Chad Clark's Open Journal : 2010-05-20

1) Mice show pain through facial expressions.

The Globe and Mail reports mice "squeeze their eyes, scrunch up their noses
and push out their cheeks, much like humans do".

  They also push back their ears and move their whiskers, says Mogil, who
  collaborated with the University of British Columbia’s Kenneth Craig on
  the project. When these features are combined in one expression, it means
  the mouse is hurting