1. Severe bleeding or bleeding that doesn't stop within 5 minutes.
2. Choking, difficulty breathing or nonstop coughing and gagging.
3. Bleeding from nose, mouth, rectum, coughing up blood, or blood in urine.
4. Inability to urinate or pass feces (stool), or obvious pain associated with urinating or passing stool.
5. Injuries to your pet's eye(s)
6. You suspect or know your pet has eaten something poisonous (such as antifreeze, xylitol, chocolate, rodent poison, etc.).
7. Seizures and/or staggering.
8. Fractured bones, severe lameness or inability to move leg(s).
9. Obvious signs of pain or extreme anxiety.
10. Heat stress or heatstroke.
11. Severe vomiting or diarrhea - more than 2 episodes in a 24-hour period, or either of these combined with obvious illness or any of the other problems listed here.
12. Refusal to drink for 24 hours or more.
The bottom line is that ANY concern about your pet's health warrants, at minimum, a call to your veterinarian.