Dave (a dog) Timeline and Summary

Dave is another dog that François and Perrault take to Alaska.
He becomes an asset to the team, pulling behind Buck, closest to the sled.
He becomes a teacher to Buck.
Something goes wrong with Dave, but it is not anything physical the men can find.
Dave gets sicker and sicker, but refuses to leave his spot in the traces.
He insists on dying while pulling the sled, too proud to let any other dog do his share.
Dave dies by a bullet, in order to end his suffering.