I get to spend a lot of time observing different groups of dogs because of my work as a dog walker and dog rescue volunteer. One of the behaviors I see quite often is one dog licking another in the face, sometimes obsessively. However, nothing is that simple with dogs and there are all sorts of reasons why they lick one another and us in the face. This is not research-based.
Why Does My Dog Lick Other Dogs in the Face? | feriadelitago.com : A Dog Blog
See if this sounds familiar: After going for a long walk with your dog and feeding her, you sit down to relax. She comes over, so you start petting her, but as soon as you do, the licking begins. This happens every single time you offer affection! Dogs lick their pack members and themselves for many reasons, and if you want to curb the behavior , it helps to understand its cause. Sometimes we have tiny food particles that they can taste, and beyond that, dogs enjoy the salt on our skin. You might not think of your pup as particularly concerned with hygiene, but dogs often lick to clean themselves, just like cats.
Face and lip licking is most often offered by young puppies, but can carry on into adulthood. Face licking does have boundaries in the dog-to-dog world of interaction and socialization. Young puppies are offered a lot of behavior leniencies by their elders. Their wiggly, squirming, jumpy, face licking greetings are often allowed by older dogs. The adult dog stops, stands still and allows the pup to do his thing before moving on.
Have you ever wondered why dogs lick you? Most dogs love to lick people. It's so common that dog owners usually call it "giving kisses" and consider it a sign of affection. Some dogs seem to lick people more than others.