What happens to the dog's remains in "There Will Come Soft Rains?"
In "There Will Come Soft Rains," the dog survives the nuclear blast but later dies of radiation sickness. Its body lies in the parlor for an hour and, by two o'clock, the "regiments" of mechanical mice have realized that it has died. It takes the mice fifteen minutes to clean up the dog's remains, bringing the time to two-fifteen in the afternoon.
As the previous educator has noted, it is likely that the mice dispose of the dog's remains in the incinerator because it is mentioned in the text directly after the disappearance of the body:
"The dog was gone.
In the cellar, the incinerator glowed suddenly and a whirl of sparks leaped up the chimney."
Once the dog's remains have gone, all traces of the previous occupants are removed. Every member of the family is now deceased and the house becomes the sole survivor. Even an accidental fire cannot completely destroy it: the story closes with one remaining wall, standing alone among the rubble.
After the dog died, it lay for an hour in the parlor until the mechanical cleaning mice "sensed" the dog's decaying body. Within fifteen minutes, the mice had done their work, and the dog's body was gone. The following passage implies what had become of the dog's remains:
In the cellar, the incinerator glowed suddenly and a whirl of sparks leaped up the chimney.
We can infer that the cleaning mice took the dog's body to the basement, placed it in the incinerator located there, and burned it up.