Sheep are way better than cats or dogs. They can be trained to walk on a leash, they come when called, they can be very affectionate and they eat…
Tangent, tangent, cosine, sine! Three-point-one-four-one-five-nine! CalTech! CalTech! Rah!
A Left-Handed Sword by Phil Geusz, though it's really more of a long short story.