Why are the rabbits significant to Lennie in Of Mice and Men?

This answer is interpretive and contains a speculative analysis about Lennie and his motivations.

Lennie does not kill little animals accidentally. He tells George that he usually kills them because they struggle to get away and sometimes bite him. Lennie is looking forward to tending rabbits for two reasons. One is that he will have the pleasure of petting soft little animals. The other reason is that, since he is the one who tends the rabbits, he will be the one who kills them when they are fat enough to eat. In other words, he gets pleasure from petting little animals, and he also gets pleasure from killing them. This pleasure he derives from petting and killing animals is symptomatic of a violence which Lennie does not understand and which George does not suspect until he sees the dead body of Curley's young wife in the barn. George

...was down on his knees beside her. He put his hand over her heart. And finally, when he stood up, slowly and stiffly, his face was as hard and tight as wood, and his eyes were hard.

George is beginning to feel guilty of the girl's death because he brought Lennie to this ranch, because he protected him from the mob in Weed, and because he "should have knew" that Lennie was becoming dangerous. Lennie can't be blamed for being what he is, but that doesn't change what he has become.

"I should of knew," George said hopelessly. "I guess maybe way back in my head I did."

That is the most significant passage in the book. George "should have knew" that Lennie's violence couldn't be controlled. Perhaps Lennie was not interested in feeling the girl's soft dress, but he was sexually attracted to the girl herself. When she got the idea that he was trying to rape her, it might be she wasn't far from the truth--although Lennie himself probably didn't understand his own urges. George assumes that something similar happened with Curley's wife in the barn. Lennie didn't know what he was doing. Lennie is becoming a monster because he can't control his desires and his enormous physical strength.

Why are the rabbits significant to Lennie in Of Mice and Men?

Lennie is not only described as a person who likes animals (like rabbits, mice and puppies). He is also characterized as being animalistic (or animal-like). Lennie is repeatedly connected to the wild, natural world and shows that he can act instinctively and violently, as animals do. We might argue that Lennie is incapable of becoming truly socialized and so "belongs" to the animal world in some ways. 

This take on Lennie's character is not meant to be a harsh reading of a man that clearly has developmental challenges. Rather, it is simply a straight-forward way to answer questions as to (1) the nature of Lennie's connection to animal comforts (e.g. "soft things") and (2) the significance of the details associated with his character.

Consider Lennie's introduction in the text.

"[...] he walked heavily, dragging his feet a little, the way a bear drags his paws." 

In the following paragraph when Lennie reaches the brook he "drank with long gulps, snorting into the water like a horse." 

These specific details are reiterated and echoed again at the end of the novel when Lennie runs back to the brook after killing Curley's wife. There again he is depicted as an animal and compared to a bear. 

Lennie's connection to mice and puppies is explained in part via this metaphorical, animalistic characterization. Lennie has an affinity for animals because, in a figurative way, he has a kinship with them.

What is the significance of this kinship in the text? We might answer this question in a number of ways and you may have your own ideas about why Lennie's connection to animals (and a sort animalism) is important.

To briefly offer some ideas on this, we can read Of Mice and Men as a story of man's break from nature and/or read the book as a commentary on certain specific challenges placed on people living in a society where friendship is pitted against property ownership (and economic concerns). 

Reading Of Mice and Men as a story about a break from nature, we will pay close attention to the opening and closing sections of the work, noting how Lennie is characterized, how George and Lennie find peace in nature and how Lennie also threatens to run off to live in the wild. These details can be connected to an interpretation of the book wherein Lennie is a person who cannot successfully make the break from nature and who is incapable also of subduing his own inner-nature. He has no place in the society of the novel and no capacity to discover one.

"That Lennie has to die at the novel's conclusion is a poignant commentary on the inability of the innocent to survive in modern society" (eNotes).

