Veterinary Science Question:

Crying out or vocalizing repetitively when touched or picked up may be an obvious sign of pain although, a very frightened animal might react similarly. More subtle signs may include restlessness, panting when not hot ( in the case of dogs ), trembling, refusal to eat or reluctance to do a common activity. All of these signs must be viewed in the context of any given situation to be identified as induced by pain since anxiety can produce very similar signs.