In Through the Looking-Glass, a sheep runs the shop Alice visits.
Alice reaches the shop during the chapter “Wool and Water,” after travelling with the White Queen. In a characteristically unstable Looking-Glass transformation, the White Queen suddenly becomes a talking sheep. Alice finds herself inside the Sheep’s shop, surrounded by shelves whose objects shift whenever she tries to focus on them.
The shop soon turns into a boat on the water, and the Sheep gives Alice knitting needles that become oars. The Sheep’s comments about “feathers” and “crabs” use real rowing terminology: feathering means turning the oar blade nearly horizontal during recovery, while catching a crab means getting the blade stuck in the water.
After the strange boating episode, Alice returns to the shop and buys an egg from the Sheep. That egg later becomes Humpty Dumpty, linking the shop scene to the nursery-rhyme characters Alice meets next. The animal is therefore specifically a sheep, not a goat or cow.