A Comparative Study of Conventional Suture and Stapler Anastomosis for Gastro-intestinal Surgery in Dogs

Background: Gastro-intestinal anastomosis is mostly performed to correct the gastro-intestinal surgical disorders like gastro-intestinal obstruction, abdominal trauma, perforated bowel, intussusception and intestinal neoplasia etc . In early periods conventional intestinal anastomosis was followed which evolved into a seromuscular pattern of suture technique in recent years. Stapled anastomosis have a higher tensile strength than sutured anastomosis, since they heal by primary intention with minimal inflammation. Taking above facts into consideration, this study was undertaken to compare the conventional suture with stapler anastomosis of gastro-intestinal surgery in dogs. Methods: Clinical cases of dogs which were reported to Small Animal Out-Patient (Surgery Unit) of Madras Veterinary Teaching Hospital, Chennai, with the symptoms of gastro-intestinal obstruction due to multifactorial causes formed the study material that were randomly divided into two groups of 6 dogs each. Group I Cases were treated with conventional suture, Group II were treated with gastrointestional anastomosis staplers. Plain and contrast radiography, ultrasonography, intestional anastomosis time, resumption of oral feeding, matrix metalloproteinase were performed. Result: Stapler technique was found to be superior, accurate and most effective than the conventional technique in terms of anastomotic constructing time, less bowel manipulation, tissue trauma, anaesthetic exposure, risk of peritoneal contamination, early resumption of gastro-intestinal motility and oral feeding, rapid healing at the anastomotic site and reduced hospital stay. Moreover the procedure was easy to perform and simple.


INTRODUCTION
Gastro-intestinal anastomosis is mostly performed to correct the gastro-intestinal surgical disorders like gastro-intestinal obstruction, abdominal trauma, perforated bowel, intussusception and intestinal neoplasia etc. Perforated gastro-intestinal tract, Chronic Inflammatory Bowel Disease and colonic cancer are the major indications for gastrointestinal resection and anastomosis (Johnson et al. 2007). Conventional intestinal anastomosis dates back to 1000 B.C. the era of Sushruta, followed by Lembert 1826, who introduced the seromuscular pattern of suture technique. In recent years, most of the surgical gastro-intestinal anastomosis in human are performed with staplers. Stapled anastomosis have a higher tensile strength than the sutured anastomosis, since they heal by primary intention with minimal inflammation. In addition to the above, this type of anastomosis creates a larger intestinal luminal stoma when compared to the original (Ballantyne et al.,1985). Conventional suture results in post-operative illeus due to over manipulation, delays oral intake, healing and comparatively increases the surgical duration (Braga et al., 2001 andVora et al., 2014). In comparison, Stapler technique takes less anastomotic construction time, minimal manipulation, haemorrhage, reduces risk of peritonitis and dehiscence. Taking above facts into consideration, this study was undertaken to compare the conventional suture with stapler anastomosis of gastro-intestinal surgery in dogs with following objectives.

MATERIALS AND METHODS
Clinical cases of dogs which were reported to Small Animal Out-Patient (Surgery Unit) of Madras Veterinary Teaching Hospital, Chennai, with the symptoms of gastro-intestinal obstruction due to multifactorial causes formed the study material from 2019-21. The inclusive criterias were gastro intestional obstruction due to foreign bodies, intussuception, gastrointestional tumors with exclusion of peritonitis induced due to G.I. rupture, gastric dilatation and volvulus. A written medical consent was obtained from the owners preoperatively. Twelve cases selected for the study were randomly divided into two groups of six dogs each. Group I cases were treated with conventional suture, Group II were treated with gastrointestional anastomosis-staplers. Routine pre and post operative hemato-biochemical profiles were performed.

Plain and contrast radiograph
Plain radiographs of lateral and dorsoventral view of the abdomen were taken pre-operatively to rule out gastrointestinal foreign bodies and post-operatively on 5 th day to asses anastomotic leakage in all the cases. Any ground glass appearance in the abdomen radiograph was classified as cases with peritonitis due to leakage from the intestional anastomosis. Contrast radiography was done with Barium sulphate at the dose rate of 10 ml/ kg body weight to diagnose radiolucent foreign bodies pre-operatively as described by Orsher and Rosin (1993) Chiang and Chou et al. (2005).

Ultrasonography
Ultrasonography was performed to diagnose the gastrointestinal foreign bodies, intussusception, tumour preoperatively and to assess gastro-intestinal motility postoperatively on 4 th day.
The time taken to perform intestinal anastomosis excluding the ligation of arcadian blood vessels were recorded for all cases. Post-operative convalescent time (duration from day of surgery to discharge) was recorded in both the groups for all cases. Resumption of oral feeding (hours) after surgery as reported by the owners in both groups.

