A 4-year-old Arabian gelding weighing 379 kg (834 lb) was referred to the Washington State University Veterinary Teaching Hospital for evaluation of an inguinal hernia. The previous week, the referring veterinarian performed a prepurchase examination for intended use as an endurance horse. During right hind limb flexion for the lameness portion of the examination, the right hemiscrotum was noticed to be enlarged. On scrotal palpation, ingesta was felt, and it was concluded that an approximately 5-cm-diameter loop of intestine was in the scrotum. The hernia was manually reduced by external manipulation, and referral for laparoscopic surgical repair was recommended to the owner.
Physical examination of the horse at the referral hospital, performed 48 hours after the manual hernia reduction, revealed a 1.5-cm hydrocele (vaginocele) of the right hemiscrotum and normal results of palpation of the left hemiscrotum. Bilateral external palpation of the inguinal rings accommodated insertion of 4 fingers. The owner reported that the horse was castrated as a yearling and that up until the previous week, no abnormality of the scrotum had been noted. Transrectal palpation of the inguinal rings accommodated insertion of 3 fingers in the right side and 2 fingers in the left side. Other findings from the examination were considered normal. On the basis of results of the history and physical examination, a standing laparoscopy was scheduled for 3 days later.
In preparation for laparoscopy, the horse had free access to water but feed was restricted to 1 cup of soaked complete pelleted feeda with one-fourth cup of corn oil 4 times a day until there was a concaved contour to the paralumbar fossae (48 hours). Results of a CBC and serum biochemical analysis, rebreathing examination, and electrocardiography were within reference limits. Thirty minutes prior to starting the laparoscopic procedure, the horse was administered acepromazine (0.066 mg/kg [0.03 mg/lb], IM), penicillin G potassium (22,000 U/kg [10,000 U/lb], IV), gentamicin sulfate (6.6 mg/kg [3 mg/lb], IV), and flunixin meglumine (1.1 mg/kg [0.5 mg/lb], IV).
The horse was led into the standing operating room, restrained in stocks, and positioned for access to the paralumbar fossae. Detomidine hydrochloride (0.015 mg/kg [0.0068 mg/lb], IV) and butorphanol tartrate (0.025 mg/kg [0.011 mg/lb], IV) were then administered. Sedation was maintained with detomidine hydrochloride via continuous rate infusion (0.1 mg/kg/min [0.045 mg/lb/min], IV). The hair over the caudal aspect of the thorax, paralumbar fossae, and caudal flank was clipped, and the sites were prepared for surgery with chlorhexidine surgical scrub solution, alternating with sterile gauze soaked in saline (0.9% NaCl) solution by means of standard techniques. The rectum was manually evacuated, and a urinary catheter was aseptically placed for the duration of the operation.
After draping the surgical areas, 2% mepivacaine hydrochloride (20 to 40 mL) was infiltrated throughout the full-thickness body wall, focusing on the skin at each of 4 portal sites. On the left side, the first portal (laparoscope) was located at the level of the ventral tuber coxae between the last 2 ribs. The second portal (instruments) was located 5 cm below the dorsal margin of the internal abdominal oblique muscle midway between the last rib and tuber coxae. On the right side, the first portal was located just dorsal to the internal abdominal oblique muscle and just caudal to the last rib. The second portal was located 5 cm distal and caudal to the first portal. A 20-mm skin incision was made over the first portal location of the left side. A 5- to 12-mm adjustable portal sheath with conical obturator was placed into the abdominal cavity. The obturator was removed and replaced with a 50-cm-long, 10-mm-diameter, 30°-angle viewing laparoscope.b The abdomen was insufflated with CO2 (7 L/min) for 4 minutes and then turned off, which allowed clear viewing of the inguinal area and provided an intra-abdominal pressure of < 10 mm Hg. Once a field of view was established on the left side, the laparoscope was passed under the descending colon at the level of the bladder and then in a dorsocranial direction, providing a view of the right paralumbar area. A 15-mm skin incision was made over the first portal site, and a sheath and obturator were inserted, with the laparoscopic view used to confirm placement into the abdominal cavity. The second portal on the right was placed via the identical technique. The laparoscope was withdrawn from under the descending colon and focused on the intra-abdominal location for the second portal on the left side; it was again placed under laparoscopic guidance to confirm atraumatric entry into the abdominal cavity. After all 4 portal sheaths were established, the laparoscope was moved to the right side and focused on the right inguinal ring and an additional 25 L of carbon dioxide was insufflated on the right side. The appearance of the inguinal rings was consistent with the preoperative examination. The right vaginal ring was large, and the defect was compounded in that the vascular portion of the testicular pedicle was not located in the internal inguinal ring but suspended free in the abdomen.
