From MTG Salvation Wiki
Kithkin knight riding a springjack. Art by Wayne Reynolds.
Springjacks are small grazing animals native to the
plane of
Lorwyn. They resemble goats or sheep with slightly curving horns, shaggy wool, and four-clawed paws.
Kithkin keep springjacks for use as mounts, as well as for their milk, mutton, and wool. Those who tend flocks of springjacks are known as jackherds.