The story
Coined and conceived in 2009 by costume and fursuit designer Deanna "Ino" Biesemeyer, from Dutch (“a male given name”) + angel + dragon. So-called because the fictional characters are guardian angels and ostensibly resemble dragons, and named after (and inspired by) her late palomino gelding horse, Dutch, who died in 2006.
Etymology from Wiktionary, CC BY-SA 4.0.