What did Manuel do to buck in call of the wild?

In "The Call of the Wild," Manuel, a stable hand, betrays Buck by selling him to dog traders after he has been living a comfortable life as a household pet. He lures Buck with the promise of a walk, only to kidnap him and transport him to the harsh wilderness of the Yukon. This act sets off Buck's transformation from a domesticated pet into a wild creature, ultimately leading him to embrace his primal instincts.