Pea the Mare Just Became the First Horse Treated With Sound Waves Instead of a Scalpel

Virginia Tech researchers are testing histotripsy, a focused ultrasound technology built for human cancer, as a new way to destroy stubborn equine sarcoids. They're recruiting more horses now.

This spring, a 9-year-old Hanoverian mare named Pea stood quietly in the Virginia-Maryland College of Veterinary Medicine's Teaching Hospital while a device on her belly used sound waves to destroy a tumor, no scalpel, no general anesthesia, no water bath. It was the first live test of its kind, and Pea, by all accounts, could not have cared less.

The tumor was a sarcoid, the most common and most stubbornly hard-to-eliminate skin tumor in horses. Sarcoids form when bovine papillomavirus meets a horse's own genetic susceptibility, and left alone, they ulcerate, bleed, and attract flies. Standard treatment means surgery, often paired with chemotherapy, but plenty of sarcoids sit in spots too big or too awkward to cut, and the chemo itself carries real risk for the people handling it on a farm.

“There is no one-fix-for-all solution for sarcoids,” says Sophie Bogers, assistant professor of large animal surgery at Virginia Tech. In bad enough cases, she says, owners cycle through procedures and wound care for months or years, and some ultimately choose euthanasia over an endlessly recurring mass.

The technology Bogers is now testing on horses, called histotripsy, was originally developed at the University of Michigan to treat cancer in people. It uses focused ultrasound to generate a bubble cloud that breaks down tumor tissue from the inside. It reached Virginia Tech through biomedical engineer Eli Vlaisavljevich, whose lab spent years refining it for human liver, kidney, and pancreatic tumors, work that helped make Virginia Tech one of just 12 Focused Ultrasound Centers of Excellence in the world. Joanne Tuohy, a surgical oncologist at the veterinary college, had already been using histotripsy on cancer in dogs, which made horses feel like the next logical step, and a familiar one. Equine vets already reach for ultrasound constantly, so the underlying tool wasn't a hard sell.

Getting there took an engineering fix, too. Human histotripsy relies on a water bath to carry the sound waves into the body, which obviously doesn't work on a horse standing in a barn aisle. The team's solution was a solid, gel-based coupling pad, essentially the same technology used for routine ultrasound exams, swapped in to do the water bath's job.

Pea's owner, Kelly Kuykendall, wasn't looking for a clinical trial. Her longtime vet noticed a small growth on Pea's abdomen and started calling around for surgical pricing, and the search eventually led to Virginia Tech's study. Pea was hauled up from North Carolina, stayed overnight, and had the tumor removed the next morning. By lunchtime she was headed home.

“It's super cool that we get to help advance science,” Kuykendall says. She hadn't realized until she arrived that Pea would be the first horse in the trial treated while fully awake.

Bogers, who led the treatment, calls it a curative excision, with tumor destruction confirmed using both a handheld probe and a robotic positioning device. Pea tolerated the whole procedure standing and awake, with no apparent ill effects. Bogers and her team still need four more horses to complete this phase of the study before they know whether histotripsy can reliably keep a sarcoid from coming back, but a horse tolerating focused ultrasound awake and unbothered is itself a meaningful first data point.

Long term, Bogers wants a device portable enough to ride along in a truck, so a sarcoid can be treated the day it's found instead of months down the road, once it's grown, ulcerated, or turned into a bigger surgical problem than it needed to be.

She's also actively recruiting referring veterinarians, not just cases. “I would really like referring vets to know about this,” Bogers says, and she's willing to travel to meet a vet and horse on-site and walk through the technique together, in exchange for access to the tumor tissue for research.

WANT TO REFER OR ENROLL A HORSE?

Eligibility: the sarcoid must be fibroblastic or nodular type, not occult or flat, and must either be untreated in the past six months or have recurred after treatment.

Compensation: covers the consult, surgical fees, and up to $1,500 in hospital costs. Horses that don't qualify for live treatment may still be eligible for an ex vivo option, where the tumor is removed for lab analysis instead.

To enroll: contact Large Animal Services at the Virginia-Maryland College of Veterinary Medicine's Teaching Hospital at 540-231-4621. Be ready to email photos of the sarcoid, one from a distance showing where it sits on the body, and two close-up shots from different angles.

“I would say to go ahead and take care of it as early as you can,” Kuykendall says, looking back on Pea's case. “It's a win-win across the board, for horse owners, for doctors, and for advancement of equine welfare.”

Source: Virginia Tech and the Virginia-Maryland College of Veterinary Medicine. Photos by Madison Brown for Virginia Tech.