Tosa Ken

The Tosa survived the ravages of World War II only because individuals had been exported previously to Taiwan and Korea. It descends from smaller Japanese fighting mastiffs that were selectively bred up in size through crosses with larger European breeds, such as the Great Dane. Today, it is very rare in Japan and even in the United States, and is banned in some countries due to its background. Males are dramatically larger than females, sometimes almost double their weight. Owing to their fighting ancestry, this breed can be formidably aggressive with other dogs unless socialized well when young.