To reduce the opening into the vaginal ring, a continuous suture pattern created with unidirectional barbed suturec was selected. The needle was removed from a 30-cm length of loop-ended 2-0 unidirectional barbed suture, and it was spliced by use of a square knot to a 6-cm strand of 2-0 braided lactomer suture and straight needle connected to the mechanical suturing instrumentd (Figure 1). The suture instrument was introduced into the abdomen, and the first bite was placed into the internal abdominal oblique muscle as far caudal as possible and just cranial to the testicular pedicle remnants (Figure 2). The next bite was of the adjacent body wall containing the external cremaster muscle and associated border of the vaginal ring. The needle was then placed through the loop at the end of the suture to allow fixation of the starting point of the suture line. Seven loops of the continuous pattern were placed, and the final pass was introduced in the reverse direction to secure the end of the suture line. The mechanical suturing instrument was removed from the abdomen, the laparoscopic scissors were then introduced in the instrument portal, and the suture tail was cut. The suture line required < 5 minutes to place by an experienced laparoscopic surgeon (Figure 3). The instruments were relocated to the left side, and the same sequence of barbed suture application was performed (Figure 4). At the conclusion of the laparoscopic procedure, the abdomen was deflated completely, 3 skin staples were placed on each of the 4 portal incisions, and the wounds were covered with an adhesive bandage.e The horse received penicillin G potassium (22,000 U/kg, IV, q 6 h), gentamicin sulfate (6.6 mg/kg, IV, q 24 h), and flunixin meglumine (1.1 mg/kg, IV, q 12 h) after surgery. The following morning, the horse had a mild fever of 38.7°C (101.6°F); thus, these 3 medications were continued until the temperature had been normal for 24 hours (by 48 hours after surgery). Transrectal palpation was performed the morning after the operation to sweep any bowel from the area of the internal inguinal rings in attempt to free any potential fibrin adhesions. A normal diet of grass hay, handwalking, and hand grazing were also started the day after surgery. All vital signs remained normal, and the horse was turned out to free-paddock housing after 7 days of stall housing.
Photograph of the mechanical suture instrument used for laparoscopic closure of the internal inguinal rings of a 4-year-old castrated Arabian horse demonstrating the single hand controls for passing the needle. Inset: close-up view of the working end of the mechanical suture instrument.
Citation: Journal of the American Veterinary Medical Association 242, 2; 10.2460/javma.242.2.249
Photograph of the placement of barbed suture in the caudal aspect of the right inguinal ring of a 4-year-old castrated Arabian horse.
Citation: Journal of the American Veterinary Medical Association 242, 2; 10.2460/javma.242.2.249
Photograph of the completed barbed suture line of the right inguinal ring of the horse in Figure 2.
Citation: Journal of the American Veterinary Medical Association 242, 2; 10.2460/javma.242.2.249
Photograph of the completed barbed suture line of the left inguinal ring of the horse in Figure 2.
Citation: Journal of the American Veterinary Medical Association 242, 2; 10.2460/javma.242.2.249
The horse remained clinically normal, and after 4 weeks, it returned to lunging and riding exercises; no rear limb lameness or abnormality of the scrotum was noted during or after exercise or rear limb flexion. At 6 weeks after surgery, the horse was reevaluated in our hospital and both internal inguinal rings were judged at 1-finger wide on palpation per rectum. At this time, a single-port laparoscopic evaluation of the inguinal rings revealed complete healing of the suture line and concurrent reduction of the ring size bilaterally (Figure 5). The horse continued to exercise for 20 months with no recurrence of the inguinal hernia.
Laparoscopic view at 6 weeks showing healed surgical site and continued hernia reduction of the right (A) and left (B) inguinal rings of the horse in Figure 2.
