1. Werewolves are violent to the extreme, so if anything, I would see it as a punishment for violence. Force them to attack again and again to the point of self-loathing so that they learn to hate violence and stay away from it. It could have been an accident, but the witch might not know that.

2. I would probably do whatever I could to keep it a secret and possibly find ways to keep him from running amok at night while searching for cures in books and whatnot.

3. Abuse or abandonment