Buck was humiliated right away in chapter 1 of the book The Call of the Wild.
Buck has a pretty good life at the estate of Judge Miller. He is well taken care of, fed, and groomed. He has the entire property to range with no fear of predators or mistreatment from his master. Unfortunately, Buck does not realize that all humans are not as altruistic and nice to dogs.
Manuel "dognaps" Buck in order to pay off some gambling debts. Buck is tied up, placed in a crate, and shipped off. Buck has learned very quickly how naive he was about men, and he is humiliated and angered by his newfound knowledge.
There he lay for the remainder of the weary night, nursing his wrath and wounded pride.
Buck is again humiliated by his inability to beat and escape from the man in the red sweater; however, the encounter with that man teaches Buck some valuable lessons about power.