Answer:
I think the theme would be along the lines of division or judgment
Explanation: based on the quotes " they were all alike. No question, now, what had happened to the faces of the pigs. it was impossible to say which was which." and " he said, was happy that the period of misunderstanding was at an end. For a long time there had been rumours--circulated,"
let me know if its wrong sorry if it is I didnt have time to read the full book :)