Hello Kitty is a cat because Snoopy had already taken the dogs.
Before Sanrio drew her in 1974, its founder, Shintaro Tsuji, showed animal pictures to his son’s classmates. They liked dogs best, but Sanrio sold Snoopy goods in Japan and the dog market was his. Cats came second, so a cartoonist drew a white cat.
Hello Kitty on Brandseum