spent vs dog-tired

spent and dog-tired both are adjectives.

Word	Noun	Adjective	Verb	Adverb
spent	No	Yes	No	No
dog-tired	No	Yes	No	No

As adjectives, spent and dog-tired are synonyms defined as:

spent and dog-tired: drained of energy or effectiveness; extremely tired; completely exhausted

Other synonyms of spent include exhausted, fagged, fatigued, gone, played out, washed-out, worn-out, worn out.

spent (adjective)	dog-tired (adjective)
depleted of energy, force, or strength	drained of energy or effectiveness; extremely tired; completely exhausted
drained of energy or effectiveness; extremely tired; completely exhausted