Not all dogs need jackets, as there are many factors that determine whether an individual dog requires outerwear for warmth or protection. A dog's size, breed, coat length and thickness, and climate are key considerations. Small dogs and dogs with very short or thin coats may appreciate a jacket in cold or wet weather. Dogs that have difficulty regulating their body temperature, like greyhounds and chihuahuas, are also more prone to feeling chilly. However, large breed dogs and those with thick, insulating undercoats like huskies, malamutes, and many shepherds, are well equipped to handle cold weather without a jacket in most climates. The length and quality of a dog's coat provides natural insulation against the elements. A dog that spends most of its time indoors may not require outerwear either. Overall, jackets can provide added warmth and protection from rain or snow for dogs that need it, but not all dogs require jackets for regular outdoor activities. Understanding your individual dog's needs is important for determining whether a jacket is recommended or not.