Hypothermia occurs when a dog's body temperature is abnormally low. Shivering is usually the first sign. The condition also makes dogs tired, and they may look uncomfortable, perhaps huddled up next to the door and wanting to come inside. If your dog is showing signs of hypothermia, bring them inside immediately and wrap them in towels that are warm from the dryer.
Dogs may also hold up one paw or another if they're experiencing discomfort from frostbite — frostbitten skin is red and painful, and it commonly occurs on the webbing in between the toes and the tips of the ears. If you suspect your dog has frostbite, apply a warm, wet compress to the affected area and call your veterinarian for advice. Pat your dog's skin dry instead of rubbing it. Also, don't use heat on any areas you suspect have frostbite.