When a character howls in a raw, somewhat primal fashion to express their grief and anguish. Obviously, it's done most often by canines, but not limited to them.
Can overlap with Clifftop Caterwauling, when this is done at the edge of a cliff. Similar to Big "NO!" and Death Wail.
See also Wolves Always Howl At The Moon and Howling To The Night, for other howling tropes. [tvtropes.org]