It is normal for dogs to pant heavily during and after exertion. But panting after exercise can sometimes also indicate medical emergencies, including pain, heatstroke, or poisoning. It’s also one of the dog illness symptoms to watch out for. “Panting is a subtle, often overlooked sign of pain. Some dogs in pain pant more than usual, but eat, drink, and seem normal. If the temperature where the dog spends most of their time hasn’t changed much, but the amount they’re panting has, heed this warning and consult your veterinarian right away. Panting can also be a subtle sign of severe pancreatitis. It was in my own dog, and even I, as a vet, missed it for a week,” shares Dr Robinson. In the worst case, these symptoms can mean that your dog has cancer.