What does it mean when a dog licks?

There are a few reasons why a dog licks.

A dog's saliva contains a healing agent and dogs often lick another's wounds in an attempt to heel them.

Dogs will also lick as a way to show submission. A submissive dog will hold himself very low, slinking himself down to try to appear smaller. He will approach a human with his head lowered and his ears slightly back as if to say “you're my boss.”

Some dogs will lick another in a dominant manner. For example, mother dogs lick and groom their puppies and for the pups it is the mother displaying leadership. Mom says stay here and be groomed because she is alpha over them and she says so. Submissive licking and dominant licking have different body languages. A dominant dog will carry himself high and proud. He approaches things with an air of confidence. He may also be very persistent as to what he wants.

Sometimes dogs lick out of obsession. Dogs that lick others in an obsessive or dominant manner need to be corrected and the dog must be told not to lick.