Case Report

Parainguinal laparotomy as an alternative surgical approach forremoval of an enterolith in the small colon of a horseE. J. Barrett* and A. S. MunstermanDepartment of Clinical Sciences, JT Vaughan Large Animal Teaching Hospital, Auburn University, Alabama, USA.*Corresponding author email: ezb0021@auburn.edu

Keywords: horse; parainguinal approach; faecalith; small colon; enterotomy

SummaryThis report describes the use of a parainguinal approach to theabdomen to remove an obstruction in the small colon thatcould not be removed using an initial ventral midlineapproach. The use of a parainguinal approach should beconsidered for removal of an obstruction in the distal portion ofthe small colon.

IntroductionObstructive disorders of the small colon are diagnosedin 2–5% of all horses presenting to referral centres forabdominal pain (Edwards 1997; Pierce 2009; Plummer 2009).Depending on the geographic location, up to 35% of thesesmall colon obstructions are caused by enteroliths, comprisedof mineral deposition arranged around a central nidus. Othercauses of small colon obstructions include faecaliths, foreignbodies, pedunculated lipomas or bezoars (Schumacher andMair 2002; Pierce 2009). Most commonly, an enterolithbecomes lodged in the proximal portion of the small colonleading to an insidious onset of clinical signs and a gradualdistension of the intestine oral to the obstruction with gas andingesta (Edwards 1997; Schumacher and Mair 2002; Pierce2009; Plummer 2009).

Enteroliths, like faecaliths or faecal impactions of the smallcolon, may be removed via enema and manualmanipulation, if palpable (Pierce 2009). Surgical treatment isoften required for resolution of an enterolith obstruction.Typically, a ventral midline incision is performed and theenterolith is either manipulated retrograde into the large colonwhere a right dorsal colon or pelvic flexure enterotomy isperformed for removal, or a small colon enterotomy isperformed directly over the enterolith (Schumacher and Mair2002; Rakestraw and Hardy 2006).

We describe a case of a distal small colon obstructionwith an enterolith that we were unable to resolve standingwith enemas and digital manipulation, or by extraluminalmassage through a ventral midline incision. We performed aparainguinal approach to the abdomen to remove theenterolith and present the case as an additional surgicalapproach for resolving distal small colon obstructions. To ourknowledge this is the first reported case of removal of a smallcolon enterolith through a parainguinal approach.

Case historyA 3-year-old American Quarter Horse colt (435 kg) wasreferred for evaluation of signs of colic of 12 hours’ duration.The colt had been showing mild signs of colic and was treated

with 500 mg of flunixin meglumine (Banamine)1 by the barnmanager. For examination the referring veterinarian sedatedthe horse with 200 mg xylazine (Anased)2 and 4 mgbutorphanol (Torbugesic)3. It was reported that on initialexamination, the horse appeared 5% dehydrated and had anelevated heart rate (52 beats/min). Transrectal palpation ofthe abdomen noted only gas distended large intestine. Anasogastric tube was passed, and no net gastric refluxwas obtained so mineral oil and water were administered.Due to continued signs of colic within a few hours, thereferring veterinarian placed an intravenous catheter andadministered 120 mg N-butylscopolammonium bromide(Buscopan)4, and 20 l of intravenous fluids. Because the horsecontinued to show intermittent signs of colic despite therapy, itwas referred to our hospital for further evaluation.

Clinical findings and diagnosisAt admission, the colt was displaying signs of mild abdominalpain (pawing, looking at his side). Heart rate was elevated at56 beats/min, he had a slightly prolonged capillary refill time of3 s, and oral and scleral mucous membranes were injected.Borborygmi were decreased to absent in all 4 quadrants and hisabdomen was markedly distended. A nasogastric tube wasagain placed with no net reflux obtained. During abdominalultrasonic examination no abnormalities were noted. Duringtransrectal examination of the abdomen, an extremely firmobject obstructing the small colon, estimated to be 8 cm indiameter and within reach (approximately 25 cm) from theanus was directly palpated.

