Is the doggie sweater (jacket, snowsuit, raincoat, etc.) really necessary? The answer boils down to what your dog is naturally equipped with, coat-wise. Double-coated dogs with high coat density like Akitas, Malamutes, and Siberian Huskies were bred for harsh conditions and are uncomfortable with outerwear of any kind. Double-coated dogs with lower coat density like Collies and Shepherds are fine in most bad weather. They need clothes and boots only if exposed to extreme cold.
However, single-coated dogs like Yorkshire Terriers and Papillons must be dressed well for any rough weather. Ditto dogs with a hair coat, such as Poodles and Maltese. And regardless of breed, older dogs and dogs with weak immune systems may benefit from the extra warmth clothes provide. If in doubt, check with your veterinarian or simply watch your dog. If she shivers, she’s too cold.