Philip K. Dick 
Beyond Lies the Wub 

In Beyond Lies the Wub, the crew of a spaceship buys a wub, a large pig-like animal from a native martian to eat on the way home. The Wub turns out to be a sentient being capable of intelligent conversation, empathy, and possibly telepathy and mind control. When a crew member converses with the remarkable Wub, the captain makes a rash and violent decision that could put the return mission in danger.