflammation or advanced periodontal disease.
3. Their gums look red, swollen, or sore. A bacterial infection or tooth decay could be the reason.
4. They hate having their mouth touched. It’s likely that oral pain, decay, or something stuck between teeth is the culprit.
5. They drool excessively or lick their lips constantly. This often means they’re experiencing oral discomfort or an infection.

VCA Animal Hospitals reports that over 80% of dogs over the age of three suffer from some form of dental disease, and the consequences go far beyond bad breath. Clean mouths = longer lives.

Up next, learn how to prolong your dog’s life by keeping their teeth healthy.

7 Ways To Keep Your Dog’s Mouth Clean

Okay, so your dog’s mouth isn’t exactly a sparkling oasis of cleanliness, but that doesn’t mean you’re helpless.

You can’t make your dog’s mouth sterile (and you don’t need to). But you can make it less gross, less smelly, and less likely to transfer problem bacteria.

Here’s how to clean up that doggy breath:

1. Brush their teeth — yep, they make dog toothbrushes & dog toothpaste (never use human toothpaste)
2. Dental chews & treats — choose vet-recommended brands that reduce plaque and bacteria
3. Water additives — odorless drops that improve oral hygiene. I recommend Oxyfresh’s water additive for pets
4. Professional dental cleanings — your vet can safely remove deep plaque under anesthesia
5. Chew toys — safe rubber or nylon toys help mechanically scrape away buildup
6. Watch their diet — raw meat, garbage, or outdoor snacking raises the risk of dangerous bacteria
7. Regular vet checkups — early signs of oral disease = less risk for everyone

Dogs with clean mouths smell better, have fewer tooth problems, and are less likely to pass funky bacteria onto your hands, face, or furniture.

You can’t make it sterile… but you can make it safer.

Think this “Are dogs’ mouths cleaner than humans’?” infographic could help other dog parents? Save it, share it, or send it to a friend who needs a reminder about keeping those puppy kisses a little cleaner.

6 Common Reasons Why Dogs Lick Us

Not every slobbery kiss is a health hazard, and sometimes your dog’s just trying to tell you something. Dogs lick for all kinds of reasons, and while affection is one of them, it’s not the only one.

1. To Show Affection. Yep, sometimes it really is love. Licking can release endorphins in dogs, making it calming for both of you.

2. To Get Your Attention. If your dog licks you and you always react, even to say “stop!”, they’ve learned it works.

3. Because You Taste Good. Sweat, food crumbs, lotion, or salty skin? You’re basically a walking snack.

4. It’s Instinctual. Puppies lick their moms’ faces for food and comfort. Adult dogs carry that behavior into human relationships.

5. To Comfort Themselves. Licking can be a self-soothing behavior when a dog is anxious, bored, or overstimulated.

6. To Explore. Dogs explore the world with their mouths. Licking helps them “read” your mood, scent, and recent activities.

Licking isn’t always about affection, but it’s usually not random, either.

5 Weird & Cute Dog Saliva Facts

I’ve covered the gross stuff regarding the question on everyone’s lips: “Are dogs’ mouths cleaner than humans’?” So now let’s lighten things up with a few saliva facts that are actually… kinda fascinating.

1. Dog Saliva Has Healing Properties… For Dogs.

It contains enzymes like lysozyme that help fight off some surface bacteria. But it’s no magic cure, and it doesn’t work the same for humans.

2. Some Dogs Drool A Lot & That’s Normal

Breeds like Saint Bernards, Mastiffs, and Bloodhounds are known for waterfall-level slobber. It’s not always a hygiene issue; maybe it’s just a design flaw.

3. Saliva Helps Dogs Taste… Kind Of

Dogs have far fewer taste buds than humans (about 1,700 vs. 9,000, according to the AKC), but saliva helps transport scent molecules to their noses. So yes, they mostly taste with their snouts.

