Here's why:
* Length: They are longer than they are tall.
* Muscular Build: They have a strong, muscular build that gives them a rectangular appearance.
* Proportions: Their legs are relatively short compared to their body length, further emphasizing the rectangular shape.
While they are generally rectangular, it's important to remember that there can be some variation in individual dogs. However, the overall shape of a German Shepherd is distinctly rectangular.