Why do dogs lick other dogs’ mouths?

There are several behaviors a dog exhibits in everyday situations that leave us busy watching for signs, so we can distinguish whether his behavior in a particular instance is aggressive or friendly. One such behavior is dogs licking other dogs’ mouths. Any time your dog interacts with another dog, you should pay attention, and your dog licking or being licked in the mouth by another dog is no exception.

You should pay special attention to the reaction of the recipient of the licking, watch both of their body languages, and consider the context — the setting and current situation. In other words, what is happening at the time, or what has just happened — e.g., Is there chaos or calm, and has provocation of any kind taken place?

Why do dogs lick other dogs’ mouths?

When a dog licks another dog’s mouth, it can be either a good sign or a bad one, and the only way to tell is to watch the dogs’ interaction and evaluate the context of the circumstances at the time, as well as take into consideration what you know about the dogs’ temperaments. 

There are various reasons why dogs lick other dogs, and there are various reasons why dogs lick other dogs in their mouths as opposed to their ears or their “privates”, while puppies essentially have one reason for licking other dogs in the mouth, and it’s usually their mothers.

Puppies lick their mothers in the mouth as a sign of need.

With wild dogs, a puppy will lick her mother’s lips once she comes home from a hunting trip. She will have a stomach full of sustenance, and the puppy’s licking is a signal for her to regurgitate a little of the food she has already digested, so her hungry puppy can fill her belly, too. It sounds disgusting to us, but for baby pups, it solves the problems of not yet being able to chew and digest large chunks of meat.

With domesticated puppies, once they transition from their mothers’ milk (or any milk) to solid food, licking is a behavior signaling they look up to the recipient as a caregiver — someone they can go to if they need their needs met. The puppy could also simply be trying to get some attention from her mom. Mothers may also lick their puppies in the mouth as a form of affection.

Dogs lick each other in their mouths as a sign of affability or affection.

It is a dog’s way of carrying on a conversation like you would do with another person. If your dog is licking another dog in the mouth, she is probably attempting to bond with friends or communicate with friends she’s already made.  Licking releases endorphins in dogs that make them feel good, so don’t be surprised that it is a common behavior of dogs.

When dogs are friendly, licking each other in their mouths may be a sign that they are looking for someone to play with. If your dog wants to play, she may be licking just to say — Will you please play with me?

Dogs lick other dogs to investigate them as they relate to themselves.

Dogs inspect and investigate with their noses and mouths. Whatever information they can’t gather with their strong sense of smell, they will gather with their mouths, especially about their food. Dogs licking other dogs’ mouths is a way of figuring out what they’ve been eating to determine what may be nearby for themselves.

Dogs lick other dogs because they can detect many kinds of illnesses.

Dogs have been known to detect various conditions in people, probably due to their abnormally keen sense of smell. They may smell mouth odors caused by periodontitis, or they may smell something turning them on to the trail of various types of cancer.

They can do the same thing in other dogs. If another dog spends a lot of time licking your dog, it may be time to question whether your dog may have a medical issue.

Dogs lick other dogs to show their respect and concede to a higher social ranking.

If a dog wants to show his respect for another dog, she may lick him in the mouth. This is one way of showing deference to a dog they revere as stronger and maybe a social class higher. It lets the other dog know there is no competition, but that he is in charge. The subordinate dog will usually come at the other dog from underneath his chin.

This whole way of thinking is simply an assumption made from carefully taking note of how dogs act around each other. Some dogs act simply proud, some cocky, and some humble toward each other. The assumptions are made because of these interactions.

It is also thought that pheromones play a part in why dogs lick each other in the mouth. The Jacobson organ, also called the vomeronasal organ, in dogs can detect pheromones. It’s an area full of sensory cells in a dog’s nasal cavity. It is known that dogs release pheromones from the labial area (lip area).

Is it OK if my dog licks my other dog’s mouth?

If your dog likes to lick your other dog’s mouth, chances are that it’s nothing to be concerned about. When dogs do this, it’s normally a good sign. It is usually one dog showing another dog respect, affection, or geniality.

The only time it is a bad thing is when the dog who’s being licked has had his fill of it. When this happens, you will normally see signs that he’s had enough and that it’s time to separate them. That’s why it’s important to keep an eye on them whenever they are together and separate them when you cannot do that.

How can I get my dog to stop licking my other dog?

If your dog has a habit of licking other dogs in their mouths, you may feel the need to put a stop to it. If so, here are some helpful hints.

Have the recipient see a veterinarian.

Dogs, with their superb sense of smell, can detect various illnesses. It could be that there is some medical issue yet undetected in the other dog. It could be periodontitis, or it could be a more serious condition, even cancer.

Redirect her to an alternate behavior.

Choose something you can steer your dog toward to make her forget about the other dog’s mouth. The moment you pick up on her intent to lick, use a chosen command such as “stave” to redirect her to another behavior like picking up and chewing on her own toy, not the other dog’s toy or a toy he will be interested in. When she follows your command, use praise and reward.

Watch for signals from the other dog that he’s aggravated.

If the recipient of the licking is trying to turn his head, yawning, trying to pull away, showing his teeth, or growling, he is probably getting aggravated with being licked in the mouth. While it’s the case that most dogs give a warning before they bite, not all dogs do, so if your dog persistently licks the other dog and won’t let up, it’s probably a good idea to separate them.

Also, it is just a good idea to keep dogs separate when you cannot be around to monitor them. You can use closed doors or baby gates to make sure they are safe while you’re away.

Consider a consultation with a dog behaviorist.

If you cannot seem to get a hand on the problem, it may be time to see a dog behaviorist professional. Retraining dogs is what they do for a living, and a behaviorist can probably help your dog.