I had a similar experience except it was in daylight. Huge dog broke open a storm door and charged me and my dog (Tangle). I began moving me and Tangle as far across the road as I could get.
In that mental state that seems like "instantaneous assessment", I decided to draw if the dog came into the road, and the instant I perceived he was a threat, the shooting would begin. The dog charged into the street, I had already drawn my gun - nerves gave in early. Just as it was time, I heard the owner (a woman) yelling he won't bite. I trusted her; thank goodness she was right.
She new I had a gun - out. I got back to my mother-in-laws ASAP and called the police and told them the story. I didn't want the owner calling in and reporting some guy pulled a gun on them.
I'm sure glad I had night sights on my gun when that happened, otherwise this post would be drifting off topic.