Provide insulated housing that is small enough for the body heat to keep the pet warm. To put your pet in an unheated garage is not adequate. There must also be a small house present even in a garage, the pets body heat cannot heat a whole garage. If the insulated dog house is outside, the entry to it must not be facing where direct cold wind can enter. Face it away from the wind direction.
Cats often get frost bite on the tips of the ears.
Resulting in the tips of the ears falling off. Dogs with thin ear tips may also become frost bitten. Pets generate body heat from calories produced by food. Fat is the the ingredient that produces the most heat. Dogs only have sweat glands in their foot pads.