My mother sent me the annual sheet of horse stamps as a Christmas present. It never arrived. Fortunately, while visiting the main post office in Tokyo, I managed to find a set and here it is! As you can see, there are many ways to write "horse." The more traditional kanji style is the stamp on the middle right. A katakana version is on the bottom left. Other versions include "grass style" flowing calligraphy, pictogram and even a seal.