What killing the dog symbolized

I believe it symbolized the hope of candy to have a better and more fortunate life and Carlson denies that his dreams will come true. When Carlson says "God all mighty that dog stinks. Get him outta here, Candy! I don't know nothing that stinks as bad as an old dog. you gotta get him out." I feel this is like Carlson saying this is not a time for dreamers, we are workers. I also think this applies to Lennie and how George takes the mice from Lennie.