Kentucky rancher Sharon Banford desperately wanted to save her thoroughbred, who had developed a massive jaw deformity. The horse's condition caused Banford to lie awake at night, plagued by the thought that her year-and-a-half-old filly would have to be euthanized.
But as fate would have it, her veterinarian knew of an unusual solution -- an experimental device created by Stanford Medicine bioengineers to treat severe bone injuries. The scientists were able to tailor the device, a scaffold made of a polymer-based material and embedded with regenerative proteins, to fit the horse's injured jaw. Within six months, the chestnut filly named Annunaki was on the road to full recovery and beginning to train for horse racing's bigtime.
"It was totally remarkable," Yunzhi Peter Yang, PhD, professor of orthopaedic surgery, said of the unprecedented procedure. "We customized our device and saved her."
Banford said she now hopes the next stop for the racehorse will be the famed Kentucky Derby.
Yang, who led the research team, first learned about the ailing horse through a colleague, Jeremiah Easley, DVM, a veterinarian at Colorado State University. For the last several years, the two had been testing the bone-healing device in sheep with leg injuries, with results showing vast improvement compared with standard surgery or drug treatments, said Yang, who has been developing the technology to one day help people with severe limb injuries. He began looking for other animals that could benefit from the approach.
Then last September, he got an unexpected call from Easley.
It was totally remarkable. We customized our device and saved her.
Yunzhi Peter Yang
"I remember the call very clearly -- it was my son's birthday," Yang said. "He told me, 'Peter, I may have a case for you.'"
Yang said the timing was auspicious: His son, who turned 9 that day, was born during the Year of the Horse.
A well-timed collaboration
Easley had learned about the stricken mare from his father, Jack Easley, DVM, a veterinary dental specialist practicing in rural Kentucky. Banford had turned to him when all other treatments had failed the horse, who had developed a cyst on her jaw after fracturing the bone in a fence accident. A local veterinary surgeon had removed the benign tumor, but it grew back even larger.
"It was about the size of half a baseball growing out of the side of her face," said Banford, a retired nurse and horse breeder who lives in Lexington.
The local veterinarians had nothing to offer other than euthanasia, so she begged Easley to take on the case.
"They had never seen anything like this in a horse before," Banford said. "I thought, 'Do I let her live until it becomes painful and then I euthanize her?' She hadn't shown any signs of pain, but it was growing. There were nights when I got so upset. She was so young."
She hadn't shown any signs of pain, but it was growing. There were nights when I got so upset. She was so young.
Sharon Banford
Jack and Jeremiah Easley discussed the case and felt like it was definitely worth a shot. So Jeremiah Easley called in the Stanford Medicine scientists, who frantically set to work on adapting their device to the horse. The vets supplied them with a CT image and a 3D model of the injured area, shaped like a lopsided rectangle, about 6 by 2 inches in size.
Yang and his team spent a month building a device fitted for Annunaki using a 3D printer. They created a porous scaffolding composed of a polymer and ceramic material. The material is designed to be gradually absorbed into the body.
The researchers embedded the scaffold with biological growth factors that are released over months to help build new bone and promote healing. These proteins also recruit stem cells to the site to aid healing, Yang said. While these sustained-release growth factors have been used in humans, they had never been applied to horses, Jeremiah Easley said.
Once the device was ready, Yang sent it by FedEx to Jack Easley's clinic in Kentucky.
A delicate surgery
A veterinary team of eight surgeons and anesthesiologists met up at a major equine center in Lexington for the complex procedure, which took place on Oct. 12, 2023. The surgery team included Brad Nelson, DVM, of Colorado State University, as well as Jack and Jeremiah Easley and other veterinarians and technicians.
After anesthetizing the 1,000-pound animal, the surgeons removed the diseased bone and tissue, then implanted the device into the large gap where they hoped new bone would grow. They used the remaining healthy tissue to close the wound. The entire process took about two hours, Jeremiah Easley said.
The horse recovered well, but developed a few localized infections that were successfully treated with antibiotics, Jeremiah Easley said.
"Once we got that cleared up, we saw there was a significant difference in the amount of new bone created in the defect site," he said.
Banford said the horse is back to her usual energy and eating normally. She's begun training her to race.
"Her jaw is a bit misshapen, but everything seems to work right," she said. "She accepts the bit in her mouth. She shows no signs of pain. It's all healed now."
Yang is thrilled with the result.
"Now she has 30 years ahead of her," he said. "We saved her life."
The experience has helped advance his research in treating people with critical bone defects that are unlikely to heal, he said. Thousands of patients every year lose major portions of an arm or leg due to infection, cancer or injury and have no options to repair the limb.
For example, patients with malignancies in the leg may have to have the cancerous bone removed. Sometimes reconstruction is possible, but often amputation is necessary, Yang said.
He's now looking into the possibility of clinical trials in a few years, with the prospect of making it available as a commercial product for improved treatment of patients with bone disorders.
In the meantime, he's hopeful there will be a Kentucky Derby trip in his near future.
"I'm so excited for that," Yang said of the possibility of seeing Annunaki run at the famed Churchill Downs. "I will go."
Photo: Courtesy Sharon Banford
