Dogs suffering from heat stroke will become restless and uncomfortable as their body temperature rises. They will pant, have trouble breathing and feel weak and lethargic. They may whimper, cry out or bark as their discomfort increases. Eventually, affected animals will be in so much distress that they will lie down, become listless and slip into a coma. Unfortunately, by this point, death is fairly imminent unless the dog receives immediate and aggressive medical attention.