Dogs lick each other’s mouths mainly as a form of communication and bonding, and in most cases it’s normal, social behavior rather than something to worry about.

Quick Scoop: The Short Answer

Here’s what that mouth-licking usually means:

  • Leftover puppy instinct (a “feed me” signal from when they were babies).
  • Affection and social bonding (their version of a friendly kiss).
  • Respect or submission toward another dog.
  • A polite greeting and “let’s be friends.”
  • Curiosity about what the other dog has been eating or how they’re feeling.

If both dogs look relaxed and happy, the behavior is typically harmless and normal.

From Puppyhood: The “Feed Me” Signal

In the wild (and still in many domestic dogs), puppies lick their mother’s mouth when she returns from hunting; this action signals her to regurgitate soft, partly digested food for them. As they grow up, the underlying instinct can stick around even when no one is actually vomiting up food anymore.

So when you see a young or even adult dog lick another dog’s mouth, you’re partly seeing an ancient puppy behavior reappearing in a more social, less “gross” context.

Affection, Respect, and Social Rules

In adult dogs, mouth licking turns into a social language:

  • Affection and bonding: Many behaviorists compare it to a gentle social kiss; licking can release feel‑good endorphins in dogs and help strengthen bonds between friends or family pack members.
  • Submission/respect: A lower-status or more timid dog often licks the muzzle of a more confident dog with a lowered body, ears back, soft posture, basically saying “you’re in charge, I mean no harm.”
  • Calming signal: Soft, brief licks can be used to defuse tension, similar to other appeasement gestures like turning the head away or lowering the body.

In packs (or multi‑dog homes), these little rituals help keep the peace and maintain a clear social order.

“Hi, What Have You Been Eating?”

Dogs explore the world with their noses and tongues, so mouth‑licking is also about gathering information.

  • They can sample scent/taste around the mouth to get a clue about where the other dog has been and what they’ve eaten recently.
  • Some trainers and behavior experts suggest dogs may even pick up cues about another dog’s general health this way, such as illness or stress-related scent changes.

So part of the behavior is simple curiosity and canine detective work.

When It’s Playful vs. Problematic

Most of the time, mouth licking is just part of normal doggy interaction, especially if you see:

  • Loose, wiggly bodies.
  • Play bows (front end lowered, rear end up).
  • Wagging tails and bouncy movements.

You should start paying closer attention or gently interrupt if:

  • One dog constantly chases and licks, while the other keeps turning away or trying to escape.
  • The licked dog stiffens, growls, or snaps.
  • The licking becomes obsessive (goes on and on with most dogs they meet).
  • A dog is fixated on licking at another dog’s wounds or sore spots.

Those situations can point to stress, conflict, or even health issues, and it may be worth checking in with a vet or a qualified trainer if you see those patterns.

Mini FAQ (Owner’s View)

1. Should I stop my dogs from licking each other’s mouths?

  • If both dogs look relaxed and are choosing to stay engaged, it’s usually fine.
  • If one looks uncomfortable or the licking is nonstop, calmly redirect them (call them away, offer a toy, or take a short break).

2. Is it a sign of dominance?

  • More often it’s the opposite: the dog doing the licking is being deferential or friendly.
  • Context matters: watch the rest of the body language for clues.

3. Is it hygienic?

  • Dog mouths carry bacteria, so you don’t want them licking open wounds or irritated skin on each other.
  • Normal brief licking between healthy dogs is rarely a big issue, but if either dog has dental disease, infections, or face sores, limit it and talk to your vet.

Quick TL;DR

Dogs lick each other’s mouths because:

  1. It starts as a puppy “please feed me” reflex.
  2. It becomes adult social language: affection, respect, and calming signals.
  3. It helps them gather info about where the other dog has been and how they’re doing.

As long as both dogs seem comfortable and relaxed, this quirky behavior is just one more way they “talk” to each other. Information gathered from public forums or data available on the internet and portrayed here.