Small dogs and dogs without an undercoat are particularly sensitive to cold, especially in the winter months. Because they lack the protective fur that acts as natural insulation in other dogs, they lose body heat more quickly and therefore get cold more easily. This can cause them to feel unwell or even become ill.
These dogs are particularly at risk in cold, damp weather, as wetness makes them even more susceptible to cooling. In such situations, dog sweaters are particularly useful, as they provide an additional layer of warmth that protects the dog from the cold and wet and keeps it comfortably warm.