Abnormalities of blood biochemical analysis (StatProfileCritical Care Xpress)5 included: hypocalcaemia 1.38(reference range [rr] 2.6–3.3) mmol/l, hyperglycaemia 1.77 (rr0.62–1.14) g/l, hypomagnesaemia 0.5 (rr 0.7–1.1) mmol/l andan elevated lactate of 3.3 (rr 0.38–1.12) mmol/l. Haematologyresults were within normal limits. Abdominocentesis was notperformed at this time because we believed that the severeabdominal distension increased the risk of enterocentesis.

Several attempts were made to remove or break up theobstruction within the small colon per rectum with the horsestanding after distending the rectum and small colon withlubrication (Lubrivet)6 without success. Because of continuedsigns of pain in the horse, progressive abdominal distension,the risk of rectal tear, the possibility of multiple foreign bodiesbeing present, and inability to remove or break down theobstruction per rectum, the decision was made to perform aceliotomy. Potassium penicillin (22,000 iu/kg bwt i.v.)7,gentamicin sulphate (6.6 mg/kg bwt i.v.)8, and tetanus toxoid(once, i.m.)3 were given preoperatively.

442

© 2012 EVJ Ltd

EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2013

Surgical techniqueThe colt was induced using xylazine (1.1 mg/kg bwt i.v.)2,ketamine (2.2 mg/kg bwt i.v.)3 and diazepam (0.5 mg/kgbwt)9. General anaesthesia was maintained with isoflurane12

and oxygen. The colt was positioned routinely in dorsalrecumbency and the surgical field aseptically prepared. Theabdomen was entered using sharp dissection along theventral midline (Fischer 2006). The incision extended from theumbilicus 15 cm cranially.

During exploration of the abdomen, the caecum andascending colon were found to be severely distended withgas but minimal faecal material. Both were decompressedusing a 16 gauge needle. A single, 8 cm in diameter ovalobstruction was located within the distal small colon. The smallcolon containing the obstruction could be visualised within theabdomen and appeared grossly normal externally. Initially,because the obstruction could not be externalised from theabdomen through the ventral midline incision, manualremoval per rectum was again attempted by a nonsterileassistant instilling lubricant and water into the rectum throughthe anus while the small colon oral to the obstruction wasoccluded internally by the surgeon. Water and lubricantmoved past the obstruction. These efforts were unsuccessfuldespite successful distention of the small colon oral and aboralto the obstruction, probably due to its irregular shape. Due toits distal location and the short mesocolon at that location, theobstruction could not be exteriorised through the ventralmidline incision, despite extending the ventral midline incisioncaudally 10 cm, and attempts to manipulate the obstructionorad along the small colon were also unsuccessful. Ataeniotomy was not attempted, due to a lack of adequatevisualisation and the risk of faecal contamination.

It was noted that the foreign body could easily bemanipulated to lie below and medial to the inguinal rings, justcranial to the pelvic brim. The right inguinal region wasaseptically prepared and draped in a routine sterile manner. A14 cm skin incision was made in the right parainguinal region(Fig 1) parallel and 2 cm cranial to the right external inguinalring beginning at the lateral border of the right externalinguinal ring and continuing caudomedially toward midline

(Beard 2004). The external sheath of the rectus abdominus wasincised sharply, after which the internal abdominal obliquemuscle was bluntly dissected along the length of the fibres(Fig 2). The surgeon’s fingers were used to bluntly enter theperitoneum. The distal portion of the small colon containingthe obstruction was elevated to the level of the parainguinalskin incision by an assistant. At the level of the obstruction, thelength of the mesentery of the small colon preventedcomplete exteriorisation of the small colon through theparainguinal incision so it was held in place by a sterileassistant throughout the procedure. The area surrounding thesmall colon was packed off with moist sterile towels. A 10 cmenterotomy was performed in the antimesenteric taenia of thesmall colon over the obstruction. The obstruction, appearing tobe an enterolith (Fig 3), was removed and the colon wasclosed using 2-0 polyglactin 910 suture (Vicryl)11 in 2 layers; asimple continuous pattern, over sewn with a minimallyinverting, continuous Lembert pattern, keeping all bites within0.5 cm of the incision line. The first layer of the closure included

Fig 1: Diagram of the parainguinal approach. The black linerepresents the location of the inguinal ring and the white line is thelocation of the parainguinal incision.

