One of these creatures ran loose in a Fire Nation bazaar visited by Team Avatar. After seeing the animal enjoy a meal of meat, Sokka was inspired to use it as a persuasive argument to coax Aang into entering a meat shop with them, noting that even the meat ate meat.[1]
A flying, fire-breathing hippo cow carrying Fire LordOzai on its back appeared in one of Aang's nightmares.[3]
The hippo cow has a small set of horns and floppy ears, and is mostly white with irregular black spots on its skin. It has the head and body of a hippopotamus but the horns and coloring of a cow, with short, stubby, hippo-like legs that end in cow-like hooves; hippo cows also have udders just as cows do.
The hippo cow has the body shape of the real-life hippopotamus. However, its horns, udders, and colors are that of a Friesian cow. Despite the fact that both of its namesakes are normally herbivorous, the hippo cow eats meat. The hippopotamus is known to scavenge corpses already killed by crocodiles in times of need; the hippo cow is only seen eating the meat of already dead animals, so it is somewhat like the real-life hippo in this regard.