Effect of omentectomy on adhesion formation in horses

Use of polyamide cable ties during experimental omentectomy in adult horses with histopathological assessment

OBJECTIVE

To report the use of nylon cable ties (NCT) for omentectomy in the horse.

STUDY DESIGN

Experimental study.

ANIMALS

Eight healthy adult horses.

METHODS

Horses underwent nylon cable tie (NCT) ligation of the greater omentum after ventral midline celiotomy. The time required to complete the omentectomy was recorded. Horses were recovered for 14 days before repeat celiotomy, adhesions assessment, and histological examination of the omentectomy site using a proposed histologic grading scheme. The total time for omentectomy procedure and histologic score was assessed for normality. Data are expressed as mean ± standard deviation.

RESULTS

NCT ligation provided sufficient hemostasis to complete the omentectomy (28 ± 15 s), without rescue ligation. No gross evidence of intra-abdominal adhesion or morbidity was associated with the omentectomy site 14 days after surgery. NCT were intact at the site of application, covered with smooth fibrous connective tissue. Adiponecrosis with minimal inflammation and fibrovascular occlusion of omental vessels was present at the surgical site. Mild inflammation was present at the NCT-tissue interface.

CONCLUSION

The use of NCT resulted in fast and effective omentectomy in healthy horses without short-term evidence of inflammatory reaction or intra-abdominal adhesion.

CLINICAL SIGNIFICANCE

The described technique provides an alternative for omentectomy in healthy adult horses.

Effects of hyaluronate-carboxymethylcellulose membranes on the clinical outcome of horses undergoing emergency exploratory celiotomy

OBJECTIVE

To determine the influence of hyaluronate-carboxymethylcellulose (HA-CMC) membranes applied to intestinal anastomoses or enterotomies on postoperative complications after emergency exploratory celiotomy.

STUDY DESIGN

Multicenter retrospective case-controlled series.

ANIMALS

Adult horses (59 in the HA-CMC group and 91 controls).

METHODS

Medical records from 4 referral hospitals were searched for horses ≥1 year of age, treated between 2008 and 2014 with emergency exploratory celiotomy, and surviving at least 24 hours postoperatively. Horses receiving repeat celiotomy during the same hospitalization were excluded. Horses who received HA-CMC were matched with controls who did not receive HA-CMC but had similar intestinal lesions and procedures at the same referral hospital. Postoperative complications (colic, nasogastric reflux, fever, incisional infection, and septic peritonitis), duration of hospitalization, and survival were compared between groups. Data were compared between horses by t test, Wilcoxon signed rank test, and χ² test.

RESULTS

The volume of nasogastric reflux at admission (P = .02) and the duration of administration of lidocaine after surgery (P = .02) were greater in horses with HA-CMC membranes than in controls. No difference in postoperative complications or survival was detected between groups: 48 of 59 (81%) horses treated with HA-CMC survived until discharge from the hospital compared with 80 of 91 (88%) horses in the control group (P = .27). Fifteen of 21 horses treated with HA-CMC and 30 of 43 horses in the control group survived >12 months after hospital discharge.

CONCLUSION

Application of HA-CMC membranes to anastomoses or intestinal incisions did not influence postoperative complications or survival after emergency celiotomy compared with controls.

CLINICAL SIGNIFICANCE

The safety and efficacy of HA-CMC membrane application to intestinal sites during colic surgery in horses is equivocal.

Prevention of post operative complications following surgical treatment of equine colic: Current evidence

Changes in management of the surgical colic patient over the last 30 years have resulted in considerable improvement in post operative survival rates. However, post operative complications remain common and these impact negatively on horse welfare, probability of survival, return to previous use and the costs of treatment. Multiple studies have investigated risk factors for post operative complications following surgical management of colic and interventions that might be effective in reducing the likelihood of these occurring. The findings from these studies are frequently contradictory and the evidence for many interventions is lacking or inconclusive. This review discusses the current available evidence and identifies areas where further studies are necessary and factors that should be taken into consideration in study design.