Citation: Journal of the American Veterinary Medical Association 242, 2; 10.2460/javma.242.2.249
Discussion
Inguinal herniation and rupture occur almost exclusively in stallions, but they have been reported in geldings1,2 and also a mare.3 In geldings, recurrent filling and fluctuation in the size of the scrotum have also been reported following primary skin closure castrations.4 Various methods for closure of the inguinal rings have been described. Closure of the superficial inguinal ring has been the traditional method for some years.2,5 This method, however, has the potential for recurrence,2 owing to the inguinal canal anatomy, and is also difficult to perform if a testicle is to be salvaged because of the need to ensure adequate blood supply to the spermatic cord.6 For these reasons, the focus has shifted to closure of the internal inguinal ring. Several laparoscopic inguinal herniorrhaphy techniques have been described since the description of transabdominal preperitoneal mesh repair in the horse under general anesthesia in a Trendelenburg's position.7 Different modifcations described elsewhere have evolved that include use of a laparoscopic stapling instrument,8 a standing laparoscopic technique performed with a cylindrical polypropylene mesh prosthesis,9 an intracorporeal suture closure,4 and use of a peritoneal flap transposition in a recumbent10 and standing horse.f
All herniorrhaphy or hernioplasty techniques have their potential advantages and disadvantages when compared with other techniques. The inherent risks of general anesthesia in the horse and further complications of the Trendelenburg's position are eliminated if the procedure is performed standing. With the horse in a standing position, however, use of the triangulation technique is more complex because of the anatomy, and there is less flexibility to transition the patient to a laparotomy if necessary. Although closure with a peritoneal flap transposition has the potential advantage of covering the ring and reinforcing the tissues, the dissection may predispose to postoperative adhesion formation with surrounding tissues.10 Techniques for operating on sexually intact stallions are more challenging than for geldings in that the herniorrhaphy in a stallion must not impinge upon circulation to the testicle or affect the function of the cremaster muscle or thermoregulation of the testicles, which would affect spermatogenesis.6 However, this consideration was not the main goal of this report.
Barbed suture has not been described previously to reduce the size of the internal inguinal rings in the horse. An early experimental study11 made the original claim that this type of suture minimizes tissue damage, leading to a milder foreign body reaction. An absorbable suture made of polydioxanone was developed and patented on the basis of the original design.12 The initial claims were that the knotless design may reduce scar tissue because of the absence of a notable foreign body reaction caused by knots. The barbed configuration anchors would also provide adequate tissue adhesion while the wound heals under minimum residual tension and pressure. The advantages of using barbed suture are the ease of placement, the fact that it maintains tissue apposition during suturing, and the fact that there is no need for knots that would potentially increase surgery time and tissue reaction from added suture material.
Currently, there 2 major different types of barbed suture: bidirectionalg and unidirectional.c In the bidirectional suture, the barbs change direction at the midpoint of the material and each end has a separate needle. In contrast, in the unidirectional design, all of the barbs are facing the same direction, there is a single needle, and the end of the suture contains a loop in which the suture will be passed after the first bite to anchor on itself. Both types do not require any knot tying. The 2 suture types also have a different barb design with regard to geometry, number, and helicity. A recent studyh compared the 2 suture types with conventional monofilament sutures as the control in pigs. There was no difference seen in biomechanical strength between the 2 sutures, and they were comparable with the traditional monofilament suture. Differences were also noted, with the bidirectional suturing technique requiring both forehand and backhand suturing, whereas the unidirectional did not. No dehiscence was observed in any of the barbed sutures, but there was a 4.2% rate of dehiscence for the traditional monofilament suture closure.h
In our opinion and clinical experience, the unidirectional suture is easier to use during laparoscopic application, especially with a minimal number of portals in a standing horse. The absorbable wound closure devicec is made from a copolymer of glycolic acid and trimethylene carbonate. The manufacturer claims that the device strength reduces to 80% by 7 days after surgery and to 65% by 3 weeks after surgery. Absorption is minimal until 60 days after surgery and is substantially complete within 6 months.i A major effort in suture design was to optimize the fabrication of the suture with specific barb spiral geometry.j The barbed suture has comparable wound holding strength to a conventional suture of 1 size smaller.h The commercial design of the barbed suture has a needle designed for optimal holding, which is smaller than the overall diameter of the suture with the barbs.
