Sad story. From the looks of it, it could be neglect on the part of the parents, or it could be a terrible series of misfortunes leading to an unpredictable disaster.
It seems the dog was locked in a bathroom, but the 3-year-old let it out in the night. The parents were not awakened (drugs - legal? or illegal?) and the baby was not in a crib. I would not call a baby sleeping somewhere other than a crib child abuse. I know my children fell asleep in places other than cribs a lot.