How is the incident with the dog symbolic of Candy's life on the ranch?

Chapter 3

The dog, like Candy, is old and wothless. Carlson says the dog stinks and "ain't no good" for itself anymore. Candy feels like this too. He is kept on to sweep and clean but he sees the writing on the wall so to spreak, "I wish't somebody'd shoot me if I got old an' a cripple..."

Almost every word in the book "Of Mice and Men" is chosen for a specific reason. i.e. it may be a metaphor for something or may signal an forthcoming event. Similarly Candy's dog is a very carefully crafted character. It symbolizes two things. The fist being Lennie's death in the end of the book and secondly the life or status of Candy. The dog is symbolic for anything that has outlived its usefullness. It is described as "useless"; "stinking". It also shows the lack of respect for peoples feelings and sentiments as it was candy only so called "companion" but shot in cold blood.Candy just like the dog is approaching the last phases of his life. Now that the dog is of no use to anyone but Candy, he is ignored and branded as "useless". However we are told that once younger it was a good "sheepdog". This is however not taken into consideration nor the fact that it means so much for Candy. Similarly Candy too is like the dog, old, crippled, lonely. The similiarities show that once Candy too is unable to work, will be deemed usless and be disposed off.