It is mentioned in the text that though they were concerned about the effect of the rebellion on their own animals, Pilkington and Frederick "disliked each other so much that it was difficult for them to come to any agreement, even in defence of their own interests" (12).
As you probably already know, Animal Farm is an allegory for the Russian revolution. Farmer Jones' neighbor's, Frederick and Pilkington, loosely represented Germany and England, respectively. These countries (at the time Orwell wrote the book) were at war with one another (hence the mutual dislike), while England and Russia were allies. This made it difficult for the British Orwell to get this book (a serious criticism of Soviet Russia) published.
Additionally, the text tells you that most of the other farmers were secretly hoping that " he could not somehow turn Jones's misfortune to his own advantage" (12).