Aponeurosis of the external abdominal oblique

Fig 2: View of the parainguinal approach in a cadaver after the skinhas been incised and the subcutaneous tissues dissected away toshow the aponeurosis of the external abdominal oblique.

Fig 3: Enterolith with a No. 20 scalpel blade for size reference. Thelayer of faeces that coated the faecalith has been removed,showing the irregular, mineralised core.

© 2012 EVJ Ltd

443EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2013

the mucosal layer. After closure of the enterotomy the outercircumference of the small colon at the site of the enterotomywas decreased in size by approximately 10%. A significantamount of faecal contamination of the parainguinal surgicalsite occurred from faecal material surrounding the enterolithso prior to returning the small colon to the abdomen the boweland incision were gently lavaged with 5 l of sterile polyionicfluid (Plasma-Lyte A)12. The rectus abdominus muscle wasclosed with 0 polyglactin 910 (Vicryl) in a simple continuouspattern, and the external rectus sheath was closed with asimple continuous pattern using No. 3 polyglactin 910.Subcutaneous tissues were closed using 0 polyglactin 910 in asimple continuous pattern and the skin was closed using ahorizontal mattress pattern and 2-0 polypropylene (Prolene)11.The abdomen was then lavaged with 5 l of sterile polyionicfluid and the abdomen was infused with 1 l ofcarboxymethylcellulose (CA194)13. A 24-French drain wasplaced 6 cm to the left of the cranial end of thelinea albaincision, which is routine for contaminated procedures at thishospital. It was sutured in place using No. 2 polypropylene(Prolene) in a finger trap pattern. The ventral midline incisionwas closed routinely (Fig 4).

A stent bandage was placed for protection of the midlineincision during recovery using No. 2 polypropylene. Totalsurgical time from first incision was 4 h 10 min which wasprolonged when compared to the average surgical time of90 min for exploratory celiotomies at our institution. Recoveryfrom anaesthesia was unremarkable. After recovery, aHeimlich valve (No. 373460)14 was placed on the end of theabdominal drain, along with a padded elastic abdominaltape bandage (Elastikon)15.

Initial post operative careThe colt was administered maintenance i.v. crystalloid fluids(60 ml/kg bwt/day for 4 days)12, broad spectrum antibioticsincluding: potassium penicillin (22,000 iu/kg bwt i.v., every 6 hfor 7 days)7, gentamicin (6.6 mg/kg bwt i.v., every 24 h for 7days)8, metronidazole (20 mg/kg bwt per os, every 8 h for 6days)16, i.v. lidocaine (1.3 mg/kg bwt bolus over 15 minthen 0.05 mg/kg bwt/min for 3 days)8, flunixin meglumine

(1.1 mg/kg bwt i.v. every 12 h for 3 days, then 0.5 mg/kg bwti.v. every 12 h for 3 days)1, enoxaparin (Lovenox, 0.35 mg/kgbwt subcut. every 12 h for 48 h)17 and omeprazole(Gastrogard, 4.0 mg/kg bwt per os every 24 h for 9 days, then1.0 mg/kg bwt per os every 24 h for the remaining duration ofhospitalisation)18. The morning following surgery the horse hada decreased white blood cell count (3.5 ¥ 109/l) characterisedby a neutropenia (1.8 ¥ 109/l). This resolved by 72 h postoperatively. Antibiotic administration was prolongedcompared to our hospital’s standard post enterotomyprotocol due to intraoperative contamination during faecalithremoval, and was maintained until systemic white blood cellmeasurements for the patient were within normal limits andculture results of the peritoneal fluid and drain were negative.

Ice boots were placed on all 4 feet for 48 h after surgery asa preventative measure for laminitis. The abdomen wasflushed with 10 l of sterile polyionic fluids12 beginning 12 h aftersurgery, and repeated every 24 h for 3 days post operatively,when the drain was removed and submitted for culture.Abdominal ultrasonography performed post operatively werewithin normal limits. Beginning 72 h after surgery the colt waswalked for 10 min every 3 h.

Every 24 h for the first 72 h after surgery 1 l of mineral oil and2 l of balanced electrolyte water were administered through anasogastric tube. Beginning 3 days after surgery, a completepelleted feed (Equine Senior)19 soaked in water was fed. Theamount of pelleted feed was gradually increased over 5 daysuntil 2 kg of soaked feed was fed 4 times daily; this wassupplemented with grazing during his daily handwalks.

