"Too true, sir," said the mare with a melancholy whinny.
Just as Shasta was saying to himself, "We must be nearly at those sandhills by now," his heart leaped into his mouth because an appalling noise had suddenly risen up out of the darkness ahead; a long snarling roar, melancholy and utterly savage.
There are no more uses of "melancholy" in the book.
Show samples from other sources
Since her dog died she’s been in a melancholy mood.
This weather makes me melancholy. I can’t wait for spring,