re: How cold is too cold for smallish dogs?

sister can see the dogs from her house.

Dogs have lived outside for tens of thousands of years before we started domesticating them. They’ll be just fine in a southern winter. I might think twice if I lived up in NY or something, but down here where the absolute worst they’ll probably see is around freezing, maybe mid 20s once every 5 years, outside in a dog house with some blankets/hay/heat lamp is perfectly fine.

Tell your sister not to worry about it. We have a 14 year old terrier mutt for one of the family dogs. She’s 20 pounds with short fur and hasn’t slept inside a day of her life and she’s more than fine.