November 2020

In today’s VETgirl online veterinary continuing education blog, we welcome our first large animal veterinary blogger, Kathryn M. Slaughter-Mehfoud, DVM, MPH. She is currently an equine surgical resident at University of Illinois.

Five Mistakes to avoid with Equine Field Castration
By Kathryn M. Slaughter-Mehfoud, DVM, MPH

Castration is the most common surgical procedure performed on the equine patient. An intact male horse requires substantial management requirements. These include specially trained personnel that can handle stallion behavior and strength, as well as adequate fencing to separate intact males from females. Owners routinely elect to have their colt or stallion “gelded” to decrease poor and unmanageable behavior traits and to remove the potential for the horse to breed. Other testicular pathologies, such as neoplasia, orchitis, torsion of the spermatic cord, and inguinal herniation can also lead to the decision to castrate the horse. Although castration is routinely performed by equine practitioners, complications following the surgical procedure are common and can be fatal. An equine field castration should never be viewed as a “simple castration.” Having worked at both private and University surgical referral hospitals, complications associated with equine field castration continue to be a common referral. The following are five mistakes to avoid with equine field castration: inadequate injectable anesthesia; removing one testicle; incising the penile shaft; not ligating the spermatic cord; and not removing protruding scrotal fascia.

Inadequate injectable anesthesia can instantly turn a smooth castration into a nightmare. With appropriate anesthesia, castration should be able to be completed within 15 minutes. An appropriate anesthetic protocol includes sedation with an alpha-2 agonist and an opioid, which increases the synergistic effects of the two drugs. Induction with ketamine and a muscle relaxant, such as diazepam, is recommended. Use reasonable judgement when assessing weight and calculating drug dosages. An underdosed horse that suddenly moves, kicks, or stands during castration is not only dangerous to the veterinarian and assistants, but can be life threatening to the horse. No veterinarian ever wants to see a horse running around the field with a hemorrhaging testicular artery that was not ligated.

As a veterinarian at a surgical referral hospital, I plead with you, do not remove just one testicle! If the veterinarian induces anesthesia and can only palpate one testicle, the horse should be recovered from anesthesia without surgery. Removing one testicle does not accomplish the goals of castration, which primarily include removing the potential of the animal to breed and decreasing stallion behavior. The horse will still be able to reproduce and behavior will be unchanged. In addition, it is unwise to trust the owner will rightfully bring the horse to a surgical referral hospital to remove the missing, likely abdominal testicle. In the past three years, I have witnessed over a dozen owners bring their newly purchased “gelding” for evaluation of stallion-like behavior. Hundreds of dollars invested in hormonal assays and ultrasound examinations later, the owner is surprised to learn they were duped into purchasing a stallion. As a rule, I always recommend removing the smallest or questionable testicle first. If the practitioner cannot find the “high flanker,” the horse should be recovered without removing the other larger or obvious testicle. If the practitioner removes the larger testicle first and then cannot find the smaller testicle, the goal of the procedure has failed.

Image by greb from Pixabay

Accidentally incising the penile shaft is also a common complication of equine castration, especially if the horse has one or two small testicles. When performing castration on a horse with a small testicle(s), always have a gloved assistant retract the penis out of the prepuce. This allows the veterinarian to clearly visualize and palpate the scrotum and inguinal region without accidentally incising into the penis. When the penis is retracted into the prepuce, it can coil in a way which appears and palpates like a testicle. By exteriorizing the penis from the prepuce, the veterinarian can be confident their blade is not incising into the penis.

The most common emergency I have witnessed which presents following field castration is hemorrhage of the testicular artery due to lack of ligation of the spermatic cord. Many veterinarians only rely on emasculators to provide adequate hemostasis to the remaining spermatic cord. Although many veterinarians routinely castrate stallions without the use of ligatures, the horses that would have benefited from ligating the spermatic cord can die due to excessive hemorrhage. The risk of hemorrhage may appear low to practitioners, but the horses that do bleed are at risk of dying if the vessel is not ligated. A single, or in some cases double, transfixation ligature proximal to the placement of the emasculators is strongly recommended to avoid any excessive hemorrhage from the testicular artery. The placement of one transfixation ligature on each testicle will not “waste” time on the injectable anesthesia. The ligatures are worth the investment of one minute.

Following removal of the testicles from the scrotal incisions, any fascia which protrudes from the scrotum should be removed. Protruding scrotal fascia is a direct pathway for pathogens from the outside environment to enter the scrotal and inguinal region, leading to septic funiculitis. Antibiotic therapy is always warranted in cases of septic funiculitis, and in some instances surgical debridement. I strongly recommend practitioners take one minute at the conclusion of castration to trim away protruding scrotal fascia to prevent this painful, expensive complication.

Equine field castration will continue to be one of the most common surgical procedures performed by ambulatory practitioners. Any surgical procedure, including the routine castration, should never be taken lightly. When complications do occur, not only does this cause frustration and added expense to the client, but the horse’s quality of life is also decreased. Avoiding these five mistakes in equine field castration makes for happy clients and healthy gelded horses!

  4. Kristina Van Horn says:

    Agree about the tip regarding extruding the penis, will be handy when I start gelding weanlings. I had a 2 yr old colt hemorrhage several years ago – he did nearly die – I elected to close the scrotum temporarily to provide pressure. It saved his life, but he did need a lot of follow up care and “re-opening.” He is fine today, thank god.

  5. Meghann Bothe says:

    Great article! We have a gelding that we think may not have been properly gelded. It makes me want to be more aware of questions and procedures used when gelding.

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