Such a conclusion also aligns with a more Marxist interpretation of Steinbeck's work. Reading Of Mice and Men as a commentary on economic pressure as a stress on human relationships, we can look at the way friendships are often organized around the dream of property ownership. Lennie's love for soft things leads him to pet Curley's wife's hair then leads him to kill her as a way of protecting his one chance at continued friendship - the dream of the ranch that he and George often talk about. With this dream lost, the bonds that cemented the friendships between George and Lennie and Candy are (dramatically) severed. 

Why are the rabbits significant to Lennie in Of Mice and Men?

Literally, the reason that Lennie likes these kinds of small animals is that he likes to pet them.  In Chapter 1, that is what he talks about wanting to do.  We also see this because his Aunt Clara gave him a rubber mouse he did not like it because it was no good to pet.

I think that figuratively, this is meant to show how childish Lennie is and how much he depends on George.  He is so obsessed with little things that he can pet that he seems like a child.

Why are the rabbits significant to Lennie in Of Mice and Men?

Lennie is the ideal example of a gentle giant—and represents the dual nature of gentility and kindness in contrast with strength and destruction. Lennie is incredibly important to the story and is, in fact, probably the most critical piece.

Lennie is unintelligent and unable to comprehend many of his actions, but he is physically imposing and incredibly strong, able to crush bones with little effort. This leads him to crushing a man's hand, killing a puppy that he was petting, and accidentally snapping the neck of Curley's wife on the ranch.

He is shown as an example and archetype of an individual who intends well but causes destruction wherever he goes. In fact, his actions of good intention often result in death even though they are clearly done with good intentions. Lennie is important as the kind and naive individual who always sees the good in the world and believes that their dreams will work out—typified in the ending scene when he and George discuss their dream one last time before George has to euthanize him.

His strength and destruction seems to be an example of how good people sometimes make things worse, particularly for people in bad situations like the characters in the novel. They are all trying to remove their burden but accidentally make it worse through their actions in the book.

Why are the rabbits significant to Lennie in Of Mice and Men?

The image of the rabbit in Of Mice and Men is a symbol for George and Lennie's dream to own a ranch and "live off the fatta' the land." Throughout the novel, Lennie asks George to recount details of their dreams, and each time, Lennie focuses on his own role to tend the rabbits. Because Lennie focuses so much on this aspect, the image of the rabbits conjures images of the ranch and their dream.

Rabbits could also represent, on a bigger scale, failed dreams. George and Lennie have been working toward their dream to own their own ranch and look after themselves. They have to revise and adapt this plan as they go because Lennie continues to cause problems for them. In the first chapter, we learn that they had to leave their previous town because Lennie wanted to touch the soft fabric of a girl's dress, and the people misjudge his intentions and they are run out of town. This theme of failure is repeated throughout the novel, and in the end George and Lennie fail to reach their dreams. Because the rabbits represent their dreams, especially for Lennie, they also represent the failure of those dreams.

Why are the rabbits significant to Lennie in Of Mice and Men?

This strikes me as quite a thought-provoking question. Throughout Steinbeck's novel we find references to rabbits. Most of these references come from the little house that George and Lennie dream of having someday.

The part of their dream that most appeals to Lennie is taking care of the rabbits. Whenever George wants to punish Lennie, he threatens to take this job away from Lennie: “But you ain’t gonna get in no trouble, because if you do, I won’t let you tend the rabbits.” Whenever Lennie gets in trouble, he worries that George will not allow him to tend the rabbits.

So, on one level, the rabbits represent for Lennie the best part of their own personal utopia. On another level, the rabbits represent a mechanism by which George tries to control Lennie's behavior.

The rabbits also remind us of the soft things that Lennie likes so much. Unfortunately, Lennie's affinity for soft things gets him into trouble, as it did when he touched the woman's dress in Weed and when he touched the hair of Curley's wife. Steinbeck's word choice when George describes the reaction of the woman in Weed is quite ironic: "Well, that girl rabbits in an’ tells the law she been raped. The guys in Weed start a party out to lynch Lennie."

