To protect themselves from predators, animals naturally hide their pain. Your pet may be suffering even though he isn’t showing obvious signs. Advancements in veterinary science have decoded subtle telltale signs of animal distress. Observing your pet’s behavior is vital to managing his or her pain. How well do you know your pet? Use these five clues from the 
American Animal Hospital Association (AAHA) to help you understand your pet’s body language.
American Animal Hospital Association (AAHA) to help you understand your pet’s body language. Clue 1—Abnormal chewing habits
If your pet is showing abnormal chewing habits, such as dropping its food or chewing on one side of the mouth, it may have a dental disorder or a mouth tumor. Additional signs may include weight loss, bad breath or excessive face rubbing. Routine dental checkups are important to prevent and treat dental disorders and related pain.
Clue 2—Drastic weight gain or loss
Continued here: http://healthypet.com/library_view.aspx?ID=200&sid=1
