I got one of these for my short coated boxer/pit mix. She loves to play in the snow, but will barely go out to pee when she is cold. We go to the dog park everyday and usually are there at least an hour. In the winter she turns into a pupsicle after about 10 minutes, leaving us with a dog bursting with energy when we want to sleep. With this coat, we can make it an hour or more and get a tired pup. It needs to fit snug, think like a speedo. I would size down, our girl is 42 pounds of muscle and in a medium. Better yet, take your dog to the store to try the coat on, we had to exchange our large even though we went by the measurements.