The Giant Schnauzer is a working breed of dog developed in the 17th century in Germany. The Giant Schnauzer is a working breed of dog developed in the 17th century in Germany. It is the largest of the three breeds of Schnauzer—the other two breeds being the Standard Schnauzer and the Miniature Schnauzer. It was unknown outside of Bavaria until it became popular as a military dog during World War I and World War II. Giant Schnauzers have been described as trustworthy with children. They are very intelligent, and can become bored easily. They are very intelligent, and can become bored easily. They are also very energetic and highly spirited, which, when coupled with boredom, can lead to unwanted and destructive behavior.