You can only find them in dungeons. You also cannot recover them off pigs you use them on, nor can you control them really, so I honestly would not use any you find and instead stockpile them for when we get real mounts.
Well, maybe use one just for kicks and giggles. Press F5 to go to third person while on the pig, it's comedic gold. --- -gejsiv- :/ It cost four hundred thousand dollars to read this signature for twelve seconds.