Spitz was the lead dog in the team when Buck was brought into the mixture. As such, Spitz was the leader and the others were expected to follow where he went. Spitz expected to be given deferrence by the other dogs, as was appropriate to his seniority and experience. He was strong, understood the ways of the humans, refused to be defeated by the worst of the Artic weather conditions, and maintained order among the other dogs without exception.
This was the pride that bore up Spitz and made him thrash the sled-dogs who blundered and shirked in the traces or hid away at the harness-up time in the morning.
Spitz demanded the obediene and the respect of the other dogs, and for the most part they were willing to concede to his strength, endurance, and experience. He was proud of his abilities as a lead sled dog, and he didn't tolerate challengers.