During convalescence, the horse had a good appetite,was drinking normally and urinating and defaecatingnormally.

OutcomeAfter surgery, mild oedema of the parainguinal, ventral midlineand the distal portion of all 4 limbs developed. Wrapping thedistal limbs with support wraps and handwalking resolved theoedema. Two days post operatively the colt developed afever (39.2°C), which persisted for 12 h. Differential diagnosesfor the elevated temperature were peritonitis, pneumonia,colitis or post surgical inflammation. Septic peritonitis was ruledout with a negative culture of the abdominal drain andperitoneal fluid. Pneumonia and colitis were an unlikely causeof fever because of the absence of other clinical signsassociated with these conditions.

Prior to returning feed, rectal palpation and colonoscopywere performed. Palpation revealed severe mucosal oedemaat the site of colotomy, to the point that only 2 fingers could beplaced into the lumen of the small colon at the site.Colonoscopy confirmed these findings. Concerns overdevelopment of an adhesion at the location, or of apermanent stricture forming and leading to persistentimpactions at the site led to the decision to perform repeatpalpations and colonoscopy every 2–3 days until discharge, 15days post operatively. Prior to discharge, oedema in thecolonic mucosa had resolved; however, the section of smallcolon where the enterotomy had been performed onlyallowed the passage of 3 fingers. The small diameter of thesmall colon at the surgery site led to the recommendation tocontinue feeding a complete pelleted feed as a mash, withfresh grass and no coarse feed, such as hay. Six months postoperatively, the referring veterinarian reported that during

Fig 4: Post operative view of the patient standing displaying the 2surgical incisions: the traditional ventral midline approach (solidarrow) and the parainguinal approach (hollow arrow).

© 2012 EVJ Ltd

444 EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2013

rectal examination he was able to pass his hand normallythrough the small colon at the site of the enterotomy. Theowners began feeding hay at 8 months post surgery and thehorse has shown no further signs of colic or othercomplications.

DiscussionEnteroliths obstructing the small colon are associated withfeeding alfalfa hay, limited access to pasture grazing andconfinement housing for more than 50% of the day (Pierce2009). The various surgical options to treat small colonobstruction caused by enteroliths include enterotomy with orwithout prior retrograde movement of the enterolith to an areawhere it can be removed or normograde movement to therectum for evacuation (Edwards 1997; Schumacher and Mair2002; Rakestraw and Hardy 2006; Pierce 2009). These surgicalapproaches are often unsuccessful because the odd shape ofthe enterolith makes it difficult to move without tearing thesmall colon. Partial teniotomy, or enemas with lubricants orwater, with or without distention of the small colon, aredescribed to assist movement of the enterolith (Schumacherand Mair 2002; Rakestraw and Hardy 2006).

The small colon is approximately 3.5 m long and issuspended by a long, fatty mesocolon, which allows goodsurgical access to all but the most proximal and distal portions,where the mesocolon is significantly shorter. This mesocoloncourses along the left surface of the root of the mesentery,finally attaching on midline as it enters the pelvic canal.Surgical reports for removal of objects from the inaccessibleportions of the proximal and distal small colon are few. A leftparamedian approach for removal of a proximal small colonfaecalith has been reported (de Oliveira Dearo et al. 2009).This report discussed concerns over the size of the dual incisionson the ventral abdomen leading to poor healing and possibleherniation. Our surgical approach for this distal enterolith wasthrough a right parainguinal incision. The decision to create aright sided parainguinal incision site was based on the ability toeasily move the enterolith to the desired celiotomy siteintraoperatively. However, it may be preferable to perform aleft parainguinal incision for more oral obstructions based onthe anatomy of the small colon mesentery, and this should bekept in mind for future cases.

