But did the dog die as a result of being in the overhead locker?
Snub nosed breeds of dog are more likely to die when in aircraft (in the hold or cabin), than normal breeds of dog. They're bred to effectively have a slight breathing difficulty.......which turns in to suffocation as the cabin pressure climbs.
So this dog would have most likely died regardless of whether it sat in the overhead locker or on the captains knee munching on the remnants of the flight deck cheeseboard.