AUBURN, Ala. (AP) — Emma the miniature donkey runs around the barnyard and kicks playfully like most any animal her size. But she lacks one thing: A right hind leg.

Outfitted with a prosthetic limb shortly after birth, Emma has become a test case for veterinarians hoping to save the lives of horses, donkeys and similar animals that are typically euthanized because of leg deformities or fractures.

Born in April 2012 with a right rear hoof that wouldn't extend, Emma underwent surgery to amputate the limb at Auburn University when she was just a foal.

Today she's a healthy, active donkey with a 1,600-pound best friend — a horse named "Tank" — and a talent for kicking visitors with her pink prosthetic leg.

"That's how she plays. She does what any other donkey would do," said Dr. Jim Brendemuehl, a veterinarian who helps care for Emma at Auburn and owns her buddy Tank.

Emma has outgrown several prosthetic legs as she has grown.

The limbs are a combination of heavy-duty, molded plastic impregnated with carbon fiber for strength. To put the prosthetic on the donkey, handlers must fit Emma's stump with a sock and a rubbery sleeve before putting her leg back into the device. Then she can go for a walk.

Veterinary experts and students alike have learned important lessons from Emma, like how to place the sleeve in a way that her stump isn't irritated by sand when she lays down in the corral and rolls around while wearing the prosthetic.