Rufus was a piebald gelding who belonged to Jackie Kennedy. Little is known about Rufus, other than that he appears to have spent his life on the Kennedy property in Atoke, Virginia. Jackie was an accomplished horsewoman for the entirety of her life, and she often enjoyed taking Rufus out on long rides. She even rode Rufus during fox hunts, following the traditional hounds.
Rufus was never reported to be at the White House, which explains why there is so little information about him. It is likely he happily lived his life in Virginia, chasing the hounds whenever Jackie required it.