Three examples of the pigs using rhetoric to oppress the other animals in Animal Farm are when Squealer utilizes antithesis, hypophora, and anacoenosis. The pigs prove to be very capable rhetoricians, as they utilize rhetoric as a means of manipulation and control.
Antithesis involves the juxtaposition of two contrasting ideas. Early on in Animal Farm, in the process of streamlining the tenets of Animalism, Snowball further crystalizes these ideas contained into the antithetical maxim "four legs good, two legs bad." However, as the book continues, Snowball's political enemy, Napoleon, weaponizes the slogan, using the sheep, who have a noted tendency of repeating the slogan ad nauseum, as a disruptive force among political meetings and discussions. It is an effective and powerful slogan and rallying cry, but its own rhetorical advantages allows for its later weaponization.
Meanwhile, hypophora involves the strategic raising of a question by the rhetorician so that they can then answer it on their own terms. This is a favorite trick of Squealer's. For example, when the other animals discover that the pigs had taken the milk, Squealer responds in the following fashion:
You do not imagine, I hope, that we pigs are doing this in a spirit of selfishness and privilege? Many of us actually dislike milk and apples. I dislike them myself. Our sole object in taking these things is to preserve our health. (Chapter 3)
Through the use of this rhetorical device, Squealer is able to hijack any criticism against the pigs in order to take control of the conversation. Later, you will see this same technique used when the pigs come under criticism for sleeping in beds, to which Squealer makes the following reply:
And why not? You did not suppose, surely, that there was ever a ruling against beds? A bed merely means a place to sleep in. A pile of straw in a stall is a bed, properly regarded. The rule was against sheets, which are a human invention. We have removed the sheets from the farmhouse beds, and sleep between the blankets. (Chapter 6)
Again, Squealer is raising this question so that he can then answer this criticism on his own terms, manipulating it so that he can outmaneuver dissent.
Finally, anacoenosis involves the use of a rhetorical question, by which the rhetorician appeals directly to their audience, even while phrasing that appeal in terms that coerce agreement and discourage dissent. This is another technique used by Squealer, as he asks the other animals the rhetorical question, "surely none of you wishes to see Jones back?" This is a question he asks on multiple occasions, but each time it is posed, there is only one answer. Thus, whenever he raises this question in these terms, it amounts to an act of coercion, delegitimizing any criticism or opposition and forcing their submission.