Severe weakness or inability to stand
Loss of appetite for more than a day or two
Difficulty breathing or very slow, labored breathing
Unresponsiveness or extreme lethargy
Collapse or repeated fainting
Pale, blue, or gray gums
Loss of bladder or bowel control
Persistent vomiting or diarrhea
Seizures or uncontrolled shaking
Very cold body temperature
Refusal to drink water
Signs of severe pain that do not improve
Confusion, disorientation, or inability to recognize surroundings
Rapid decline in mobility or coordination
Withdrawal from people, pets, or surroundings
No interest in favorite activities or treats
Abnormal heart rate or very weak pulse
Continuous crying, whimpering, or signs of distress
Swollen abdomen or obvious bloating
Inability to get comfortable or rest
Sudden severe changes in behavior or alertness