how is candy's dog and what happens to it a metaphor for how candy feels about his own life?

Candy's dog is the love of his life; they kill him because he's old and he stinks..... because he's not good for anything anymore. This is the dame way Candy sees himself...... old and not good for anything.

Candy feels old and worthless like his dog. Candy says that he hopes somebody will do the same to him when the time comes.