The Question and Answer section for Call of the Wild is a great resource to ask questions, find answers, and discuss the novel.
The Scotch half-breed treats the sled dogs fairly though he is equally hard on them. We never find out the name of the Scotch half-breed perhaps because he simply represents unnamed authority without excess of good or bad traits. There is no...
I think that was the Chilkoot Trail.
This is explained in the anaysis section for chapter 4 at the GradeSaver link below: