He only appeared in the cartoon A Knight to Remember of The New Adventures of Winnie the Pooh. We only see the silhouttte of a giant Eeyore, but when Piglet the knight shrinks him, he looks like a normal Eeyore.
He was turned into a dragon a week from Piglet's visit. When Piglet found him, his armor broke and his magic sheild given to him by Gopher's paralell counterpart is shattered by Eeyore's roar. He then uses Magician Rabbit's third spell to shrink Eeyore to normal. To repay Piglet, Eeyore was made the Knight to Remember by King Pooh and he then sees Piglet return home