Why Your Dog Licks You: Should You Let Him?

Written by Dr. Karen Shaw Becker

dog licking boys face

Story at-a-glance -

  • Whether or not you appreciate it when your dog licks your face, have you ever wondered why dogs lick?
  • There can be several reasons your dog licks you, the most likely is that she’s telling you she loves you
  • For healthy people with healthy pets, there’s generally little to no health risk in accepting doggy kisses
  • Infections from dog licks are rare, but it’s wise to remember that dogs’ saliva can harbor pathogens that are foreign and potentially dangerous to humans
  • A common sense approach to preventing illness from a dog lick includes practicing good hygiene and covering any open cuts, sores and skin abrasions until they’re healed

Dogs lick. It’s what they do. Some dogs do more of it than others, but with the proper motivation, they all do it. Even if you’re not a big fan of slobbery doggy licks, have you ever wondered why they do it? When dogs lick our faces, are they “kissing” us, or is something else going on?

According to veterinary behaviorist Dr. Wailani Sung, dogs’ face-licking behavior probably evolved from their wolf ancestors. (Warning: If you already have an aversion to face licking, the following will definitely seal the deal for you.) Wolf pups lick the mouths of adult wolves to trigger regurgitation of partially digested food. It’s part of the weaning process in which puppies transition from sucking their mother’s milk to eating partially digested food and finally, to eating solid food.1

Licking behavior can also occur as part of grooming, says Sung, and if your dog can’t reach your face to “groom” you, he may lick something closer to him such as your hand or leg.

Some dogs will lick a complete stranger’s face as an act of appeasement if they for some reason feel threatened by the person. Also, “When dogs lick the face of children,” says Sung, “it can be a sign of affection, appeasement or simply the act of cleaning food residue off their face.”

For Most Domestic Dogs, Licking Is an Affectionate Gesture

According to world-renowned dog training expert Victoria Stilwell, submissive members of a wild dog pack often lick the more dominant members in an important gesture that helps maintain social harmony within the group.2 However, with most domestic dogs, licking is simply a sign of affection.

“Licking releases pleasurable endorphins which give dogs a feeling of comfort and pleasure — like the feeling people get when they are biting their nails — it relieves stress,” says Stilwell.

If your dog is a bit overly enthusiastic with his licking or if you prefer that he not lick your face, she offers this recommendation:

“If your dog's licking is purely a sign of affection, one way to decrease this is to ignore the licking. Licking never gets attention. If your dog licks you, then you immediately stand up and walk into another room. You want to teach your dog that licking means the person will leave the room. When you pet your dog, if he starts to lick, the petting stops and you walk away. With repetition the licking will stop.”

I would add that you should always do this from a loving place, keeping in mind that your dog is expressing his affection for you in one of the few ways he’s able to.

Are Dog Kisses a Health Risk?

It’s a myth that dogs’ mouths are cleaner than the average human's. In fact, it defies common sense! Dogs' mouths are overflowing with all kinds of bacteria, all the time. Think about it: your dog uses his mouth to do many of the same things you do with your hands … right before you wash them.

Dogs also lick their backsides, sniff the rear-ends of other pets, sample poop, pick up dead animals in their mouths, shove their noses into dirt, lick shoes, chew on socks and underwear — you get the idea.

This doesn’t mean you should push your dog away when he tries to lick you, but it’s important to be aware that her mouth might at times harbor harmful bacteria, so it's a good idea after a slobbery pooch smooch to wash up with soap and water, especially if you’re immunosuppressed.

Fortunately, our skin is designed to provide an effective barrier against potential pathogens in dog saliva, and if necessary, our immune system can mount a protective defense as well. However, if there’s a break of any kind in your skin and your pet licks the area, in a worst-case scenario it can be very serious.

Capnocytophaga Canimorsus Bacteria

According to Dr. Sung, during 2018 there were 12 reported cases of human sickness caused by a type of bacteria found in both dog and cat saliva called capnocytophaga canimorsus.

The Centers for Disease Control (CDC) estimate that up to 74 percent of dogs and 57 percent of kitties have capnocytophaga in their mouths.3 And while the bacterial strain is harmless to pets, it can cause serious problems for people with a compromised immune system who are exposed to it.

