Winter jumpers and coats for dogs have become ever more popular in recent years - but are they just fashion accessories, or actually necessary to keep your puppy warm?

Dogs are naturally protected against cold temperatures, as most breeds have a warm layer of fur or hair to keep themselves toasty. According to veterinarian Micheline Boone, however, in some cases clothing can be of use: "Breeds with short hairs and no undercoat, like Yorkshires, Chihuahuas or Jack Russels, as well as other bigger dogs such as Mastiffs or Dobermans, can indeed be given an extra layer."

Boone explains that winter clothing is especially fit for puppies, which have not yet developed thicker coats to keep out the cold. Older or sick dogs may also benefit from additional help.

Dog owners should be careful with their choice of clothing for dogs, however. While designer outfits might look pretty (in the eyes of some, at least) they are not always useful, as they may limit your dog's movement. Some materials may also be irritating for your dog; Boone recommends polyester or nylon.

As a general rule, your dog will let you know if it's too cold, by either shivering or refusing to walk after doing its business. Keep in mind that younger or older dogs might also need shorter walks depending on weather conditions.