"Warning signs" are indications or signals that something is wrong, dangerous, or may cause harm. They serve as alerts or cues to be cautious, pay attention, and take necessary actions to avoid potential problems or harm. Full definition
Also make sure you have a look at this list of warning signs of cat illness. (cat-lovers-only.com)
Know the breed tendencies and observe your dog's behavior for early warning signs of this risk. (vin.com)
A checklist of warning signs for the top causes of death or medical complications postpartum, with instructions that if you have any, you should call your doctor. (romper.com)