The next few pages, in which the others urge Candy to shoot his old dog, are heavy with symbolism. This is one of the most important scenes in the book.
It demonstrates the harsh attitude of life on the ranches: when something is no longer useful it is simply discarded. This is the life that George and Lennie have to deal with, and it explains why George is so anxious to become a land-owner, to take control of his own destiny and ensure that he and Lennie are never discarded for being useless. Old age is not friendly to ranch-hands, and everyone is anxious to continue proving their worth, or to find some kind of security for their old age. This also explains why the men all act so suspiciously and closed-off around each other. No-one feels as though they can truly trust anyone else; everyone has to look out for themselves in this harsh world.
It is also one of the more moving examples of animal imagery in the book. Many animals are shown being killed before they are able to die a natural death. This shows how life can bring unexpected, cruel turns, which connects to the book’s title. 'Of Mice and Men' comes from a Robert Burns poem (‘To a Mouse’):
“the best laid schemes of mice and men often go awry”
Time and again, lives are overturned by forces beyond their control.
The death of the dog emphasises themes of loneliness within the story. Candy allowed himself to love the dog too much, and it was taken away from him. Now he has no companion.
Finally, this scene strongly foreshadows events to come.