We chose to manage this patient aggressively postoperatively for 2 reasons. First, we had concerns over thecolt developing a peritonitis based on the amount ofcontamination we had at surgery and the fever he developedpost operatively. We chose to confirm the lack of infection byculture of the abdominal drain and repeated blood work priorto halting antimicrobial therapy. Second, we felt that theextreme abdominal distension that occurred preoperativelycould have had negative cardiovascular effects affectingboth gastrointestinal and systemic perfusion, increasing the riskof endotoxaemia and post operative ileus even without aprimary infection. Enoxaparin has been shown in equinepatients to reduce the risk of laminitis and coagulationdisorders in post operative colic, and is administered to horsesin our clinic at risk for endotoxaemia and reperfusion injury (dela Rebière de Pouyade et al. 2009). In addition, coagulationabnormalities are common in horses with ischaemic diseaseand peritonitis, and low molecular weight heparin may reducedeposition of fibrin in the lungs, multiorgan dysfunction andjugular thrombosis (Feige et al. 2003; Cotovio et al. 2007).

The major post operative complication associatedwith this surgery was the oedema and acute strictureassociated with the site of small colon enterotomy. Stricture isa commonly reported complication of small colon surgeryperformed through any abdominal approach and currentsurgical technique is aimed at reducing the risk of strictureformation (Schumacher and Mair 2002; Rakestraw and Hardy2006). Other factors that may contribute to stricture formationcould include the degree of intestinal inflammation, theamount of intraoperative bowel manipulation and the size ofthe suture and suture bite (Edwards 1997). While 2-0 suture isthe standard for small colon enterotomies, smaller suture sizemay be considered to improve luminal diameter (Rakestrawand Hardy 2006). Careful reintroduction of feed reduces therisk of impaction and dehiscence at the enterotomy site(Rakestraw and Hardy 2006). Current recommendations toreduce the risk of impaction at the site of anastomosis includefeeding a laxative diet, oral fluids, pelvic flexure enterotomyand colonic evacuation, and delayed time to first feeding(Prange et al. 2010). While evacuation of the ascending colonwas not required in this case, due to the minimal feed presentin ascending colon, we did feed a laxative diet, and instituteda slow return to feed during the horse’s recovery. For this horse,because we were able to palpate the enterotomy site rectallywe could make clear recommendations on diet based on thepalpated size of the small colon lumen.

A ventral parainguinal abdominal approach should beconsidered in cases of distal small colon enterolith, faecalith orforeign body obstruction that cannot be relieved through atraditional ventral midline approach. The parainguinalapproach offers advantages over other approaches to thecaudal abdomen because it avoids the superficial epigastricand pudendal vessels commonly encountered with caudalmedian or paramedian approaches. The parainguinalapproach also reduces the formation of dead spaceproduced during the paramedian and caudal medianapproaches when the penis has to be retracted in males(Beard 2004). Other post operative complications noted withthe parainguinal approach were consistent with those seen inour case, involving oedema formation at, and cranial to, theincision (Beard 2004). In our case, and in the case of theprevious report, this was easily managed with nonsteroidalanti-inflammatory drugs and cold hosing, respectively.

This report provides evidence for the successful useof a parainguinal approach for removal of obstructions fromthe distal small colon. Access to the bowel was possible, andthe complications seen post operatively were similar to thosenoted for parainguinal approaches used for other reasons, orfor other small colon surgeries. Surgery time for removal of theenterolith in this case could have been shortened if we hadmade the decision to use a parainguinal approach sooner.This stresses the importance of abandoning futile proceduresand proceeding with novel surgical approaches for uniquesituations.

Authors’ declaration of interestsNo conflicts of interest have been declared.

Manufacturers’ addresses1Schering Plough Animal Health, Union, New Jersey, USA.2Lloyd Laboratories, Shenandoah, Iowa, USA.3Fort Dodge Animal Health, Fort Dodge, Iowa, USA

© 2012 EVJ Ltd

445EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2013

4Boehringer Ingelheim, St Joseph, Missouri, USA.5Nova Biomedical, Waltham, Massachusetts, USA.6Butler Scheir Animal Health, Dublin, Ohio, USA.7Baxter Healthcare Corp., Deerfield, Illinois, USA.8Vedco Inc., St Joseph, Missouri, USA.9Hospira, Lake Forest, Illinois, USA.10Piramel Healthcare, Bethlehem, Pennsylvania, USA.11Ethicon Inc., Somerville, New Jersey, USA.12Baxter Healthcare Corp., Deerfield, Illinois, USA.13CA194, Spectrum Chemical Mfg. Corp., Gardena, California, USA.14BD, Franklin Lakes, New Jersey, USA.15Johnson & Johnson, New Brunswick, New Jersey, USA.16Pliva Inc. Pomona, New York, USA.17Sanofi-aventis U.S. LLC, Bridgewater, New Jersey, USA18Merial LLC, Duluth, Georgia, USA19Purina Mills LLC, St Louis, Missouri, USA

ReferencesBeard, W. (2004) Parainguinal laparocystotomy for urolith removal in

geldings. Vet. Surg. 33, 386-390.

