Castrating racehorses: A routine procedure not without its pitfalls
A recent study published in the Equine Veterinary Journal assessed the routine procedure of gelding and the complications associated with this procedure. The research was a retrospective study of horses castrated at the Sha Tin training complex in Hong Kong, between July 2007 and July 2012.
Hong Kong is a unique training and racing environment, and all horses training and racing there are imported, as there is no breeding in the region. Fillies are rarely imported. The majority of colts are castrated at some stage in their career, and open standing castration (OSC) is the method of choice by the vets of the Hong Kong Jockey Club (HKJC). Until now, nobody has looked at the prevalence of complications following castration of horses at the HKJC. This recently published study aimed to describe the prevalence and severity of complications in the 30 days following castration.
Reasons for gelding a racehorse in training
Most trainers perceive geldings as easier to train than colts, and if the horse has not shown enough ability for a stud career to beckon, there is little to lose by gelding. In Hong Kong, due to the unique environment the horses live in, there is an added incentive to geld these horses sooner rather than later. Once gelded, their management becomes significantly more straightforward.
Castration Method Options
Three surgical techniques are commonly used for equine castration: 1) open, in which the parietal tunic surrounding the testicle is incised and, usually, retained; 2) closed, where the portion of the parietal tunic surrounding the testis and distal spermatic cord is removed, and 3) half closed, where an incision is made through the exposed parietal tunic at the cranial end of the testis or distal end of the spermatic cord allowing the testis and part of the spermatic vasculature to be prolapsed through the incision prior to removal.
In most cases, racehorse castration is done standing via the open technique under local anesthetic, with sedation and pain relief as necessary. The testicles and spermatic cords are first injected with local anesthetic to numb the region. Once the tissues are totally desensitized, a slash incision is made into the scrotum. The testicle is exteriorized, and it is removed with a surgical instrument called an emasculator. The emasculator has a set of interlocking crushing blades with a cutting blade placed at the bottom of the array. Once the testicular cord is clamped in the emasculator the testicle will usually fall off, but the cord is retained within the interlocking crushing blades for approximately one to two minutes. This creates trauma to the tissues, which causes them to swell once the crush is released, reducing blood flow. The second effect of the emasculators is for the blood to be held in position long enough to begin the clotting process, which carries on once the clamp is removed.
An alternative method of castration is to anesthetize the horse and carry out the procedure with the horse on its back, as a completely sterile operation in an operating room. This has the advantage of minimal post-castration swelling as there is no infection in the area, which can be a common problem with standing open castrations. In horses who are cryptorchids (ridglings), which is when there is only one descended testicle in the scrotum, standard open standing castration is contraindicated. These horses require either castration under general anesthetic or testicle removal under standing surgery via laparoscopy (inserting a camera and instruments into the abdomen to remove testicle via a surgical incision).
Complications of Castration
As with all intrusive surgical procedures, there is the potential for things to go wrong. While the castration procedure is relatively straightforward, post-operative complications including excessive edema of the scrotum and surrounding tissues, infection and fever, hemorrhage, lameness, hydrocele formation, peritonitis, eventration, penile paralysis, scirrhous cord formation, and death have been recognized.
With castrations done under general anesthetic, there are all the attendant risks of putting a 1000lb animal on its back and up again. All anesthesia carries a risk of death in the horse. This has been calculated as approximately 1% in equine practice, and can be as low as 0.5% in the major well-equipped equine hospitals. In addition to this, occasional cases show prolonged bleeding after the surgery, which results in significant swelling that sometimes has to be resolved by opening the scrotal sac.
For standing castrations, some of the problems encountered include prolonged bleeding, which can occur irrespective of the length of time the cord has been clamped for. This can become serious enough to require a further surgery to identify the bleeding vessels and tie them off, but thankfully this is rare. Another rare complication is herniation of intestines through the potential space left in the inguinal canal with removal of the testicle. The intestines can either get trapped under the skin producing severe colic, or worse still, dangle out of the abdomen and become contaminated. This presents a very serious risk to the horse’s survival and requires immediate surgery to attempt to clean the exposed bowel and return it to the abdomen. Fortunately this is extremely rare in the Thoroughbred.
However, the most common complication is infection at the site of the castration. This procedure leaves an open wound and obviously the horse can lie down in bedding full of urine and feces on the same day it has been castrated, therefore potentially contaminating the open surgical site. Unfortunately many racehorses’ ability to be turned out in a paddock is often controlled by the training environment they reside in. Infection post-castration, and the added expense and lost training days associated with it, is a bugbear for trainers and vets, and this study reviews a common problem encountered worldwide.
Hong Kong Study
The Hong Kong training complex provides full-time stabling and training facilities to approximately 1250 horses spread out among 24 licensed trainers. The Department of Veterinary Clinical Services (DVCS) at the HKJC is the sole provider of veterinary care for this population. All clinical records of horses in training at the HKJC are collated within the Veterinary Medical Information System (VMIS). For a horse to be eligible for inclusion in the study, two testicles had to have been removed via an open standing castration. Veterinary records of all the horses that had been castrated were examined and any cases that did not meet the criteria were excluded.
Data on complications that occurred in the 30 days following castration was extracted from the clinical notes in the VMIS. The data was reviewed and the severity of complication was categorized into one of the five groups below:
Between July 2007 and July 2012, 280 racehorses in training were castrated. A total of 30 horses were omitted from the study, as they did not meet the inclusion criteria: 24 horses were castrated using general anesthetic, of which six were cryptorchid surgeries. Horses included in the study were in the care of 24 different trainers, with thirteen different veterinarians performing the castrations.
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