Original Article Comparison of the use of a braided multifilament transfixation suture for field castration with other castration techniques J. B. Koenig † * , M. Sinclair † and U. S. Sorge ‡ † Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada; and ‡ Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St Paul, Minnesota, USA. *Corresponding author email: jkoenig@uoguelph.ca Keywords: horse; castration; complications; transfixation; suture Summary Complications with castrations occur commonly and are usually not life-threatening, with the exception of evisceration or haemorrhage, which are uncommon. Primary closure castration (closing deeper tissue layers and skin) or use of a transfixation ligature alone to prevent evisceration has been recommended. The goal of this study was to investigate the use of a closed technique with multifilament suture for transfixation of the spermatic cord alone in field castrations. The results of this study support our hypothesis that a closed castration technique with a multifilament, transfixing ligature (No. 2 polyglactin 910) did not result in additional post- operative complications when compared with a closed castration technique without ligature placement or a primary closure castration technique in a hospital setting. Introduction Castration is one of the most common surgical procedures performed in male horses. The procedure can be performed with the horses either standing under heavy sedation with local anaesthesia, or in recumbency under general anaesthesia. Open, closed and semiclosed surgical castration techniques are used for horses with or without primary wound closure (Cox 1984; Searle et al. 1999). Choice of anaesthetic and surgical technique vary based on the surgeon’s preference, practice tradition, owner’s desire, behaviour of the horse, descent of the testicles and surgery location (field or operating room) (Pleasant 1999). Complications that have been reported following castration include scrotal swelling, oedema, haemorrhage, omental herniation, evisceration, penile trauma, bacterial infection of the spermatic cord (scirrhous cord formation or funiculitis), incisional infections, hydrocele formation and peritonitis (Thomas et al. 1998; Pleasant 1999; Searle et al. 1999). Certain breeds such as Standardbreds and draught horses have been reported to be more prone to omental herniation and evisceration following open and closed unsutured castration techniques (Shoemaker et al. 2004). Therefore, ligation of the spermatic cord or primary closure castration has been recommended to possibly reduce the risk of post-operative complications (Moll et al. 1995; Schumacher 1996, 2012). Primary closure castration typically requires referral to a surgical facility and is costlier than ligation of the spermatic cord alone (Mason et al. 2005). In a recent study, 6–9 months old colts castrated utilising a closed technique and a pretied monofilament suture under field conditions were reported to have low post-operative infection rates (Carmalt et al. 2008). Use of a monofilament transfixation suture and emasculators increased parietal tunic tensile strength and may reduce the risk of evisceration (Rijkhenuizen et al. 2013; Comino et al. 2016). Monofilament suture would be desirable to use under field conditions due to minimal tissue drag and a reduced risk of infection, but increased bending stiffness and memory are associated with poorer handling properties and reduced knot security (K€ ummerle 2012), which could outweigh the benefits. Multifilament suture, particularly polyglactin 910, is easier to handle and less likely to break. Along with these properties, it has a greater initial breaking strength than monofilament suture (K€ ummerle 2012), making it a more secure suture to use for castrations. Few reports outline surgical characteristics of suture type and post-operative complications in colts for castrations. Therefore, the goal of this study was to investigate the use of a closed-castration technique with a multifilament suture for transfixation ligation under field conditions. We hypothesised that using multifilament (braided) suture material under field conditions (Group 1) would not result in an increase in post-operative complications compared with a closed field castration technique without suture (Group 2) or a primary closure castration approach in a hospital setting (Group 3). Material and methods Animals A total of 90 horses were placed into three separate surgical castration groups (30 horses each). All colts were deemed healthy based on a physical examination and the scrotum was palpated to ensure both testicles were present prior to surgery. Group 1 (n = 30) were part of a prospective randomised clinical trial about parallel field anaesthesia and were included in the closed castration with transfixation suture group (Sinclair et al. 2013). All procedures were approved by the Animal Care Committee, University of Guelph, and followed the Canadian Council on Animal Care Guidelines with owner consent. Surgeries were performed over a 2-year period in the spring and fall (2012 and 2013). Other horses were included to compare surgical complications retrospectively as follows: medical records of horses undergoing castration at the Ontario Veterinary College (OVC) over a 3-year period (2012–2015) were © 2017 EVJ Ltd 1 EQUINE VETERINARY EDUCATION Equine vet. Educ. (2017)  () - doi: 10.1111/eve.12816