The Call of the Wild
How we cite our quotes:
They were all terribly footsore. No spring or rebound was left in them. Their feet fell heavily on the trail, jarring their bodies and doubling the fatigue of a day's travel. There was nothing the matter with them except that they were dead tired. It was not the dead-tiredness that comes through brief and excessive effort, from which recovery is a matter of hours; but it was the dead-tiredness that comes through the slow and prolonged strength drainage of months of toil. There was no power of recuperation left, no reserve strength to call upon. It had been all used, the last least bit of it. Every muscle, every fibre, every cell, was tired, dead tired. (5.2)
Buck’s fatigue becomes not just a physical suffering, but emotional and mental as well. He and the other dogs are unable to travel as they are "tired" in many senses of the word.
The Outside dogs, whose digestions had not been trained by chronic famine to make the most of little, had voracious appetites. And when, in addition to this, the worn-out huskies pulled weakly, Hal decided that the orthodox ration was too small. He doubled it. And to cap it all, when Mercedes, with tears in her pretty eyes and a quaver in her throat, could not cajole him into giving the dogs still more, she stole from the fish-sacks and fed them slyly. But it was not food that Buck and the huskies needed, but rest. And though they were making poor time, the heavy load they dragged sapped their strength severely. (5.37)
The experience with Hal, Charles, and Mercedes is arguably the most harrowing part of Buck’s journey. The men’s ignorance of dogs and travel is irresponsible.
A poor substitute for food was this hide, just as it had been stripped from the starved horses of the cattlemen six months back. In its frozen state it was more like strips of galvanized iron, and when a dog wrestled it into his stomach it thawed into thin and innutritious leathery strings and into a mass of short hair, irritating and indigestible. (5.46)
The dogs’ hunger goes unsatisfied when under the command of Hal and Charles.