[Getready]

How is it accidental if dog overpowered handler to get at the kid..?
I love animals but they have bounds....human involuntary or involuntary negligent homicide to me. When people start getting dinged for the acts of their pet killing somebody, ownership will change

[Politically Correct]

From the story (notoriously unreliable reportage) the grandmother (not the owner) was moving the dog (why is not stated) from the room that the owner had locked the dog in.
Dog breaks free and kills child.

The only one negligent is the grandmother (not the dog's owner) in her estimation of being able to control the dog (she was wrong).

I'm not sure that I'd be interested in claiming negligent homicide and exposing the grandmother to legal peril.