Hiding more than usual
Sleeping much more or less than normal
Loss of interest in playing
Reduced appetite or eating less
Changes in grooming, such as neglecting coat care
Increased clinginess or withdrawal
Less interaction with people or other pets
Changes in litter box habits
Excessive vocalizing or unusual silence
Irritability or aggression
Restlessness or pacing
Weight loss or weight gain
Signs of stress after a major change in the home
Not responding to favorite toys, treats, or routines
Lethargy or low energy for several days
Frequent hiding in unusual places