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:     Group N     Group NEX     Group C1    Group C2    Group C3       No complications    No complications but received extended course of antimicrobials    Mild complications    Moderate complications       Severe Complications    (required urgent veterinary attention)       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.     Post-castration complications     Forty percent (100/250) of the horses experienced no complications. Sixty-six horses (26.4%) were categorized as N and 34 horses (13.6%) as NEX. There was no statistically significant association between a horse having a post-castration complication and horse signalment or the month, season, or year of castration.     Of the 150 horses that experienced complications, 85 (56.7%) were categorized as mild, 57 (38.0%) as moderate, and eight (5.3%) as severe. Most of the horses with complications had a record of scrotal swelling (70.0%; 105 horses), followed by funiculitis (inflammation of spermatic cord) (36.7%; 55 horses), and seroma formation (build up of serum within scrotum) (24.7%; 37 horses).     Antimicrobial use     Details of post-surgery medications were unavailable for six horses; therefore, data was analysed for 244 horses. One horse did not receive first-line antimicrobials at the time of surgery and another did not receive first-line antimicrobials but received reserved antimicrobials (enrofloxacin and ceftiofur).     Of the 244 horses, 109 (44.7%) horses received an extended course of first-line antimicrobials (Trimethoprim – Sulfadiazine or Oxytetracycline) and/or a NSAID (phenylbutazone or flunixin) for pain relief.     An extended course of first-line antimicrobials and/or NSAID was used in 48% (41/85) of horses grouped as C1, 53% (30/57) in the C2 group, and 50% (4/8) in the C3 group. Reserved antimicrobials were used in 42% (36/85), 81% (46/57), and 38% (3/8) of C1, C2, and C3 complications, respectively. Enrofloxicin and ceftiofur were both used in 22 horses, regardless of complication category.     Return to racing     In total, five horses failed to return to galloping after OSC. Horses for which no complication was recorded returned to galloping on average 29 days after castration. The interval was 37 days for horses with complications. Twenty-four horses did not return to racing. Horses returned to racing on average 95.5 days post-castration respectively.     Bacterial culture and sensitivity     Eight horses had samples collected for culture and sensitivity. Trimethoprim/sulfamethoxazole (TMPS) had been used prophylactically at the time of castration in seven of these and oxytetracycline in the other horse. Seventeen different bacterial isolates were cultured. Sensitivity testing showed that the bacteria cultured was resistant in vitro to commonly used front line anti-microbials oxytetracyclines, TMPS, gentamicin, metronidazole, and penicillin.  Bacteria cultured was sensitive to enrofloxacin in 13 out of 17 cases (76%) and all samples were sensitive to ceftiofur. In vitro, four of the six bacteria cultured were susceptible to the combination of gentamicin and penicillin.    Factors associated with complications    This retrospective study of clinical records from a closed population of horses found that 60% of all horses castrated in Hong Kong using the OSC technique suffered some type of complication within 30 days of the procedure. This is two-to-three times higher than has been reported in other studies utilizing survey-based data collection of veterinary clinical records. There are several possible explanations for the high prevalence of complications here.     It is conceivable that clinicians who undertook the procedures in this study had less ability or were less diligent in their practice than those involved in previous studies. This seems unlikely, as all the veterinarians who undertook these castrations were experienced and made every effort to practice to the highest standard.    Another possibility is that the surgical techniques practiced or the post-operative care were suboptimal. However, the OSC technique is relatively standard and varies little between locations, as does the post-operative care.     There may be factors associated with the environment, such as type of bedding, sand on exercise tracks, or climatic conditions, that predisposed to complications. The weather is hot and humid over the spring and summer in Hong Kong, which may be considered a risk factor for complications post-castration. However, analysis of the data revealed no association between month or season and rate of complication.     Another possibility is that the recording of ‘complication’ was more comprehensive here than in previous studies. A requirement to diligently maintain accurate clinical records together with daily attendance of stables by each veterinarian may have resulted in a greater proportion of horses with complications being recorded. This would be particularly pertinent with mild complications that may not have received veterinary attention in other populations.     While most of the complications were mild or moderate in nature, eight horses (3.2%) experienced complications that were graded as severe. The horses with mild to moderate complications were managed successfully with minimal intervention, including further antimicrobial and/or NSAID medication and wound drainage. The majority of horses with severe complications required hospital-level intervention. No horses castrated in Hong Kong over the five-year study period died due to complications associated with the OSC procedure.     In the cases where culture and sensitivity was performed, bacteria was identified that were resistant to a wide spectrum of antimicrobials, including those routinely used for prophylactic therapy during OSC. Ideally, antimicrobial therapy is based on findings from culture and sensitivity of bacteria involved. However, this approach requires delaying therapy at least 72 hours, and clinicians were cognizant that bacteria involved was most likely to be sensitive to enrofloxacin and ceftiofur. This is substantiated by the observation that these ‘reserved’ antimicrobials were effective at resolving infections, with or without culture and sensitivity results prior to treatment. Nevertheless, the use of antimicrobials, particularly those in the reserved category, needs to be protected.     While only 28% of horses with signs of infection had samples submitted for culture and sensitivity analysis, this study has identified potential patterns of antimicrobial resistance among bacteria involved in post-operative infection in this specific group of horses. The use of TMPS and oxytetracylines as first-line antimicrobials may be potentially contraindicated based on these limited results. Bacteria isolated showed greater sensitivity to a combination of penicillin and gentamicin than to TMPS and oxytetracyclines. In addition, this combination had a broadly similar in vitro sensitivity to enrofloxacin and ceftiofur.     Conclusion    This study is particularly useful, as the HKJC provides a unique opportunity to follow the outcome of horses after procedures like castration. However, the intensive housing of horses at the HKJC and the way they are managed means that the data should be interpreted with caution in relation to other locations. The prevalence of complications following OSC was high; however, the vast majority of complications were mild or moderate in nature. This study provides an opportunity to improve welfare and antimicrobial usage through an examination of existing OSC protocols in order to better inform future best practice.        Captions    Fig 1. Twenty-four hours after castration this horse has mild scrotal swelling, which would be classed as Group C1 in the Hong Kong study.       Fig 2.Fig 2. Tissues are prolapsing through the castration site - this severe castration complication requires immediate veterinary attention.

EUROPEAN EDITION - ISSUE 61 - APRIL TO JUNE 2018

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.

 Intestine is prolapsing through the castration site - this severe castration complication requires immediate veterinary attention.

Intestine is prolapsing through the castration site - this severe castration complication requires immediate veterinary attention.

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.

 

Twenty-four hours after castration, this horse has mild scrotal swelling, which would be classed as Group C1 in the Hong Kong study.

 

TO READ MORE --

Buy this issue in print -

April - June 2018 issue 61 (PRINT)
6.95
Quantity:
Add to Cart

Are you a subscriber?

Don't miss out and subscribe to receive the print magazine now! 

Print & Online subscription
24.95 every 12 months
Add to Cart

Equine Herpesvirus-1 : An Elusive Target

Amateur Riders - More than just a tradition

0