Adding to the choir, I agree, this dog should never have been left unleashed, unsupervised, able to get that close to the baby. Some owners forget how sensitive dog’s sense of smell is. Newborn babies have a marked scent, one that is at times sweet, other times raw from the animal’s perspective.
This may have been the first time this dog has ever smelled or heard or viewed the delicate movements of an infant. Such puppies or young adult dogs don’t always know what is ‘normal’, so they stay on trigger edge. The dog may have been listening to how the baby was breathing and shifting the blankets around, when suddenly, the owner coughs loudly, creating a sharp break, a distracting sensory overload, where the dog doesn’t know what to react to first.
I agree and mentioned the same in my PULLED POST that showed the dog in question.