Why does candy say that he should've shot his own dog?

Candy expresses regret about not having shot his own dog himself because he feels a sense of responsibility for its suffering and recognizes that it would have been a more dignified end. The dog's death symbolizes the harsh realities of life on the ranch and the inevitability of aging and uselessness. By suggesting he should have done it himself, Candy also highlights his feelings of powerlessness and the loss of control over his own life and future. This moment reflects the broader themes of loneliness and the struggle for agency in a brutal environment.