Estimation of matrix metalloproteinase 13 (MMP 13)
Whole blood sample were collected post-operatively on (3 rd , 5 th and 7 th day) for assessment of anastomotic healing in group I and group II.

Conventional enterectomy and enteroanastomosis
Diseased or inflammed part of intestine was exteriorized and isolated from the abdomen. The intestinal contents (chime) were gently milked away from the inflamed part of the intestine. A non-crushing Doyens intestinal forceps was used to occlude the lumen of both the ends of the proposed enterectomy site. Intestinal viability was assessed by visualising the colour, peristaltic motility and arterial pulsation to determine the amount of intestine to be resected. Arcadian mesenteric vessels from the cranial mesenteric artery which supplied to the intestine were double ligated and transected using PGA 2-0. Terminal arcadian vessels and vasa recta vessels within the mesenteric fat at the place of the resected intestine was double ligated from the diseased bowel site. The diseased intestine was transected using scalpel (or) Metzenbaum scissors. A wide perpendicular (or) oblique incision at least 8cm in length was made on either sides for resection of intestinal tumour. Incised portion of the intestine was anastomosed using PGA 4-0 absorbable suture with swaged-on taper point needle. Intestinal anastomosis suture, started from the mesenteric border with single knot and another knot placed at the antimesentric border. Simple interrupted sutures were placed through all the layers of the intestinal wall not more than 2-3 mm apart. The knots were placed extraluminally (Fig 1, 2) in order to appose the edges of intestine as described by Nash (2006). The anastomotic site and the abdominal cavity was lavaged with one liter of warm NS and 1 00 ml of w arm metronidazole. R outine closu re of ventral midline coeliotomy incision was apposed with three layer closure.

Gastro-intestinal anastomosis using gastro intestinal anastomosis directional stapling (dst) technique linear cutter stapler
Gastro intestinal anastomosis (GIA) Directional Stapling Technique (DST) with linear cutter stapler.The GIA™ 60 stapler of 60 mm length which had reloadable titanium nonmagnetic staples placed in two double staggered rows was used in the present study (Mortenson and Ashraf 2008).

GIA-DST cartridge
A 3.8 mm size disposable cartridge was used in the present study for stapling (Fig 3).

Surgical technique
For all cases in group II, entero-anastomosis was performed using GIA Linear cutter stapling gun using disposable

A Comparative Study of Conventional Suture and Stapler Anastomosis for Gastro-intestinal Surgery in Dogs
relo ad ed stap ling un its (Mu ltifire 3 .8 m m G IA 6 0 Covedien). A fter the arcadian vessels was ligated, d iseased (o r) inflamm ed part o f the intestin e was transected. Each limb of the stapler was placed into each bowel (Fig 4); which created a stoma by dividing the anastomosed bowel between the two double staple lines. The stoma was examined for presence of haemorrhage (Fig 5). Stapled stoma was lifted for positioning the open lumen for next firing. The used staple cartridge from the gun was discarded and reloaded with a new cartridge. The forks of the stapler was positioned around the anastomosed bowel at 90 degree to its long axis and adjacent to its opening (Fig 6). The two limbs of the stapler were aligned and locked to ensure that the previously stapled edges of intestine were separated by atleast 1 cm (W hite 2008) (Fig 7). The anastomosis was completed after firing the stapler. The anastomosed staple line was examined fo r the eviden ce o f haem o rrhage (or) deployment (F) failure (Fig 8a, b). The anastomotic site and the abdominal cavity was lavaged with warm normal saline and 100 ml of warm Metronidazole. Routine closure of ventral midline coeliotomy incision was apposed with three layer closure.

RESULTS AND DISCUSSION
Among the 12 dogs in the clinical study the aetiology for gastro-intestinal obstructions were found to be linear foreign bodies (3), stone (3), intestinal tumour (2), intussusception (2), kernel (mango seed) (1) and megacolon (1). Among the 12 dogs which were operated during the study period, highest incidence of location of gastro-intestinal obstructions were observed in jejunum (33.33%) followed by ileocaecal (25.02%), duodenum (16.66%) and caecocolic, colon and stomach (8.33%). Plain radiograph was taken on 5 th day post-operatively, to ascertain peritonitis due to anastomotic leakage in all cases and to visualise stapler pins (Fig 9, 10). Intestinal leak with peritonitis was observed in 2 dogs in conventional suture group which was depicted with diffuse ground glass appearance with loss of serosal details. Whereas no leakage was noticed stapled group. Intestinal anastomotic leakage of clinical suspicion were significantly higher in conventional suture group than the stapler group as also reported by Docherty et al. (1995): George (1991); Kracht et al. (1993).
3 cases of radiolucent linear foreign body, 2 cases of intestinal tumours and 1 case of megacolon were diagnosed through contrast radiograph. Kracht et al. (1993); Moran

