The animals in the other farms react in a mixed way. At first Mr. Pilkington and Mr. Frederick, the owners of the adjacent farms, are very worried that the rebellion would spread. There is some evidence that this would happen as other animals learned the song "Beasts of England." What made this situation even scarier is that the animals began to sing it. The implication is that there will be a rebellion.
When Mr. Pilkington and Mr. Frederick come to understand the situation, they counter any potential rebellion by spreading rumors that the situation on the farm was horrible. The animals, in other words, were not faring well at all. They said that the situation was dire. It seems that most of the animals believed them, as they did not revolt.
However, a few animals did try to help. For example, when Mr. Pilkington and Mr. Frederick began to march to attack the farm, pigeons flew over to Snowball and Napoleon to warn them about the attack. This is why the animals were prepared.
In conclusion, most animals wanted to revolt, but a mass revolt did not happen.