horse castration complications

In theory—and in many cases—castration is a straight forward procedure: sedate or anesthetize horse, remove testicles, and use proper precautions to help the recovery go smoothly. But not all horses have it so smoothly. In fact, researchers have learned that some horse breeds appear more prone to complications, the most serious of which is evisceration—when the intestines protrude through the surgical site—which can be fatal if not promptly treated at a surgical facility.

John Haffner, DVM, an associate professor at Middle Tennessee State University, in Murfreesboro, wanted to learn more, so he conducted an online survey of veterinarians about their experiences castrating horses. He shared the results at the 2018 American Association of Equine Practitioners Convention, held Dec. 1-5 in San Francisco, California.

“If we know which breeds and methods are more prone to evisceration, we can be better prepared for complications,” he said.

Haffner and colleagues Gema Vidal, DVM, MPVM, and Eric W. Davis, DVM, MS, Dipl. ACVS, ACVIM, looked at three variables:

  • Horse breed;
  • Castration method—emasculation (crushing the spermatic cord, which is supplies blood to the testicles, before removing them) or twisting (using a tool that rotates, severing and sealing the spermatic cord and removing the testicles); and
  • Surgery position—standing or recumbent (lying down).

He said the team ended up with usable responses from 144 veterinarians. Some of the key findings:

  • The veterinarians performed 41,664 castrations over the previous 10 years;
  • Eviscerations were uncommon. In all, they reported 82 (0.2% of patients);
  • Of the breeds reported, Standardbreds, Saddlebreds, and “other” breeds (which included donkeys, mules, Hackneys, Warmbloods, Andalusians, and Paso Fino-types) were more likely to experience evisceration, while Thoroughbreds and Quarter Horses were less likely;
  • Veterinarians reported castrating horses standing in 80% of procedures and recumbent in 20%, and they reported evisceration in 65 standing horses (0.65 per thousand castrations) and six recumbent horses (1.84 per thousand castrations); this means horses were 0.35 times less likely to eviscerate if they were gelded standing versus lying down; and
  • Practitioners used emasculation in 90% and twisting in 10% of procedures, and they reported evisceration in 51 emasculator horses (1.21 per thousand castrations) and 11 twisting horses (2.48 per thousand castrations); this means horses were 2.09 times more likely to experience evisceration when gelded using twisting than if they were gelded using emasculation.

Haffner said it’s unclear why standing castrations and emasculations are less likely to eviscerate.

He also said this survey didn’t take practitioner experience—with the techniques or overall in their career—into account. “In future studies experience should be evaluated,” he said.

In the meantime, he recommended veterinarians take breed, castration technique, and surgical position into consideration when gelding horses.