Had a full-size collie defend me from a bear when I was two. Between Queenie and my uncle who came out with an axe, they drove the bear off. Queenie was like that. I recall nothing about it.
Years later a small dog growled at my daughter who was about 1 1/2 at the time. I took her outside and had my .22. We were taking a trip to the dump. A neighbour (I was teaching on a reserve at the time) saw me and said, "My dad would love to have a small dog." I gave her the dog.
I do NOT allow animals second chances when they misbehave near children. AND, other than an ol' German Shepherd I owned--more like she owned me--I would never allow any animal to be alone with a child. Period.