A thick coat and a strategic layer of fat may not be sufficient to weather the winter. And if in general cold is not an issue for dogs, there are some exceptions. For example, sensitive breeds such as Boxers and Dalmatians (and all miniature breeds) cannot live outdoors. But extreme temperatures may also affect puppies, sick and older dogs. Dogs can suffer hypothermia, i.e. excessively low body temperature, which in extreme cases can cause death. If your dog got cold and looks unresponsive and numb, has a temperature lower than 37C and slow and irregular heartbeat, you need a vet. If the situation is less serious, you can help by warming them slowly, wrapping them in a blanket, but don't put them in front of a direct source of heat (as they could collapse). Give them something warm to dirk, for example, chicken broth.