4. Puppies Lick Faces As A Survival Instinct

In the wild, puppies lick their mom’s mouth to signal hunger or get her to regurgitate food. That affectionate lick? It’s part instinct, part habit, part snack strategy.

5. Dogs Can Smell Illness In Humans, Sometimes Through Saliva

Studies show dogs can detect certain cancers, infections, and even blood sugar changes. So, that slobbery lick? Maybe your dog knows something you don’t.

FAQs On Dog Saliva, Cleanliness & Safety

Still wondering, “Are dogs’ mouths cleaner than humans’?” or what’s really going on in your dog’s mouth? You’re not alone. Here are some of the most common questions people ask. If we missed yours, drop it in the comments, and we’ll do our best to answer it.

Are Dogs’ Mouths Cleaner Than Humans’?

No. Dogs and humans both have hundreds of types of bacteria in their mouths, but they’re completely different ecosystems. Many of the bacteria in a dog’s mouth, like Capnocytophaga or Pasteurella, can be dangerous to humans, especially if transferred through cuts or mucous membranes.

It also depends on the dental hygiene practices used by the pet parent. A dog with teeth brushed, eating dental chews, and visiting the vet regularly probably has a cleaner mouth than a stray dog. It also can depend on the dog, as some are predisposed to periodontal disease and other dental issues.

Are Cats’ Mouths Cleaner Than Dogs’?

Yes. Dogs tend to have a higher tendency to lick and chew objects, which can introduce different types of bacteria into their mouths. Conversely, cats have papillae on their tongues that help them clean themselves more efficiently. They also are more likely to groom themselves, which can contribute to maintaining oral hygiene. Bacterial contamination is possible in both cases.

Is It Safe To Let My Dog Lick My Baby?

Generally, it’s not a good idea. Babies have underdeveloped immune systems, and dog saliva can carry bacteria that cause serious illness. A kiss on the back of the head might be fine, but avoid licks near the mouth, eyes, or broken skin.

Can I Get Sick If My Dog Licks My Face?

It’s possible, especially if the lick lands near your mouth, nose, or eyes, where bacteria can enter the body. Healthy adults are usually fine, but if you have cuts, acne, or a weakened immune system, you could be at higher risk.

Are Dog Licks Clean?

No, “clean” isn’t the word to use for describing dog licks. Dog saliva has some characteristics that make humans think it’s clean, such as saliva being antibacterial for them, which is why they often lick their wounds. However, the bacteria in dog saliva can be harmful to humans.

Is It Good For A Dog To Lick Your Wounds?

No! Do not let your dog lick your wounds. Dog saliva has bacteria that can be harmful to humans and can create an infection. Learn more about why dogs lick wounds.

What Happens If A Dog Licks Your Cut?

If a dog licks your wound, there’s a chance that the wound may become infected, so it is best to keep your dog’s mouth away from the area. If you do get an accidental lick, be sure to clean your wound immediately with hydrogen peroxide and then cover it with a bandaid to avoid any further contamination.

What Animal Has The Cleanest Mouth?

Unfortunately, it’s difficult to answer this question because animals have different types of oral bacteria, so it’s like comparing apples to oranges. Perhaps in the future, there will be a way to compare the different types of bacteria. But at this time, it’s impossible to say which animal has the cleanest mouth.

Keep Your Dog Healthier, Happier & Cleaner

Want to improve your dog’s health from the inside out? Start with a high-quality diet that supports their immune system and oral health.

If you’re not already using dog-specific vitamins, now’s the perfect time to boost their daily wellness. While you’re at it, upgrade their sleep with a supportive dog bed that helps reduce joint pain and keeps bacteria-prone spots off your couch.

And if your pup’s kisses come with behavioral chaos, check out our favorite training tools and tips to keep their mouth and manners in check.

Where do you stand on the “Are dogs’ mouths cleaner than humans’?” debate? Would you let your dog lick your face? Or do you have a slobbery story of your own? Drop it in the comments. We’d love to hear about the funniest (or grossest) dog kiss you’ve ever gotten.