Hippo/Hippopotamus. =]
yes, a hippopotamus is sometimes referred to as a river horse.
Obis Horse
horse soldiers
a stalion.
If you ever see the word horse after another word, that is usually the breed. Pampas horse is probably a breed, horse is just a general word, the breed is more specific.
Another word for mare would be filly
Charger is one such word. Champion is another one often associated with a horse.
longshot, dark horse
Rider Up!
Flying donkey
If you mean another word for "Quarter Horse", there aren't any others. A Quarter Horse is a breed of horse.
black and white mini horse