Although many people think Animal Farm is a direct attack on Communist Soviet Union, he actually uses the Soviet's as an example to show the danger of totalitarian governments and that corruption is inevitble when one becomes too powerful. He also wants to warm readers about the dangers of revolutions and how they more often amount to pointless violence as the new government becomes even more corrupt than the original government once it gets its taste of power. The pigs in the story prove all of this, as they originally set out with the goal of improving the farm; however, they soon lose their way and take advantage of the lesser animals when it benefits them to do so. By the end of the book, the pigs (the new government) are no different than Mr. Jones (the old government). Consequently, life on Animal Farm for all the animals except the pigs and the dogs are no better, arguably worse, than they were before the Animal Revolution.
Simply put, Boxer is Orwell's major concern in his work. The idea of the loyal subject, an individual whose only concern is "to work harder" is of significant concern to Orwell. The fact that Boxer strives to "work harder" and then is "rewarded" for his efforts with a sale to the glue factory, sealing his doom is something that Orwell sees as representative of the future in terms of the relationship between government and governed. Naturally, Animal Farm is a representation of the Soviet Union. Yet, there is a larger concern for Orwell in the way in which individuals place trust in their government. The idea of blind faith and loyalty, along with the refusal to question authority is something that concerns Orwell. The idea that individuals can be sheep, literally and figuratively, causes significant worry in Orwell. The ending of the book where the animals literally cannot tell the difference between humans and pigs is something that Orwell feels lies at the heart of all political orders that believe they are able to manipulate the will and heart of the people. In order to avoid this state of affairs, Orwell demands a sense of questioning and accountability between people and their government.