Changes in behavior or temperament

• Aggression 

• Disinterest in people or other pets/reluctance to play

• Unusual vocalization

Lethargy or restlessness

Licking frequently in a given area

Loss of appetite

Difficulty climbing stairs or jumping

Difficulty getting up after lying down

Limping or lameness 

An abnormal gait or posture

Stiffness

Swelling or inflammation