Some dogs are more sensitive to the cold than others. Small breeds, short-haired dogs, puppies, senior dogs, dogs classified as “indoor” pets, and those with heart or other medical conditions are all more sensitive to colder temperatures.
When the temperature dips below the normal range, hypothermia happens. Hypothermia means that your dog is losing body heat faster than it can gain heat. Take a look at the article below to see how you can keep your pet warm during the Winter!
https://www.petmd.com/dog/emergency/common-emergencies/e_dg_hypothermia