Hiding more than usual
Acting withdrawn or less social
Hissing, growling, or swatting when touched
Avoiding being picked up
Limping or moving stiffly
Difficulty jumping, climbing, or using stairs
Reduced grooming or an unkempt coat
Overgrooming or licking one area repeatedly
Changes in appetite or drinking
Changes in litter box use
Crying, yowling, or unusual vocalizing
Restlessness or inability to get comfortable
Hunched posture
Tense body or guarding a body part
Flattened ears
Dilated pupils
Faster breathing or panting
Decreased activity or sleeping more than usual
Sudden aggression or irritability
Facial tension or squinting
Weight loss or reduced interest in play