Changes in appetite or drinking habits
Sudden weight loss or weight gain
Vomiting or diarrhea
Lethargy or unusual hiding
Trouble breathing or coughing
Sneezing, nasal discharge, or eye discharge
Changes in litter box habits
Straining to urinate or defecate
Excessive grooming or lack of grooming
Bad breath or drooling
Limping or difficulty jumping
Swollen, painful, or bloated abdomen
Pale, yellow, or blue gums
Fever or unusually warm ears and body
Seizures, collapse, or loss of balance
Behavior changes such as aggression or confusion
Scratching, hair loss, or skin irritation
Signs of pain when touched
Dehydration or dry gums
Persistent vomiting, diarrhea, or refusal to eat
Any symptom that lasts more than a day or worsens quickly