Out on a Limb: Young Burro Receives Artificial Leg at Colorado State

A five-month-old burro named Primrose got a leg up on life in the form of a prosthetic hind limb at Colorado State University recently, and her owner, a professional storyteller, put a happy ending on a sad tale.

After surgery and weeks of medical care at Colorado State’s Veterinary Teaching Hospital, the long-eared, waist-high, brown-coated Primrose got her new leg Aug. 31 under the supervision of Dr. Gayle Trotter, a Colorado State professor of clinical sciences who performed the amputation. With Trotter and clinical staff looking on, prosthetics technician Theresa Conrath performed the fitting and tryout in the hospital’s parking lot at the end of August before a crowd of reporters and television crews.

Primrose was three weeks old and living near Northglenn, Colo., the home of owner Bill Lee, when she was attacked by neighboring dogs. Lee, a storyteller, burro raiser and burro racer, sought veterinary treatment for the numerous bite wounds, but both hind legs became badly infected. He was referred to Colorado State’s College of Veterinary Medicine and Biomedical Sciences Veterinary Teaching Hospital for further consultation.

Trotter, a veterinary surgeon who specializes in horses, saw the animal in June and found that an infection, similar to a staphylococcus infection in humans, had reached the bone in both legs. The infection had so weakened the right rear limb that the bone cracked. Trotter, who had never amputated a burro or horse limb before, removed the leg below the hock.

"We used a recommended technique in amputations, salvaging soft tissues such as ligaments and tendons and wrapping them around the stump after rounding off the end of the bone," he said. "It provides better cushioning for the limb if soft tissue is available."

Trotter and Dr. Troy Trumble, a senior surgery resident at Colorado State, then fashioned a modified Thomas splint for the little animal, allowing her to walk as the wound healed.

Conrath, who works at Rehab Designs of America as a prosthetics technician, has a second business at home. She and her husband, Carl, run Veterinary Brace and Limb Technologies, making braces, prosthesis and orthotic devices for small animals. They’ve frequently worked with Colorado State veterinary faculty designing braces for dogs and orthotics for injured birds of prey being nursed back to health in Colorado State’s Raptor Program. However, Primrose’s two-pound, nylon-fiberglass-carbon fiber-and-acrylic-resin device was the first they’ve ever tried for a burro.

Carl Conrath, a former Rehab Designs worker who’s now completing a degree in animal science at Colorado State, said, "Everything we’ve done for Primrose was exactly what you would do for a person with, say, a below-elbow amputation, although for people the prosthesis doesn’t have to be as strong."

Primrose’s awkward gait in the parking lot was due to atrophied muscles in the long-immobilized stump, according to Theresa Conrath. She examined the burro a week later and reported it was already walking better, although "building up the muscles will be a long process." She gave Lee instructions for physical therapy on the burro but said, "I don’t know how much physical therapy can help, because Primrose is on that leg all the time, and once those muscles get tired, there’s little more you can do."

The couple will burro-sit Primrose in the near future to fine-tune the artificial leg, she said.

That pleases Trotter, who is impressed with the Conrath’s work but remains concerned. The problem with prosthesis on large animals such as horses and donkeys is that they’re not designed to walk on three legs, he said. Dogs, on the other hand, can often get around despite the loss of a hind leg and, for smaller canines, even a front one.

"Horses, and perhaps donkeys, can run into problems because they’re not built to accommodate weight the way an artificial limb forces them to," Trotter said. "If they are unable to readily use the prosthesis, they selectively bear weight on the opposite limb, which can either cause problems in that limb or make them want to lie down for longer and longer periods of time."

Prosthetics are occasionally used on horses that have value as breeding stock, he said. While he’s unfamiliar with prosthetics on donkeys – other than a burro whose leg was amputated above the hoof by two veterinarians, graduates of Colorado State – Primrose’s smaller stature may help, Trotter said.

The 49-year-old Lee, a longtime trail runner and ultra runner, began telling stories at Keystone Mountain resort a decade ago. He acquired so many props he bought an old donkey to help carry them and add color. The donkey proved useful, popular and appealing, and Lee now raises the animals. He also keeps dogs (his weren’t involved in the attack) who pull a sled when he portrays early 19th-century fur trappers. A herd of reindeer are part of the extended household. They haul a sleigh during the season when, as the slender Lee puts it, "My beard gets whiter, my eyes crinkle and I gain 100 pounds."

Lee, who notes that "I could have bought 30 burros for what I’ve spent on this baby so far," doesn’t regret his decision.

"Realistically, I should probably have put the baby down," he said. "But I felt responsible. I buy and raise these animals, and I feel I have to take care of them."

Lee said he is considering a proposal to write a book about Primrose, with proceeds to benefit children who themselves undergo amputations.