The tired dog is sacked out on the rug.
sacked out
idiomSound asleep, usually from a healthy exhaustion.
Origin
disputed originOutgrowth of the earlier idiom, to hit the sack (“to lie down to sleep”), with possible influences from other senses of to sack (“to tackle, to pillage”), and to sock (“to hit, to slam”), providing an implication that sleep has been thrust upon a person.
After hiking all day, the campers were sacked out in their tents before the sun even set.
Exhausted by the grueling demands of the marathon, the athletes remained sacked out in the locker room long after the race had concluded.