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Should I Be Letting My Dog Lick My Face?

Advice from an emergency animal technician, a veterinarian and a professor of infectious diseases

Parenting a pet, no matter what kind, can be a frustrating and bewildering experience. Animals can’t tell you what they want and need (directly, at least), so we’re here to help you answer any questions you have about your favorite companion — whether they be furry, slimy, feathered, scaly or anything in between — with insight from the experts. This is “Basic Bitch,” an advice column for pet parents who just want the best for their best friend.

The Very Basic Concern

I treat my dog like I would my own baby child, supplying him with plenty of kisses around the muzzle and letting him slobber on my face in return. But I was scrolling through my news feed the other day and stumbled upon a story about a guy who contracted a serious illness from dog saliva. He had to have several limbs amputated, as well as the tip of his nose and some of his upper lip! 

Naturally, I got pretty scared, so now whenever my dog comes over to give me kisses, I push him away from my face. It breaks my heart, because he looks so sad and confused. I want to give him kisses again, but that story petrified me. I’d always heard that dog mouths were super clean, so I have no idea what to believe anymore.

Basically: How clean are dog mouths, anyway, and how concerned should I be about contracting a sickness from their smooches?

The Expert Advice

Tony Johnson, emergency and critical care veterinarian and Minister of Happiness for the Veterinary Information Network: Dog mouths are about as clean as your average human mouth. It’s where the world enters your dog’s body, so there will always be some grunge there. The old bit about dog saliva being somehow cleaner than your mouth is utter bohunk, but it’s not necessarily worse, depending on the dog, their diet, their overall health, dental disease, if Jupiter is in retrograde, etc.

The bacteria in these cases [where people get sick] is one called Capnocytophaga, which isn’t one I see come up on routine cultures. Capnocytophaga isn’t an E. Coli, nor a Staphylococcus. It’s not your everyday stock-and-trade kind of bacteria. Everything in life has a modicum of risk, but these cases that you see in the media are incredibly rare events that are super serious for the individuals, and unfortunately, they make good copy, which makes good clickbait. But they are very, very rare, so the average pet owner doesn’t need to be concerned. I have two dogs, and they lick me frequently. The public safety people would be like, “Every time you come in contact with a dog, wash your hands,” which we all know isn’t possible in real life.

Where I think the level of concern would probably be a little higher is with people who have abnormal immune systems — people who are immunosuppressed, who were transplant recipients, who have HIV and things like that. Hopefully, those people have physicians who talked to them about the risks of pet ownership, but those are people who need to be more on guard.

But if you never want to risk this, then don’t get a dog. Instead, get an air fryer or something and be lonely and sad. If you want to have a dog, you have to accept some very, very, very, very, very, very, very, very, very tiny risk and maybe wash your face after doggy kisses. Just practice basic hygiene.

TL;DR: These people were very, very, very, very, very, very, very, very, very, very unlucky, so don’t worry too much.

William Schaffner, professor of infectious diseases at the Vanderbilt University School of Medicine: All of we mammals have lots of bacteria in our mouths, so the idea that dogs have cleaner mouths isn’t correct.

In particular, this one kind of bacteria, which is more frequently found in dog mouths than in cats — it has this long monicure, Capnocytophaga canimorsus — is a very rare cause of infections in humans. The average doctor is’t familiar with this bacteria, but we infectious disease specialists know about it. What will happen is, more often with a bite or a lick on some sort of injury where there’s already been a break in the skin, this bacteria will be transmitted from the dog to us, and then idiosyncratically gain access to our bloodstream. That’s what happened to this chap.

This bacteria then begins to circulate in the bloodstream and multiply. It doesn’t want to make you sick, but it finds itself in this ecological niche where it can multiply. Once that happens, it can make you very, very ill — life-threateningly ill, as a matter of fact. It’s capable of producing the illness we call sepsis, which is profound illness: The bacteria circulating in our bloodstream sets off a whole series of both biochemical and immunological reactions, so that our blood pressure drops, our inflammatory system is evoked and the bug can cause damage to our functioning organ systems. So you need an odd series of circumstances to be all lined up for something like this to happen.

We have all kinds of people out there, though. There are people who are blindly indifferent, and then there are people who are obsessively careful. If you’re on the more cautious end of the spectrum, don’t let your dog give you lip-smacking kisses right on the mouth and stuff like that. Clearly, if you have any kind of injuries — sometimes these can be subtle, like when you’ve been working in the yard and get some scratches on your hands or injuries around your nails — if the dog licks those, that might be a point of entry. They never found the point of entry on this man, and they’re just making a reasonable assumption that the pet dog was the source, which is probably right. But we don’t know what it is that the dog did to the person that set him up.

Certainly, if you have any kinds of injuries, keep your distance from the dog until they’re healed, and don’t exchange kisses with the dog. 

Jerry Klein, chief veterinary officer at the American Kennel Club: Dog mouths are neither cleaner, nor dirtier than a human mouth — they just have different percentages of types of bacteria. Dogs seem to have more gram-negative bacteria in their mouths, which are usually more commonly seen in the gastrointestinal tract. This occurs because dogs tend to lick and sniff areas exposed to feces, like the rectal area, contaminated ground and soil. Humans, in comparison, tend to have more gram-positive bacteria in their mouths.

Pathogens live in saliva and can be transferred to people through direct or indirect contamination: Via a dog licking an open wound, mucous membranes, the eyes, nose and mouth or by people having saliva (or fecal remnants) on their fingers or hands and then touching their noses or mouths. Dog licks may also transfer bacteria and parasites — roundworm eggs, for example — to children. There can also be a transmission of species of bacteria causing periodontal disease in dogs between dogs and people.

Dog saliva may produce allergies in humans, too. Dog saliva contains at least 12 different allergy-causing protein bands. When dogs lick their fur, that saliva dries and these proteins become airborne. Researchers who conducted a study concluded that dog saliva has greater potential as an allergen source than dog dander.

Exposure to pathogens coming from a dog’s saliva is concerning to all, but not necessarily panic-worthy. The recent story of a man contracting and dying from infection by Capnocytophaga canimorsus, a bacterium commonly found in the mouths of dogs and cats, is extremely rare, but unfortunately possible.

The safety of dogs licking faces is more concerning for infants and children, as they commonly put their hands in their noses and mouths, as well as those immunocompromised members of a family or guests. A dog licking the faces of children shouldn’t be encouraged. As always, good hygiene should be practiced by all, but especially stressed to higher risk groups of infants, children and immunocompromised people. They should wash their hands after touching a dog and refrain from having a dog lick their faces.