They clean their face; they give us kisses, they scoop water up them, they cool their body and they give us some great entertainment, a dog's tongue. When I have the chance to shoot some dogs having fun; the tongue is most often hanging around. Sometimes people don't want their dog's tongue hanging out for a shot, they prefer a more closed mouth look. I don't care either way but when they are hanging out? It usually means fun is being or has been had.
Sometimes the tongue is used in a controlled manner; when panting is minimal it is usually held out a small bit with the end curled up. But when fun has gone on for a while and all involved are heating up, the tongue seems to take on a wild and unruly persona.
Tongues can be used to clean up small messes.
Or full face messes; as required.
Often they just blow in the breeze; with no rhyme nor reason.
Tongues can signal a warning to those around.
Our dogs use them to drink with.
Whether they are being pulled back, under control, cooling or swinging uncontrollably a dogs tongue is extremely multi-functional.