What are some ways to tell if a dog is in pain?

As in the case following surgery, for example. Let's be clear: My dog has not had surgery, but I am exploring a hypothetical situation.

Typically, limping, sitting around, lethargy, crying, licking the wounded area.

Dogs mostly make painful sounds. High pitched, not very nice to listen to sounds.Or they might just not move if its something really painful. But really they just sort of.... yell? They make very painful sounds. I have a dog and if something happens to her, she just yells, sticks her ears back, tucks her tail under her butt and just makes painful sounds. Then when its over (a few seconds) she just starts being herself again and goes happily back to what she was doing. Shes a crazy little dog! :)Hope that helped.

If you hear the dog whining when he or she is walking or running is one way. The dog won't get up if it's laying down. Also if you look at the face you can tell