Potential consideration regarding the use of the barbed suture includes the price difference from conventional suture. Additionally, if a bite is misplaced, it cannot be pulled back without completely removing and starting the closure again. There is reported extrusion when the suture is placed too close to the dermis13 and migration following breakage.14 In theory, the possibility exists for increased infection because of the structure of the barbs allowing bacterial growth; however, the reported infection rate to date in human patients is 0.05%, which is similar to the rate of surgical site infection reported with conventional suture.13
The design and use of the mechanical suture instrumentd have been described.15 The tissue compression is confined to a maximum of 5 mm with the conventional design. We modified this by removing the needle from the barbed suture and attaching it to the needle of the mechanical suture instrument Although we have not mechanically tested this technique modification, it seems that there is a possibility of decreasing suture material as well as improving tissue apposition with the addition of the barbed suture. We believe that the combination of the 2 devices can provide a single technically efficient device with optimal tissue apposition and healing for inguinal hernioplasty. A recent report16 described the use of a novel design of barbed suture instrument, similar to the one we modified, for laparoscopic single-layer enterotomy closure in 24 dogs with very promising results. Closure of the inguinal ring in the standing horse can be very challenging because of the portal locations relative to the vaginal ring and the number of simultaneous instruments required for traditional suturing. The anatomy of the horse dictates a paralumbar approach with both instruments, with the endoscope directed in at an awkward angle toward the vaginal ring. This may cause the potential for frustration for not only the novice but also for experienced surgeons. With the use of a single instrument for suturing, the technique we describe eliminates the use of a second portal and makes the working space more accessible, makes the closure easier to perform, and, with the addition of the barbed suture, also adds security and persistent tissue apposition during the suture application.
Another major advantage of this technique is the lack of knot tying. Performing intracorporeal knot tying is a technical challenge that requires specialized skills. Laparoscopic suturing can be further compromised with a less-than-optimal angle of approach relative to the instrument portal and the site of suture application, especially in the standing horse. A comparison of a knotless self-anchoring suture material for urinary tract reconstruction in pigs was made with a standard laparoscopically tied suture.17 There were no differences in the 2 techniques in regard to the loads equivalent to tissue approximation. Also, a randomized controlled trial compared unidirectional barbed suture versus continuous suture with intracorporeal knots during performance of laparoscopic myomectomy18 It was concluded that the barbed suture reduces the time to suture the uterine wall, decreases intraoperative blood loss, and lowers the degree of difficulty of the procedure.
A potential disadvantage of this instrument used for the current procedure is its working length. The 37.5-cm working length that is currently available may not be sufficient when working with a larger-than-average horse or with very deep inguinal anatomy. Although we did not experience any major difference with the addition of the square knot between the 2 sutures, it may be argued that there is increased tissue drag and potential for knot failure. Hopefully, a commercial device will be available in the future to abolish this concern.
Inguinal herniorrhaphy with a knotless unidirectional barbed suture with the addition of a mechanical suture instrument in the 2-portal technique used in the present report was both simple and effective in closure of the internal inguinal ring in this horse. There are limitless potential uses of the barbed suture in veterinary surgery. Future use of barbed sutures in veterinary patients should help refine indications for use and provide guidelines for optimization.
Equine Senior, Purina Mills, St Louis, Mo.
Karl Stortz Endoscopy-America, Culver City, Calif.
V-Loc absorbable wound closure device, Covidien, Mansfield, Mass.
Polysorb Endo Stitch Auto Suture, Covidien, Mansfield, Mass.
Elasticon, Johnson & Johnson Inc, New Brunswick, NJ.
Wilderjans H, Simon O, Boussauw B. Standing laparoscopic approach in the horse for internal inguinal ring reduction using a peritoneal flap (abstr), in Proceedings. 11th World Equine Vet Assoc Cong 2009;443.
Quill Monoderm, Angiotech, Reading, Pa
Leung JC, Ruff GL, Batchelor SD. Performance enhancement of a knotless suture via barb geometry modifications (abstr), in Proceedings. 7th World Biomaterials Cong 2004;1587.
V-Loc wound closure devices for use in general surgery [pamphlet], New Haven, Conn: Covidien, 2011.
Godeheaver GT, Pineros-Fernandez A, Salopek LS, et al. Barbed sutures for wound closure: in vivo wound security, tissue compatibility and cosmesis measurements (abstr), in Proceedings. 30th Annu Meet Soc Biomaterials 2005;232.
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