Peritoneal response to abdominal surgery: the role of equine abdominal adhesions and current prophylactic strategies

Intra-abdominal adhesions constitute a significant clinical and surgical problem that can lead to complications such as pain and bowel occlusion or subocclusion. These adhesions are frustrating and potentially fatal, representing a major postoperative complication in abdominal surgery. It is estimated that 32% of horses undergoing laparotomy will present clinical symptoms due to adhesions, but the true prevalence is not known because a large proportion of animals with postoperative recurrent colics are medically treated or submitted to euthanasia without necropsy. Adhesions are highly cellular, vascularized, dynamic structures that are influenced by complex signaling mechanisms. Understanding their pathogenesis could assist in applying better therapeutic strategies and in developing more effective antiadhesion products. Currently, there are no definitive strategies that prevent adhesion formation, and it is difficult to interpret the results of existing studies due to nonstandardization of an induction model and evaluation of their severity. The best clinical results have been obtained from using minimally traumatic surgical techniques, anti-inflammatory agents, antimicrobials, anticoagulants, and mechanical separation of serosal surfaces by viscous intraperitoneal solutions or physical barriers. This paper aims to review adhesion formation pathogenesis, guide the understanding of major products and drugs used to inhibit adhesion formation, and address their effectiveness in the equine species.

Barium peritonitis in small animals

Barium peritonitis is extremely rare, but is difficult to treat and may be life-threatening. Barium suspension leakage from the gastrointestinal tract into the abdominal cavity has a time-dependent and synergistically deleterious effect in patients who have generalized bacterial peritonitis. The severity of barium peritonitis is dependent on the quantity of barium in the abdominal cavity. Barium sulfate leakage results in hypovolemia and hypoproteinemia by worsening the exudation of extracellular fluid and albumin. Abdominal fluid analysis is a useful and efficient method to diagnose barium peritonitis. Serial radiographs may not be a reliable or timely diagnostic technique. Initial aggressive fluid resuscitation and empirical broad-spectrum antibiotic treatment should be instituted promptly, followed quickly by celiotomy. During exploratory surgical intervention, copious irrigation and direct wiping with gauze are employed to remove as much barium as possible. Omentectomy should be considered when needed to expedite barium removal. Despite aggressive medical and surgical treatments, postoperative prognosis is guarded to poor due to complications, such as acute vascular shock, sepsis, diffuse peritonitis, hypoproteninemia, electrolyte imbalance, cardiac arrest, small bowel obstruction related to progression of granulomas and adhesions in the abdominal cavity. Therefore, intensive postoperative monitoring and prompt intervention are necessary to maximize chances for a positive outcome. For those that do survive, small bowel obstruction is a potential consequence due to progression of abdominal adhesions.

Adhesions after laparoscopic and open ileal pouch-anal anastomosis surgery for ulcerative colitis

BACKGROUND

Emerging evidence suggests that a laparoscopic approach to colorectal procedures generates fewer adhesions. Even though laparoscopic ileal pouch-anal anastomosis (IPAA) is a lengthy procedure, the prospect of fewer adhesions may justify this approach. The aim of this study was to assess abdominal and adnexal adhesion formation following laparoscopic versus open IPAA in patients with ulcerative colitis.

METHODS

A diagnostic laparoscopy was performed at time of ileostomy closure. All abdominal quadrants and the pelvis were video recorded systematically and graded offline. The incisional adhesion score (IAS; range 0-6) and total abdominal adhesion score (TAS; range 0-10) were calculated, based on the grade and extent of adhesions. Adnexal adhesions were classified by the American Fertility Society (AFS) adhesion score.

RESULTS

A total of 43 patients consented to participate, of whom 40 could be included in the study (laparoscopic 28, open 12). Median age was 38 (range 20-61) years. There was no difference in age, sex, body mass index, American Society of Anesthesiologists grade and time to ileostomy closure between groups. The IAS was significantly lower after laparoscopic IPAA than following an open procedure: median (range) 0 (0-5) versus 4 (2-6) respectively (P = 0·004). The TAS was also significantly lower in the laparoscopic group: 2 (0-6) versus 8 (2-10) (P = 0·002). Applying the AFS score, women undergoing laparoscopic IPAA had a significantly lower mean(s.d.) prognostic classification score than those in the open group: 5·2(3·7) versus 20·0(5·6) (P = 0·023).

CONCLUSION

Laparoscopic IPAA was associated with significantly fewer incisional, abdominal and adnexal adhesions in comparison with open IPAA.

