Adrian Gaut

MOLLY: APPALOOSA-SHETLAND PONY ——————————

LOCATION St. Rose, Louisiana

INJURY Lower leg amputated after a pit bull attack

Molly’s first prosthetic was made of acrylic, aluminum, and fiberglass; it was created by Gary Sod, a vet at Louisiana State University who was part of the team that amputated her leg to save her life. Her current prosthetic (shown), one of six she’s had over the years, was designed by Dwayne Mara of Bayou Orthotic & Prosthetic, who keeps making improvements to it. For his part, Sod is working on another approach: osseointegration—attaching the prosthetic directly to what remains of the bone—for large quadrupeds. He has successfully attached implants to bone and is experimenting with the best way to connect a prosthetic to the skin. He hopes to one day permanently affix artificial legs to the bones of horses and other creatures.

Molly was abandoned in the aftermath of Hurricane Katrina.

Check out the video: Animals in Motion—With Prosthetic Limbs

Adrian Gaut

WINTER: BOTTLENOSE DOLPHIN ————————–

LOCATION Clearwater Marine Aquarium, Clearwater, Florida

INJURY Caught in a crab trap that cut off circulation, she lost her tail and two vertebrae

To create a new tail for Winter, Kevin Carroll, a VP at Hanger Prosthetics and Orthotics and one of the world's leading prosthetists, and prosthetist Dan Strzempka worked with a chemical engineer to develop something they call Winter's gel. It's a rubbery sock made of thermoplastic elastomer. The trainer rolls it onto Winter's stump, then slips an anatomically correct tail (based on three-dimensional imaging of Winter's body) over it. The gel has been such a success that prosthetists, including some at Walter Reed Army Medical Center, have begun using it for human patients. Winter's gel, Carroll says, is softer and less irritating than other liners. It's especially helpful for keeping the prosthetics of amputee athletes in place when their skin becomes slick with sweat.

Winter is the subject of the movie Dolphin Tale, which came out in September.

Adrian Gaut

PENNY: WOLFHOUND —————-

LOCATION Alexandria, Virginia

INJURY Leg amputated after a bout with osteosarcoma (bone cancer)

Denis Marcellin-Little, a veterinary orthopedist, and Ola Harrysson, an engineering professor, both at North Carolina State University, have custom-designed prosthetics for a number of cats and dogs missing legs. Penny received a replacement limb about six months ago after bone cancer left her with three legs. Marcellin-Little designed the leg in conjunction with colleagues at Bio-Tech Prosthetics and Orthotics in Durham, North Carolina. The foam-lined prosthetic, made of thermoplastic, nylon, and Velcro, curves forward, which prevents it from getting caught on things like stairs. The rounded paw helps with shock absorption. Marcellin-Little is working on a study to determine how foot shape influences the gait of dogs with prosthetics.

Penny's young age and her playful, active disposition made her an excellent candidate for a prosthetic.

Adrian Gaut

CHRISIE: SANDHILL CRANE ———————–

LOCATION Save Our Seabirds, Sarasota, Florida

INJURY Leg amputated after a flying golf ball shattered the bone

Lee Fox, who runs Save Our Seabirds in Sarasota, Florida, got tired of euthanizing injured sandhill cranes. (The big-bodied, spindly- legged birds just can't manage on one leg.) So she became an ad hoc prosthetist, outfitting her one-legged sandhills with devices she jury-rigged out of PVC pipe and a sink stop. She heard about Kevin Carroll's work with Winter and invited him to come look at her birds. Carroll took plaster casts of two of the sandhills and fitted them with updated limbs. Today they strut around on his custom-designed creations like feathered Oscar Pistoriuses.

Chrisie's prosthetic is lined with the same gel used in Winter's tail.

Adrian Gaut

ZEUS: HUSKY ———–

LOCATION Southern Pines, North Carolina

INJURY Front paw ripped off by another dog

When Zeus was five weeks old, another dog attacked him, biting off his paw. The vet estimated his odds of survival at just 50 percent. But Zeus pulled through, and when he reached his adult size, his owner took him to see Marcellin-Little. The vet gave the dog an osseointegrated implant with an attached prosthetic, which he believed would provide the best mobility and a more natural gait. Marcellin-Little operated on Zeus' leg, implanting a piece of titanium that had been fabricated to match the shape of his limb. One end of the implant was anchored into the end of Zeus' bone, and the other end protruded out through the skin. Once the surgical wound healed, Zeus lost the temporary tennis ball and got his new foot—the prosthetic was screwed directly onto the titanium rod.

Within weeks of getting his new foot, Zeus was already chasing after squirrels.

Emily Anthes (emily@emilyanthes.com) is a freelance writer working on a book about animals and biotechnology.