The use of the Stone Henderson Equine Castration Instrument, which allows veterinarians to geld colts using an attachment on a battery-powered drill, has gained speed since its debut at the 2005 American Association of Equine Practitioners’ Convention. John Steiner, DVM, Dipl. ACT, of Hagyard Equine Medical Institute, reviewed the tool’s anecdotal reports of successful use during the Hagyard Bluegrass Equine Symposium, held Oct. 18-21 in Lexington, Ky.

A veterinarian using the Henderson Instrument positions the horse in lateral recumbency after employing commonly used general anesthetic. He makes a standard castration incision over the testicle, exposing the testes, leaves the vaginal tunics (which surround the testes) intact, and he strips away the fascia (the whitish tissue that connects muscles to subcutaneous tissue or binds muscles together in bundles) to expose the spermatic cord. After placing the instrument on the exposed cord, very close to the testicle, he connects the instrument to a cordless drill.

“It’s important that it’s at least a 12-watt variable speed drill, or it will slip,” said Steiner, “and a detachable chuck is helpful.” Clockwise rotation of the drill with the device twists the spermatic cord until it fractures, then the veterinarian removes the testicle. “Be careful and start the rotation slowly, and don’t yank on it,” Steiner said. “It takes 20-25 turns and cuts off the vascular tissue, and there’s very little–if any–hemorrhage or swelling. Theoretically, it should prevent any evisceration (protrusion of other organs from the surgical site).”

Veterinarians on 6666 Ranch in Texas reportedly used the new technique to castrate 36 colts in one day, and the colts were turned out and recovered without incident. Anecdotal experience among the listeners at the Symposium revealed that some veterinarians perform the procedure with the horse sedated and standing