Peritoneal adhesions in human and veterinary medicine: from pathogenesis to therapy. A review

Any peritoneal inflammatory process consequent to infections or surgical injuries may induce abdominal adhesion formation. Peritoneal adhesions are connective laciniae that develop among abdomino-pelvic organs that limit physiologic visceral motion. Consequently, fertility may be impaired, and intestinal obstruction and pelvic pain may develop, mainly in subjects that had undergone gynaecological surgery. This review illustrates the pathogenic steps of adhesiogenesis and the therapeutic scenario that evolved over the years to tackle the threat of peritoneal adhesions, both in domestic animals and in women.

Update on recent advances in equine abdominal surgery

In recent years important advancements in colic surgery have led to improved prediction of survival rates, better survival rates, and decreased complication rates. This article describes several modalities to combat and prevent incisional hernia and intestinal adhesion formation in horses undergoing colic surgery. These modalities have had a positive impact on reducing complications in horses after surgery.

Primary Omental Abscessation or Omental Infarction in Four Dogs

Primary omental abscessation was diagnosed in three dogs after laparotomy. Laparotomy was performed to explore an abdominal mass of unknown origin and chronic fat necrosis diagnosed in one dog as an incidental finding during ovariohysterectomy. Primarily hypoechoic masses not connected to any abdominal structures were visualized with abdominal ultrasound in three dogs. Suppurative inflammation was diagnosed from fine-needle aspirate evaluation in two dogs. Bacteria were cultured from two abscesses despite the absence of organisms on Gram stain, cytology, and histopathology. Foreign material was found in one abscess. All four dogs experienced weight loss and/or an episode of gastrointestinal signs. Primary omental abscessation may be preceded by omental vascular compromise and/or interaction of the omentum with foreign material.

Survival and complication rates in 300 horses undergoing surgical treatment of colic. Part 3: Long-term complications and survival

REASONS FOR PERFORMING STUDY

Few studies have evaluated long-term survival and complication rates in horses following surgical treatment of colic, making it difficult to offer realistic advice concerning long-term prognosis.

OBJECTIVE

To review the complications occurring after discharge from hospital and survival to >12 months after surgery of 300 horses undergoing exploratory laparotomy for acute colic. Pre-, intra- and post operative factors that affected long-term complications and long-term survival were assessed.

METHODS

History, clinical findings, surgical findings and procedures and post operative treatments of 300 consecutive surgical colic cases (1994-2001) were reviewed. Long-term follow-up information was retrieved from case records and telephone enquiries from owners.

RESULTS

The long-term (>12 months) survival rate for 204 horses discharged after colic surgery and for which follow-up information was available was 84%. The most common complication after discharge was colic, affecting 35.1% of horses following a single laparotomy. Colic was most common in horses that had had small intestinal obstructions, bowel resection or post operative ileus. Abdominal adhesions were most common in horses that presented with severe colic due to strangulation of small intestine. Ventral hernia formation occurred in 8% of horses, and was most common in horses that had had post operative wound drainage or infection.

CONCLUSIONS

This study identified various factors that appear to predispose horses to long-term complications after colic surgery.

POTENTIAL RELEVANCE

Further evaluation of strategies that might reduce the incidence of such complications are needed; in particular, the value of intraperitoneal heparin should be evaluated, and procedures designed to reduce the rates of wound drainage and infection assessed.

