If you are writing a paragraph on the spread of the revolution to other places, then you are writing on a topic that has been hinted at in the book already. Here is what Orwell states about the spread of the revolution though other animals.
It had spread with astonishing speed. The human beings could not contain their rage when they heard this song, though they pretended to think it merely ridiculous. They could not understand, they said, how even animals could bring themselves to sing such contemptible rubbish. Any animal caught singing it was given a flogging on the spot. And yet the song was irrepressible. The blackbirds whistled it in the hedges, the pigeons cooed it in the elms, it got into the din of the smithies and the tune of the church bells. And when the human beings listened to it, they secretly trembled, hearing in it a prophecy of their future doom.
Now if you want to elaborate on it, then you can be creative. For example, you can talk about how the pigs used pigeons to communicate with other farms to keep the revolution going on a more massive scale. Why stop with one farm, when you can reach many others? Also you can describe stories of success and stories of failure. In the same vein, you can use other birds as well. For example, Moses was a raven with a vision of Sugar Candy Mountain, but you can give him a different message, or give other birds different messages as well.
Much of this is also grounded in "real life," because people use pigeons to carry messages. So, you would work with the tenor of the book.