In the first place, it’s stupid to sleep with a child small enough to smother. Toss in a dog which might have fleas, tapeworms, hookworms, mange, etc., the stupidity level increases exponentially as to what could go terribly, terribly wrong.
It’s curious that the puppy chose the baby to chew on, and that it’s presumed cries of pain went unheard or unvocalized. Something seems off.
This is a tiny too-young 6-week puppy.
I have a feeling, the puppy was there and found a plaything and kept gnawing at it, even as it would move a bit and cause extra interest. The baby’s mouth could even have emitted smells such as milkiness that would be interesting to a dog of any type but esp. a puppy.
I sort of doubt this was all about “viciousness”. The puppy is too young to leave its dam and may especially try to keep feeding on a soft rounded milky moving thing it found.
I despise pit-bull terriers, but I sort of doubt that was the real cause here.
Highly negligent parents - gee, I wonder why?