Recent advances in equine abdominal surgery

Laparoscopy is a minimally invasive procedure that has applications as a diagnostic, therapeutic and prognostic technique. Specialized equipment is necessary to perform equine laparoscopy, and there is a large range of instruments, both disposable and non-disposable available. Laparoscopic procedures described include ovariectomy, cryptorchidectomy, adhesiolysis and herniorrhaphy. Laparoscopy can be performed in a standing or dorsally recumbent position, depending on surgeon preference, patient status and the procedure to be performed. Stapling equipment is frequently used in gastrointestinal surgery in horses. Advantages include decreased surgical time and a decrease in the risk of contamination. Stapling equipment is often used in creating anastomoses, both in the large and small intestines, as well as in vessel ligation. New surgical techniques intended to decrease adhesion formation include the use of carboxymethylcellulose and bioresorbable patches. Indwelling abdominal drains can be used for peritoneal lavage following surgery and also appear to decrease the risk of adhesion formation. Improvements in post-operative care, including the treatment of post-operative ileus and endotoxaemia can significantly improve the outcome of horses that have undergone surgery for abdominal disorders. Recommendations for the use of prokinetic agents in horses with ileus vary widely. Prokinetic agents include local anaesthetics, macrolide antimicrobials, cholinergic agonists and dopamine antagonists. Endotoxaemia is common in horses following surgery for gastrointestinal disorders. The antibiotic polymyxin B binds to the circulating endotoxin molecule, decreasing its half-life in the intra-vascular space and reducing associated inflammation. This drug appears to be an effective and affordable treatment option for horses with endotoxaemia. The use of specific cyclooxygenase inhibitors in veterinary medicine have been studied recently. Selective cyclooxygenase-2 inhibitors may provide comparable anti-inflammatory and analgesic properties to the non-selective non-steroidal anti-inflammatory drugs. These drugs appear to have similar clinical effectiveness and will hopefully minimize deleterious side effects. The optimal healing of ventral midline incisions in horses is related to many factors including appropriate suture patterns and bite size, in addition to appropriate post-operative exercise recommendations. Recent advances in surgical techniques and post-operative care should decrease the morbidity and mortality associated with abdominal surgery. This article provides an overview of some of these advances.

Abdominal Surgery in Neonatal Foals

Abdominal surgery in foals under 30 days old has become more common with improved neonatal care. Early recognition of a foal at risk and better nursing care have increased the survival rates of foals that require neonatal care. The success of improved neonatal care also has increased the need for accurate diagnosis and treatment of gastrointestinal, umbilical, and bladder disorders in these foals. This chapter focuses on the early and accurate diagnosis of specific disorders that require abdominal exploratory surgery and the specific treatment considerations and prognosis for these disorders.

Effect of carboxymethylcellulose and hyaluronate solutions on jejunal healing in horses

OBJECTIVE

To compare a double-layer inverting anastomosis with a single-layer appositional anastomosis, coated with either 1% sodium carboxymethylcellulose (SCMC) or 0.4% sodium hyaluronate (HA) solutions, in the small intestine of horses with respect to anastomotic healing and adhesion formation.

ANIMALS

18 adult horses.

PROCEDURE

Midline celiotomy and end-to-end jejunal anastomoses were performed. In control group horses (n = 6), a double-layer inverting anastomosis coated with sterile lactated Ringer's solution was performed. In treatment group horses, a single-layer appositional anastomosis was performed that was coated with 1% carboxymethylcellulose solution (SAA + SCMC group horses, 6) or 0.4% hyaluronate solution (SAA + HA group horses, 6). An additional 500 mL of the respective treatment solution was applied to the jejunal serosal surface, and 2 jejunal serosal abrasion sites were created. Horses were euthanatized 10 days after surgery. Anastomoses and abdominal adhesions were evaluated grossly. Anastomotic healing was evaluated on the basis of bursting wall tension.

RESULTS

Bursting wall tension was significantly greater in SAA + SCMC group horses, compared with control group horses. All intestinal segments failed at a point distant to the anastomosis. Significantly fewer adhesions were found at the abrasion sites of SAA + HA group horses, compared with control group horses. No differences were found in adhesion formation at the anastomotic sites among groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Coating a single-layer appositional jejunal anastomosis with SCMC or HA solutions does not adversely affect anastomotic healing. Application of 0.4% HA solution to the serosal surface of the jejunum significantly decreases the incidence of experimentally induced intra-abdominal adhesion formation in horses.

Prevention and treatment of gastrointestinal adhesions

As with many aspects of clinical medicine, there is yet to be a single or definitive cure for postoperative adhesion formation. Current methods of prevention target risk factors predisposing horses to adhesion formation. Systemic pharmacologic therapies, such as antimicrobials, nonsteroidal anti-inflammatory drugs, Salmonella antiserum, and hyperimmune plasma, help to reduce abdominal inflammation and minimize the effects of endotoxemia. Intra-abdominal or systemic heparin aids in enhancing peritoneal fibrinolysis. Prokinetic therapy promotes early postoperative return of intestinal motility, minimizing the propensity for adhesion formation between apposing adynamic segments of intestine. Mechanical separation of potentially adhesiogenic serosal and peritoneal surfaces is commonly achieved with use of abdominal lavage, protective coating solutions, and barrier membranes. Ongoing and future research is directed toward a better understanding of the local effects of intestinal trauma and the corresponding response of the fibrinolytic system. Recognition of horses at high risk for adhesion formation helps to guide the equine surgeon to an appropriate perioperative and intraoperative plan for adhesion prevention, including good surgical technique and a combination of adjunct therapies.

