How does Buck respond to the first fight to the death that he watches?

In chapter 2, Buck witnesses his first ferocious dogfight when a massive husky suddenly strikes Curly, tearing the flesh from her eye to jaw. Curly attempts to defend herself by striking back at the husky, and Buck watches as thirty to forty huskies rush to surround the two fighting dogs. After a series of exchanges, Curly runs towards her enemy and loses her balance. The second Curly falls to the ground, the surrounding huskies pounce on her, brutally tearing her to shreds and ending her life. Buck is both astonished and appalled by the savage nature of the dogs. He is taken back by the brutality of the animals and learns two valuable lessons. Buck learns never to lose his footing during a fight and that there is no such thing as "fair play" in the wilderness. The horrific, violent scene of Curly's death haunts Buck's dreams, and he develops a deep hatred toward the lead dog, Spitz, who seemed to enjoy Curly's pain.

Buck has two clear responses to the first fight to the death that he witnesses. They are both foreshadowed in the title of chapter 2, which is “The Law of Club and Fang.” Buck gets a quick introduction to this law when the dog he traveled with, Curly, makes advances towards an unknown husky.
Without warning, the dog leaps upon her and begins a fight that Curly cannot avoid. The two dogs are quickly surrounded by a pack of onlookers that seem to be waiting for something that Buck doesn’t comprehend. When Curly falls to the ground, the husky pack finishes her off.
Buck immediately understands that this is the way of the land he has come to, in that there is “No fair play.” His first response is one of self-preservation; he says to himself that he will stay on his feet in whatever fights he gets into. His second response involves another dog who seems to revel in the death of Curly. Buck’s sense of justice is keen, and although he will abide by the law of club and fang, he does not rejoice in the death of innocent things. This value conflict sets up a rivalry between Buck and the other dog, Spitz, that will continue for several more chapters.