In the scene involving Curley's wife's death, Steinbeck includes many allusions to animals. What are these allusions, and what significance do they...

The allusions to animals in connection to Curley's wife's death are part of the Naturalism of Steinbeck's narrative.

Naturalism is a literary movement in which writers depict humans as having their fates determined by their environment. The naturalistic trope of Of Mice and Men—which is even suggested in the title—is that of the condition of the many dispossessed men of the Great Depression as being in a state no better than that of animals whose fates are determined by forces other than their own.

Certainly, Steinbeck foreshadows the accidental death of Curley's wife from the unwitting brute force of Lennie with the similar description of the death of the puppy by Lennie's hand. Suggestive of this naturalistic likening of Curley's wife's death to the puppy's death are the parallel descriptions of the two victims of fate after Lennie inadvertently kills them:

...he shoveled hay over the puppy with his hands.

Then:

Curley's wife lay with a half-covering of yellow hay.

Curley's wife dies after she enters the environment of the stall in which the huge man, whose arms swing at his side, sits with his dead puppy. This place is but an animal environment controlled only by naturalistic forces. Further, when Lennie is killed, it is a mercy killing by George that is not unlike Whitson's shooting of the dog, underscoring the naturalistic trope.