Evaluation of laparoscopic adhesiolysis for the treatment of experimentally induced adhesions in pony foals

OBJECTIVE

To assess the efficacy of laparoscopic adhesiolysis in the treatment of experimentally induced adhesions in foals.

ANIMALS

8 healthy pony foals.

PROCEDURE

Celiotomy was performed and adhesions created at the jejunoileal junction and at sites 0.5 and 1 m proximal to this junction, using a serosal abrasion method. Ten days after celiotomy, exploratory laparoscopy was performed. Laparoscopic adhesiolysis was performed in the treatment group only (4 foals, randomly selected). Thirty days after the exploratory laparoscopy, a final laparoscopic examination was performed, and the foals were euthanatized. The number and characteristics of abdominal adhesions were recorded during laparoscopy 10 and 30 days after celiotomy and during necropsy.

RESULTS

At 30 days after celiotomy, the number of adhesions in the control group was significantly higher than the number in the treatment group. In the control group, all adhesions observed during the exploratory laparoscopy were still evident at the final laparoscopy and necropsy. In the treatment group, adhesions did not form again after separation. During final laparoscopy and necropsy, a focal adhesion between the omentum and site of the initial laparoscope portal was observed in 5 of 8 foals.

CONCLUSIONS AND CLINICAL RELEVANCE

The serosal abrasion model is useful for studying abdominal adhesions in foals. Laparoscopic adhesiolysis was an effective technique to break down experimentally induced adhesions in the early maturation stage of formation in pony foals. Studies are required to investigate prevention of de novo adhesions at the laparoscope portal sites.

Use of a hyaluronate membrane for jejunal anastomosis in horses

OBJECTIVE

To compare the outcomes of double-layer inverting anastomosis (DIA), single-layer anastomosis (SLA), and single-layer anastomosis combined with a hyaluronate membrane (SLA+HA-membrane) with respect to stomal diameter, adhesion formation, surgery time, and anastomotic healing in horses.

ANIMALS

18 adult horses.

PROCEDURE

Midline celiotomy and end-to-end anastomoses were performed. In control horses (n = 6), DIA was performed; in treated horses, SLA was performed (6) or SLA+HA-membrane was performed (6). Horses were euthanatized 21 days after surgery. Abdominal adhesions were evaluated grossly and histologically. Stomal diameters were measured ultrasonographically and compared with adjacent luminal diameters. Anastomotic healing was evaluated histologically for fibrosis and inflammation, tissue alignment, and inversion. Surgery times were recorded for the anastomotic procedure and compared among groups.

RESULTS

There were significantly more adhesions in the SLA group, compared with the DIA and SLA+HA-membrane groups. Reduction in stomal diameters in the DIA group was significantly greater than the SLA and SLA+HA-membrane groups. Surgery times for the DIA group were significantly greater than the SLA and SLA+HA-membrane groups. Histologic findings of fibrosis, inflammation, and mucosal healing were similar among groups. There was significant tissue inversion in the DIA group, compared with the 2 treatment groups. Tissue alignment was not different among groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of a SLA+HA-membrane was an effective small intestinal anastomotic technique. This technique was faster to perform and resulted in a larger stomal diameter, compared with the DIA technique and significantly fewer perianastomotic adhesions, compared with the SLA technique.