The bacteria must enter the skin through an open wound, such as a cut or bite or abrasion, and the dog (or cat) must have a relatively high concentration of the bacteria in his saliva.

Several years ago, an Australian woman had a superficial burn on her left foot and her dog licked the burn. She wound up with septic shock triggered by a capnocytophaga canimorsus infection.4 Since this isn’t a bug the human body recognizes, once it entered the woman’s bloodstream, her immune system had a hard time fighting it off.

Antibiotics eventually cleared the infection, but not before the very unfortunate woman lost her left leg below the knee, part of her right foot and all her fingers and toes. More recently, the same strain of bacteria caused the death of a woman and serious injury to a man, both in Wisconsin. According to USA Today:

“The bacteria led to the June 23 death of Sharon Larson, 58, a South Milwaukee woman and the June amputation of the hands and parts of the legs of Greg Manteufel, 48, of West Bend. In 2015, 3-year-old Liam Young of Louisburg had to have his fingers and toes amputated after he developed the same kind of infection.”5

Again, these are worst-case circumstances and incredibly rare, but it’s important to remember that dogs and cats are not humans, and their bodies can harbor pathogens that are foreign and potentially dangerous to our bodies (and vice versa).

Canine Versus Human Oral Bacteria

From 400 to 500 strains of bacteria have been identified in the human mouth, and so far, scientists have discovered around 400 strains in dogs.6 The microbiomes of people and their pets are markedly different, which is why we can be at risk for infection when our dog licks us. Believe it or not, one swipe of your pet’s tongue can leave behind virtually millions of bacteria your body doesn’t recognize, and those bugs have staying power.

“… If you’re licked by a dog,” says bacterial geneticist Floyd Dewhirst, Ph.D. in an interview with National Geographic, “and someone were to take a Q-tip five hours later and rub that spot, they would recover over 50 different species of dog-mouth bacteria.”7

It’s also worth noting that contrary to another popular myth that has floated around for years, pet saliva has zero antibacterial effect in humans. There may be some protective properties in dog and cat saliva, but only for members of their own species.

5 Recommendations to Keep You and Your Pet Healthy

1. Practice good hygiene — Especially if you’re immunocompromised, the very best way to ensure you and your pet don’t swap germs is to wash your hands before and after you handle your dog, and before touching food. Regular and thorough hand washing is a key to avoiding illness, no matter the situation.

If your pup gives you kisses, wash your face (or wherever she licked you) immediately afterward. Also, brush and bathe your dog regularly. A clean dog is more pleasant to be around, and you’ll also cut down on the dirt, allergens and bacteria she brings into the house on her body and especially, her feet.

2. Cover open cuts, sores and abrasions on your skin — The real danger of pet saliva is with people who allow their dog to lick an area of skin that is wounded and could potentially put bacteria into the bloodstream. So if you have any sort of injury to your skin, no matter how minor, either keep it covered around your dog, or don’t allow her to lick you until the wound is fully healed.

3. Treat bites seriously — While bacteria from dog kisses are typically no cause for concern, dog bites definitely are. Immediate treatment is necessary, whether the bite is superficial or more serious. Clean the wound immediately with soap and warm water, rinsing thoroughly.

For superficial wounds, disinfect several times a day with dilute povidone iodine (Betadine) and cover the wound with a clean, dry dressing. Watch for signs of infection, including redness and swelling. If the bite is a deep puncture wound, seek medical attention immediately, as more intensive treatment may be required.

4. Refuse unnecessary antibiotic treatment — Proceed with a great deal of caution if either you or your dog is prescribed antibiotics for any reason unless a culture and sensitivity has been completed, demonstrating it’s the correct choice. If your vet hasn’t identified what antibiotic will be the most effective at treating the infection, he or she is guessing, which is a bad idea.

Frequent and often unnecessary use of these drugs is causing antibiotic resistance in a growing number of bacteria strains. When antibiotics are no longer effective against serious bacterial infections, there can be life-threatening consequences.

5. Consider giving your pet a probiotic — A high-quality probiotic supplement will recolonize your pet’s digestive tract with healthy bacteria, boost her immune system and improve her overall health. This is especially important if she has received antibiotic therapy.