The results of a study examining the open standing castration technique for gelding horses suggest a review is warranted because of the high rate of complications and antimicrobial usage, according to researchers.
They found that 60 percent of the horses in the retrospective study who were gelded using the method suffered some level of complications within the 30-day window examined, with most being mild.
The study assessed the outcomes of 250 open standing castrations performed in Hong Kong between 2007 and 2012 at the Sha Tin training complex, which is home to about 1250 horses and the base for 24 licenced trainers.
In all, 13 different veterinarians undertook the surgeries.
Sarah Rosanowski and her colleagues, writing in the Equine Veterinary Journal, said complications following castrations using the technique in Thoroughbred racehorses were well recognised, but variations in their prevalence and severity between populations were not well documented.
The study team assessed veterinary records to determine whether horses had any complications, which they graded from none up to C3, which represented severe complications.
They found that 150 of the horses had experienced some type of complication following the surgery, with eight experiencing a severe problem requiring intensive veterinary treatment.
Of the 150 horses that experienced complications, 85 (56.7%) were classed as C1, 57 (38.0%) as C2 and 8 (5.3%) as C3.
Scrotal swelling was found to be present in 70% of these cases. Funiculitis − that’s inflammation of the spermatic cord − was present in 36.7% of the horses suffering complications, while seroma formation − fluid buildup under the skin − developed in just under a quarter of these cases.
The researchers found that 87.3% of the horses who suffered complications − that’s 131 of the 150 animals − required their wound reopened, while 44.7% required an extended course of first-line antimicrobials and/or non-steroidal anti-inflammatory drugs.
In total, five horses failed to return to galloping following the procedure for reasons unrelated to the surgery. Horses for which no complication was recorded returned to galloping a median of 29 days after castration – that is, half took longer than 29 days to return to galloping and half took less than 29 days. This extended to a median of 37 days for horses with complications.
The median for a return to racing was 95.5 days for those with no complications, and 108.5 days for those with complications.
“Complications following Open Standing Castrations in horses in Hong Kong were common,” they said.
They stressed that most of the complications were mild and were successfully treated using antimicrobials and simple wound management. However, given the high rate of complications and antimicrobial use identified in the study, a review of the technique was warranted.
They said that while the procedure was relatively straightforward, a range of post-operative
complications had been reported in previous studies, including death.
Previous research has shown that complications associated with castrating horses using the standing sedated method occurred in 16% to 22% of cases, compared to 6% to 10% when castration was carried out under general anaesthesia.
Rosanowski and her fellow researchers noted that the number of complications identified in their study were two to three times higher than those reported in other studies.
They said there could be several reasons. “There may be factors associated with the environment, such as type of bedding, sand on exercise tracks or climatic conditions that predisposed horses 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.”
They said further investigation of other potential risk factors, particularly stable management, was warranted.
It was also possible that the recording of complications was more comprehensive in Hong Kong than in previous studies, and using a higher threshold for the definition of complications (C2 and C3 only) would have meant a complication rate which was closer to other studies.
The study team said that while the prevalence of complications following the use of the technique was high, the vast majority were mild or moderate.
The severity of complications did not adversely affect the subsequent ability to race, they found.
Rosanowski, S., MacEoin, F., Graham, R. J. T. Y. and Riggs, C. M. (), Open standing castration in Thoroughbred racehorses in Hong Kong: Prevalence and severity of complications 30-days post-castration. Equine Vet J. Accepted Author Manuscript. doi:10.1111/evj.12758
The abstract of the study can be read here.