Colic surgery in 206 juvenile thoroughbreds: survival and racing results

The purpose of our study was to determine the types of lesions that cause colic in juvenile Thoroughbreds, factors associated with these lesions and the subsequent survival and athletic performance of the juveniles. The age of juvenile Thoroughbreds requiring surgical exploration for abdominal pain has an influence on the type of lesion causing colic. The short-term survival rate (discharge from the hospital) after colic surgery for foals was 85% and was strongly influenced by the lesion causing colic. Thirteen percent of juveniles recovered from the first surgery experienced another severe colic episode requiring additional surgery or euthanasia. Eight percent of foals recovered from the first celiotomy developed adhesions. Adhesion formation was related to the initial lesion causing colic and the foals' age at the first surgery. Foals being suckled (15 days to 6 months) were at greatest risk for adhesions and more frequently required multiple surgeries. Juvenile Thoroughbreds that had a celiotomy were significantly less able to race (63%) than their unaffected siblings (82%), and age at the initial surgery was associated with the percentage of horses that raced. However, affected foals able to race won as much money, raced as often, and made as many starts as their siblings. Colic and surgical treatment have a negative impact on athletic performance, but the majority of foals discharged from the hospital after colic surgery will perform athletically as adults.

Effect of carboxymethylcellulose and a hyaluronate-carboxymethylcellulose membrane on healing of intestinal anastomoses in horses

OBJECTIVE

To evaluate the effect of sodium carboxymethylcellulose (SCMC) or a hyaluronate-carboxymethylcellulose membrane (HA membrane) on healing of the small intestine in horses.

ANIMALS

18 healthy adult horses.

PROCEDURE

Midline celiotomy and 2 jejunal resection-and-anastomosis surgeries were performed. In treated horses, SCMC (n = 6) or a HA membrane (6) was applied to the jejunum to cover the anastomosis. There were 6 untreated control horses. Horses were euthanatized 10 days after surgery. For each horse, 1 anastomosis was used for histologic examination, and the second was used to determine intestinal bursting strength. Intestinal bursting tension, serosal granulation tissue, serosal fibrin deposition, and width of the fibrous seal at the anastomosis were compared among groups.

RESULTS

3 control horses had adhesions associated with the anastomosis, but none of the treated horses had adhesions associated with the anastomosis. Mean thickness of fibrin deposited on the serosal surfaces for the SCMC and HA-membrane groups was significantly less than that for control horses. Mean thickness of serosal granulation tissue, width of fibrous seal between inverted musculature, inflammatory cell infiltrate scores, and bursting tension did not differ significantly among groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of SCMC or application of a HA membrane to small intestinal anastomoses in horses resulted in fewer adhesions and decreased fibrin deposition, and it did not adversely affect anastomotic healing. In horses at increased risk for intra-abdominal adhesions, SCMC or application of HA membranes may decrease the frequency of adhesions without adversely affecting healing of small intestinal anastomoses.

Evaluation of a bioresorbable hyaluronate-carboxymethylcellulose membrane for prevention of experimentally induced abdominal adhesions in horses

OBJECTIVE

To evaluate the efficacy of a bioresorbable hyaluronate-carboxymethylcellulose membrane (HA-membrane) for prevention of experimentally induced abdominal adhesions in horses.

STUDY DESIGN

Experimental study.

ANIMAL POPULATION

Twelve healthy adult horses.

METHODS

The effect of an HA-membrane on adhesion formation was evaluated in 12 healthy horses using an established model of serosal trauma to induce adhesions. A ventral median celiotomy and two jejunal resections and end-to-end anastomoses were performed. Two separate jejunal areas were abraded, and three 2-0 chromic gut sutures placed in the abraded areas. In treated horses (n = 6), HA-membranes were applied to the jejunum to completely cover the anastomoses and abraded areas of jejunum. Nontreated horses (n = 6) served as controls. All horses were killed 10 days after surgery. The abdominal cavity was evaluated for adhesion formation. The frequency of intra-abdominal adhesions between groups was compared with a chi2 test with statistical significance set at P < .05.

RESULTS

All control horses had intra-abdominal adhesions; fibrous adhesions were associated with both jejunal abrasion sites in 5 horses. One treated horse developed adhesions. There were significantly fewer adhesions in the HA-membrane-treated group (P < .0034).

CONCLUSIONS

In this experimental model, application of an HA-membrane to a localized area of serosal trauma reduced the frequency of intra-abdominal adhesion formation.

CLINICAL RELEVANCE

Application of an HA membrane may decrease the frequency of adhesions in horses at an increased risk of postoperative adhesion formation.