After being bested by the MC, he somehow gets angry and starts to kill the MC for real then gets stabbed in the eye. Mad dog is ANGRY at the MC because he lost and got stabbed in the eye when he was the one who initiated the fight in the first place.
To sum this up... Its like Mad Dog is saying: "How dare you betray me after I ruined your life turned you into a child soldier and forced you to kill" Im glad, the author decided to stop dragging this after 5 chapters.
Mad dog is ANGRY at the MC because he lost and got stabbed in the eye when he was the one who initiated the fight in the first place.