Basically using the reverse Centaur (Kentauroi) concept, just make sure they follow the god Hippoi Athanatoi to throw in a bit of trivia for the player. You could look for drawings of Satyrs to model after, but remember that the Satyr had the head of an ass (or mule) so you will have to elongate the muzzle a bit.

For more information see the Bestiary: www.theoi.com/Bestiary.html