Simple, Matter-of-Fact
There's a reason Animal Farm is written in such a friendly style: Orwell was super suspicious of intellectuals. You might have picked up on that, what with the pigs being so shady. He was particularly skeptical of sophisticated arguments and fancy writing, which he figured people could use to disguise really unsavory actions.
Check out the description of Boxer's removal:
Boxer's face did not reappear at the window. Too late, someone thought of racing ahead and shutting the five-barred gate; but in another moment the van was through it and rapidly disappearing down the road. Boxer was never seen again. (9.24)
You guys, this is heart-wrenching, like watching our poor childhood dog—old, paralyzed, and toothless—driving off in the back of our parents' car to be put down. (What, just us?) But Orwell doesn't bother with sentiment or flowery language. There's no description of what the animals felt or how they panicked or moralizing about the situation. We just learned that they thought to close the farm gate "too late." Simple, sure—simply powerful.