It is clear that the mood between these two different scenes could not be more different. The horseshoe game involves all the men enjoying themselves, relaxing and having fun together. It is a place where social divisions are brought down and unimportant, as is shown through the inclusion of Crooks in the game, the negro stablehand who normally spends his time by himself, away from the white ranch workers. Note how the horseshoe game is described:
Through the open door came the thuds and occasional clangs of a horseshoe game, and now and then the sound of voices raised in approval or derision.
By contrast, when Carlson takes Candy's dog out to shoot it, there are no such sounds of joviality and easy companionship. The change of mood is signalled by the oppressive silence that descends on the bunkhouse, in spite of the men's best efforts to fill it:
The silence fell on the room again. It came out of the night and invaded the room... He rippled the edge of the deck nervously, and the little snapping noise drew the eyes of all the men in the room, so that he stopped doing it.
The awkwardness that occurs when George makes some noise identifies how different the mood is in this scene, and this is supported by the way that the silence is personified as being some kind of aggressive warrior or thief that "invades" the room and impacts all of them there. This is a big difference from the easy companionship suggested in the horseshoe game.