A Comparative Study of Conventional Suture and Stapler Anastomosis for Gastro-intestinal Surgery in Dogs
(1996) used contrast radiography and observed asymptomatic true radiological leakage in the stapled and sutured anastomotic patient (Table 1).
Ultrasound guided gastro-intestinal motility was observed 4 th post-operative day in all cases to rule out any leakage and post healing complications, if any. (Fig 11, 12). The Mean±SE for time taken for the return of gastro-intestinal motility in suture group was 4.67±0.61 days and 3.33±0.33 days in stapler group. A statistically significant decrease was observed in stapler group compared with the suture group. A highly significant decrease (p<0.05) in time taken for anastomosis in stapled group compared with suture group was observed which concurred with the findings of Vora et al. (2014) ; Bin-wei Liu et al. (2014) ; Thakor et al. (2014).
Stapled method reduced the operating time, surgical trauma, intra-operative blood loss, minimized bowel manipulation, risk of peritoneal contamination and anaesthetic cost in the present study which was similar to the findings of Azevedo et al. (2008). A highly significant decrease (p<0.05) in post-operative convalescent time for stapled method was observed when compared to suture method which concurred with the findings of Weijan and Jianrong (2006). There was highly significant decrease in the time taken for resumption of oral feeding in stapled method (p <0.05), which coincided with the findings of Damesha et al. (2008). Less manipulation of bowel, anastomotic time, surgical trauma, anesthetic exposure and risk of peritoneal contamination reduced the time taken for resumption of oral feeding in stapled method (Table 2) as also observed by Nichkaode et al., 2013. Antibiotic Sensitivity Test was performed on anastomotic leak fluid of 33% cases of group I which were found to be positive for peritonitis based on clinical symptoms and confirmation by abdominal radiograph. Cefotaxime and Gentamicin drugs were found sensitive and the same antibacterial were used for treatment at dose rate of 20 mg/Kg i.v and 4 mg / Kg i.m respectively for seven days post-operatively which were also opined to be effective by Papazoglou et al. (2001)         Vag h o lk ar (2 0 0 1 ) rep o rted th at th e M M P activity increased throughout the gastro-intestinal tract after transection and re-anastomosis by hand sewn suture method and Krarup et al. (2013) concluded that selective MMP inhibition enhanced anastomotic strength in colonic anastomotic site. Jiborn et al. (1978) studied experimentally the effect of suture technic on collagen concentration in the colonic wall and concluded that collagen concentration was temporarily decreased close to anastomotic site which correlated with the results in the present study. MMPs has an important role in the development, turnover and repair of different tissue Rawlings et al. (2012). During wound healing activation, MMPs was required for degradation of the provisional wound matrix thereby creating space for cell migration, angiogenesis and ECM remodelling. Since the stapler pins are made up of titanium which were non inflammatory, provided a high tensile strength and tissue holding capacity. It also reduced the trauma at the anastomotic site with less release of collagenase enzymes and resulted in less lytic action on the collagen (wound matrix) at the anastomotic site which led to reduction in rate of dehiscence and rate of leakage. Factors such as traumatic suturing, faecal contamination and infection all increased the amount of local collagenase produced at the wound and hence could increase the risk of infection.

CONCLUSION
The time taken for anastomosis in group I animal was significantly decreased when compared to suture group. A highly significant decreased post-operative convalescent time for stapled method was observed when compared to suture method.
Resumption of oral feeding for stapled method showed a statistically significant increase. An increase MMP activity was observed throughout the GI tract after resection and anastomosis by conventional suture method when compared to stapled method.
To conclude, stapler technique was found to be superior, accurate and most effective than the conventional technique in terms of anastomotic constructing time, less bowel manipulation, tissue trauma, anaesthetic exposure, risk of peritoneal contamination, early resumption of gastrointestinal motility and oral feeding, rapid healing at the anastomotic site and reduced hospital stay. Moreover the procedure was easy to perform and simple.
On the economy aspect the stapler was more expensive than the suturing as this technique compensates the cost by reducing anaesthetic cost and hospital stay.