A good rule of thumb is that a dog run should be twice as wide and at least four or five times as long as your dog is long. (Measure your dog from the tip of the nose to the base of the tail.) A long rectangular shape rather than a square shape provides a better exercise area. If space is limited, do not skimp on the length of the run. The location of the run is also important. If you cannot locate the run where it will receive shade all day long, put it in a spot that will be well shaded in the afternoon. If your yard has no trees or if shade is unavailable during the warmest part of the day, you will need to build some kind of solid panel to provide shade over at least part of the run to at the same time you build the run. An option is to stretch a plastic shade cover over the top of part of the run. In heavy snowfall areas, the cover must be removed and stored during the winter.