I told my mum that I got ready to take a swing at it and, if I did hit its nose and put it off, I would have tried to kick it in the head to death if it looked like it was still going to try and bite my arm off.
She was shocked. I think I'm in the right. If the guy can't control his dog and it threatened me and still tried to go for me had I successfully struck it (unlikely), I think I'm entitled to defend myself by knocking it out or killing it. It would be killed later anyway if it did attack me.
Would you defend yourself to that degree against an attacking dog?