Mice have a crucial importance in the novel, as well as Lennie's relationship with the mice. Firstly, Lennie likes to feel soft things, and his obsession with with petting mice grants him with security and comfort. Even if the animal is lifeless, Lennie still pets it to comfort it as well as to comfort himself. The simple feeling of the mouse's smooth fur running between his fingers provide him with a sense of contentment. This symbolizes his soft and caring attitude along with his warm heart. Secondly, the dead mouse in Lennie's pocket is a strong symbol foreshadowing the end awaiting all weak and helpless creatures. This shows that not only is Lennie symbolically playing with death, but that, in his perspective, death isn't a fear of his.
The reader learns that the dead mouse Lennie finds is not the first mouse he has had, but because of his strength, they always ended up dead if they were alive to begin with. Therefore, the mouse Lennie finds dies a fast untimely death. Thirdly, even with Lennie's physical strength and size, his childlike mental capabilities make him as helpless as a mouse. The fact that Lennie gets, and accidentally kills the mice he has, reveals his uncontrolled strength and his compassion for soft things.
Rabbits are also another notable animal mentioned in the novel. Firstly, they are the only thing that Lennie does not seem to forget. Every time he asks George to tell him the story of their little house, he always mentions the rabbits, as if without the rabbits on their land, even if they would have a place they can call their own, it would not be the same. Secondly, the rabbits that Lennie hopes to have and care for give George control over him. Lennie's happiness is based on his hopes for this land, so he will be able to tend his rabbits.
Knowing this, George constantly threatens him with not allowing him to tend the rabbits if he does not behave and follow his orders. George tells Lennie '' if you do [get in trouble], I won't let you tend to the rabbits,'' (p.17). This becomes Lennie's motivation to behave and to watch what he does. He imagines stroking an looking after his rabbits on the little house he and George plan on owning. For this reason, being he has something to hope for, he tries harder to be good and has no limits of what he would do for his dream to come true. And Finally, like mice, rabbits are soft creatures that Lennie does not only wish to tend but to pet as well.
Dogs are principal animal figures stated in the novel. Firstly, Steinbeck starts by comparing Lennie's loyalty to that of a dog. '' His huge companion dropped his blankets and flung himself down and drank from the surface of the green pool, '' (p.4). Although he does not do so directly, this image compares Lennie, when he is drinking from the pool, to, as the phrase goes, ''man's best friend''. Throughout the book, Lennie proves his complete loyalty and unconditional love and friendship. Like a dog, he does not understand certain concepts. He also does not think about the consequences of his actions. Steinbeck's comparisons between Lennie and animals, like dogs, bears, and horses, reinforce the impending sense of doom.
Secondly, Candy's dog has a great importance in the novel as well. His death is linked to the death of Lennie because this dog represents the fate awaiting anyone that becomes no longer useful. In other words, anyone who outlives his or her purpose will be put out, one way or another. The dog's death brings out a major fear in Candy. He himself is nearing an age when he will no longer be useful on the ranch and therefore will no longer be welcomed there either. Finally, Lennie's puppy is one of several symbols that demonstrate the victory of the strong over the weak. Lennie kills the puppy unintentionally, as he has killed many mice before, for the plain reason that he does not recognize his own strength.
Animals in the novel, from mice to rabbits to dogs, all die untimely deaths and have an intense significance. Steinbeck's references to animals portrays the characteristics of the characters as well. These comparisons are not only meaningful in the book but also in real life.