Lastly, we might also suggest that the rabbits remind us of Lennie's simplicity and the simplicity of what it would take to make Lennie happy. In contrast to human beings, rabbits seem like simple creatures. Lennie Small was a person with a simple mind who had a simple dream: he want to tend rabbits on a little farm with his friend George.

What is the significance of the mice, the dog and the rabbits in Of Mice and Men?

Candy's dog and the rabbits that Lennie dreams of tending are symbolic of the state in which these men live, representing the meager emotional world available to each man. 

When Candy is introduced in the book, he is a jovial but friendless and rather defeated person. His only comfort and friend is his dog, a nearly lame and stinking old canine. We can see parallels between Candy and his dog. 

Candy is the old, disabled ranch hand who is helpless to stop the shooting of his dog and who knows that he too will be banished when he is no longer useful.

The important fact of Candy's relationship to his dog, in the context of this question, concerns the isolation with which Candy is faced after his dog is killed. Though the dog was a burden to him, it was also his only attachment and comfort. Candy takes up a friendship with George and Lennie but there is no guarantee that this will last. 

For Lennie, the rabbits represent a role reversal for him as well as a fulfillment of a childish desire to be near soft things. In Lennie's dream of tending rabbits on a ranch of his own, he will be the caretaker - in contrast to his current state with George. 

We may see these attachments to animals as mere "creature comforts" craved by both men. However, in a world like theirs where friendships are often shallow and short-lived, their desire to own and care for animals represents a deeper lack of emotional security. 

What is the significance of the rabbit appearing at the end of Of Mice and Men?

At the end of the book, Lennie returns to the pool where the story began and takes a long drink. Then his aunt appears to him in his mind and lectures him for being a problem to George. Finally a giant imaginary rabbit that, significantly, talks in Lennie's voice appears to him. It symbolizes his conscience or super-ego and berates him ruthlessly for the trouble he has caused George. Through this rabbit, Lennie condemns himself harshly and imagines punishing himself by separating from George and going to live all alone in a cave. The rabbit torments Lennie, saying:

He's gonna beat hell outa you an' then go away an' leave you.

The imaginary rabbit repeats over and over that George is going to leave him, until Lennie puts his hands over his ears and cries out for George.

When George arrives and Lennie realizes he is not angry at him, the giant scolding nightmare rabbit goes away. It is replaced by its opposite, as George brings comfort, conjuring for Lennie the dreamscape of the farm full of rabbits. Now, the image of the rabbit represents the paradise of a better life on his own farm with George, living off the fat of the land.

Rabbits accompany Lennie, either in reality or his dreams, throughout the novella and represent both his self-loathing at the way he destroys dreams (just as he destroys rabbits) and the dream itself.

What do the rabbits symbolize in Of Mice and Men?

The rabbits in Of Mice and Men are very important to Lennie.  He is a gentle-hearted creature that longs for soft cuddly animals the same way a small child loves a favorite stuffed animal.  Unfortunately, Lennie is unable to control his considerable strength or to show restraint.  The small animals he pets (the mice and the puppy) end up dead.  The rabbits in the story are a metaphor for Lennie's dream for the future.

The rabbits in Lennie's mind represent a paradise.  Like children wanting to hear about Christmas, Lennie listens to George talk about the farm as a place where they both can be happy.  If he is good, he will live on the farm with George and have rabbits as friends.  However, if he does "a bad thing" he worries that this dream will not come true and George will not let him take care of the rabbits.  Such is Lennie's simplistic view of the world. 

At the end of the story, when Lennie kills Curley's wife, paradise has been lost.  The giant rabbit appears to Lennie, at the pool, and chastises him for being bad.  This is a nightmarish reversal of Lennie's dream.  The thing that has given him comfort in the past is now telling him all of his dreams have ended.  Though Lennie does not comprehend that he might be lynched, the loss of his paradise is devastating.