It was just after the sheep had returned, on a pleasant evening when the animals had finished work and were making their way back to the farm buildings, that the terrified neighing of a horse sounded from the yard. Startled, the animals stopped in their tracks. It was Clover's voice. She neighed again, and all the animals broke into a gallop and rushed into the yard. Then they saw what Clover had seen.
It was a pig walking on his hind legs.
George Orwell, Animal Farm