Science1 publisher3 min readPublished
A gel coupling pad carried histotripsy to a sarcoid on one standing mare
Virginia Tech engineers and veterinarians swapped the water bath that human histotripsy needs for a solid ultrasound gel pad, then treated a nine-year-old Hanoverian mare who stood awake through the session. The trial has one horse in it so far.
The Scientist · Science desk
What happened
- A Virginia-Maryland College of Veterinary Medicine trial ran its first live test of histotripsy this spring on Pea, a nine-year-old Hanoverian mare with a tumor on her belly.
- Human histotripsy couples the transducer to the patient through a water bath, which a standing horse cannot use, so the team substituted a solid gel-based pad of the sort sold for routine scans.
- The mare tolerated the session standing and awake with no apparent ill effects, which is the one clinical observation the team says it now has in hand.
- Sarcoids are normally cut out, often with chemotherapy alongside, and many of them sit in places too large or too awkward for surgery.
Compiled by The ScientistSomething wrong?How this is made
Why it matters
- capability Coupling through a gel pad puts the treatment where horses already stand for diagnostic scans, so a stall or a barn aisle becomes a possible treatment site instead of a surgical suite.
- exposure A purely mechanical ablation shifts risk off the handler. Cytotoxic drugs expose the person holding the syringe, and a farm has none of a hospital's containment.
- decision A truck-portable unit would change what a first-visit veterinarian can offer, moving the choice from booking surgery weeks out to treating a small lesion on the spot.
- constraint The next device has to be both more powerful and still carryable, and whichever requirement gives way decides whether this stays a referral-hospital procedure or becomes ambulatory practice.
Sound does not cross air, so histotripsy needs a continuous path of something that carries pressure waves from the transducer into tissue. In people that path is a water bath, and a water bath does not work on a horse that is standing up [5]. The substitute was a solid, gel-based coupling pad, the kind already used for routine diagnostic ultrasound [5].
Familiarity is part of why that route is plausible in the field. Equine practice already runs ultrasound daily. "We do ultrasound on horses all the time, and equine practitioners are very comfortable with ultrasound," Sophie Bogers, an assistant professor of large animal surgery, said [6].
Pea stood for it. "She was really good about it," Bogers said. "She just stood there, was very happy. She didn't seem to feel or dislike the histotripsy" [7]. That is a tolerability observation in one mare. The researchers say they do not yet know whether histotripsy can reliably keep a sarcoid from coming back [9]. With a single treated animal there is no comparison group and no recurrence rate to report [10]. The team did not report how much tumor tissue the bubble cloud broke down.
Sarcoids form when bovine papillomavirus meets a horse's own genetic susceptibility [11]. Standard treatment is surgical removal, often paired with chemotherapy, and plenty of sarcoids sit in spots too big or too awkward to cut [12]. Chemotherapy carries risks for the people delivering it, especially in a farm setting [13]. When a lesion keeps returning, owners can cycle through procedures, wound care and expenses for months or years with no resolution [14].
"In some cases for large sarcoids, people find the management of the sarcoid becomes too much, and they elect euthanasia," Bogers said [15].
The technology itself is borrowed. Histotripsy was developed at the University of Michigan to treat cancer in people [3], and Eli Vlaisavljevich's lab has spent years refining it for human liver, kidney and pancreatic tumors [4]. Joanne Tuohy, an associate professor of surgical oncology at the veterinary college, had already been using histotripsy against cancer in dogs, and Bogers said that is what made horses feel like an obvious next step [16].
Engineers are now building a version that delivers stronger energy while staying portable [17]. Bogers wants a device that can ride on a truck, so a sarcoid can be treated the day it is found instead of months later [18].
Pea reached the trial by an ordinary route. Her veterinarian noticed the small growth on her abdomen and started calling around for surgical pricing, and her owner, Kelly Kuykendall, hauled the mare up from North Carolina [19]. "My vet called me back within a couple hours and she said, 'I've got great news. If you want to participate in a study, you can get this whole entire thing removed for free,'" Kuykendall said [20].
What to watch
- Whether later horses in the trial show sarcoids staying gone, and at what follow-up interval the team reports it.
- Whether the stronger applicator the engineers are building stays light enough to ride on a veterinarian's truck.
- Whether the team publishes ablation volumes and histology from the treated site rather than tolerability alone.