Cotovio, M., Monreal, L., Navarro, M., Segura, D., Prada, J. and Alves, A.(2007) Detection of fibrin deposits in tissues from horses with severegastrointestinal disorders. J. Vet. Intern. Med. 21, 308-313.

De la Rebière de Pouyade, G., Grulke, S., Detilleux, J., Salciccia, A.,Verwilghen, D.R., Caudron, I., Gangl, M. and Serteyn, D.D.A. (2009)Evaluation of low-molecular-weight heparin for the prevention of

equine laminitis after colic surgery. J. Vet. Emerg. Crit. Care 19,113-119.

De Oliveira Dearo, A.C., Gomes, R.G., Araujo, R.G., Reichmann, P.,Cosenza, M. and Coneglian, M.M. (2009) Surgical removal ofa descending (small) colon foreign body through a secondaryparamedian approach. J. Equine Vet. Sci. 3, 155-159.

Edwards, G.B. (1997) Disease and surgery of the small colon. Vet. Clin. N.Am.: Equine Pract. 2, 359-376.

Feige, K., Schwarzwald, C.C. and Bombeli, T. (2003) Comparison ofunfractioned and low molecular weight heparin for prophylaxis ofcoagulopathies in 52 horses with colic: a randomized double-blindclinical trial. Equine Vet. J. 35, 506-513.

Fischer, A.T. (2006) Colic: diagnosis, preoperative management andsurgical approaches. In: Equine Surgery, 3rd edn., Eds: J.A. Auer andJ.A. Stick, Saunders Elsevier, St Louis. pp 393-394.

Pierce, R.L. (2009) Enteroliths and other foreign bodies. Vet. Clin. N. Am.:Equine Pract. 25, 329-340.

Plummer, A.E. (2009) Impactions of the small and large intestines. Vet.Clin. N. Am.: Equine Pract. 25, 317-327.

Prange, T., Holcombe, S.J., Brown, J.A., Dechant, J.E., Fubini, S.L.,Emberston, R.M., Peroni, J., Rakestraw, P.C. and Hauptman, J.G.(2010) Resection and anastomosis of the descending colon in 43horses. Vet. Surg. 39, 748-753.

Rakestraw, P.C. and Hardy, J. (2006) Large intestine. In: Equine Surgery,3rd edn., Eds: J.A. Auer and J.A. Stick, Saunders Elsevier, St Louis.pp 436-478.

Schumacher, J. and Mair, T.S. (2002) Small colon obstructions in themature horse. Equine Vet. Educ. 1, 19-28.

© 2012 EVJ Ltd

446 EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2013

Advertisers’ Index AAEP Convention ………………………Cover 4 AAEP Foundation ………………………486 AAEP Partners ………………………….Cover 2 Hallmarq ………………………………..450A Kentucky Performance Products ……….XIV Luitpold Animal Health ………………...441 Merial …………………………………..XIII, 482A Nutrena …………………………………450B Platinum Performance ………………….484 Purina …………………………………...482B SmartPak ………………………………..Cover 3 Saddlite ThoroVet ………………………467

Marketplace Advertisers Booth at 59th Annual Convention

Centurion Systems ………………………1625/1627Cinch Chix ………………………………No booth CRC Press/Taylor & Francis Group …….No booth Dr. Matthew Eliott ………………………No booth Equine Diagnostic Solutions …………….616 ImproMed ……………………………….1679/1778 Kentucky Equine Research ……………...2155/2157 KRUUSE ………………………………..1772 Magnus Magnetica ………………………2254Saddlite ThoroVet ……………………….1867 Texas Farriery Supply ……………………910