According to Francis, "she doesn't breathe fire... except when she sneezes." Therefore, she's not a fire-breathing horse, but a fire-sneezing horse.
Candy Corn is a type of horse whose body looks like candy corn. Other than her body, she is a white horse with yellow hair and orange hooves.
Candy Corn is featured in the episode March of the Pumpkins. She shows up after the Pumpkin King blows a tune on his flute that sounds like the whinney of a horse. The Pumpkin King has her help Wubbzy pull a giant pumpkin to the Autumn Festival, allowing Wubbzy to win the pumpkin contest.