It's a dog, not a wolf. It literally said so in the page.
He's strong enough to kill it with his bare hands, seemingly without any issues considering he was immediately talked to by someone who wanted to make him an apprentice. He's strong enough to not kill it and get away. The kill was intentional. Not saying dumb things like an animal's life is more important than a person, but it's not a kill or be killed situation, or at least it wasn't presented that way. Needless killing of any kind makes him a POS.