I have a mini pin and they only have one layer of fur which makes it difficult for them to retain their body heat especially during the colder months. He is always under blankets trying to keep warm. Last winter it was so cold in Indiana that we made him put on a sweater and make him a fleece coat to go on top of it and make him fleece boots with denim on the bottom to help protect his feet. It was so cold that he got bundled up to go outside to pee for a minute and then come back in. If he didn't have all of that then he would not have been able to go outside at all. I think it is important to think of dogs as more than just pets or animals. Some of them are not able to tolerate the cold as well as others. They have the same biological functions as humans and are just a susceptible to hypothermia. I definitely think that if your dog can't handle the cold then they should have a sweater or coat to help them out.