of mice and men

I don't think these ranch guys view animals in the same way that urban populations might. These guys work hard and animals, even domesticated dogs, are a tool to get work done. When animals cease to be of service, they are usually put down. Candy's dog stayed with him in the bunkhouse. He was old and smelled bad. Carlson wanted to do what should have happened, on a ranch, a long time ago. Carlson was able to silently get Slim's okay to shoot the dog. This was enough to get Candy to concede.