Veterinary Surgery, 16, 4, 251-254, 1987

Surgical Repair of an Esophageal Stricture in a Horse

DIANE CRAIG, DVM, and RORY TODHUNTER, Bvsc, MS

An esophageal stricture was diagnosed in a 9-month-old quarterhorse by esophago- scopy and positive pressure contrast esophagography. Medical management and two attempts at surgical intervention were unsuccessful. The initial surgical technique used was a linear esophagotomy, rnucosal resection and anastomosis, and closure of the muscular tunic, which resulted in a more severe stricture. The second surgical procedure was interruption of the stricture cicatrix by a single linear esophagotomy and primary closure of only the esophageal muscular tunic. This technique resulted in an increased lumen diameter, but failed to adequately resolve the stricture. Successful resolution of the stricture with return to a normal diet was achieved by a two stage repair using formation of an esophagostomy to stabilize the esophagus, followed by fenestration of the mucosal-submucosal cicatrix. Six months postoperatively, the horse was asympto- matic on a normal diet.

H E SURGICAL MANAGEMENT of esophageal stric- T ture has been described in most domestic species. In the horse, the following three types of lesions are identified at surgery: fibrosis or scarring of the tunica muscularis or adventitia; annular webs or fibrous rings in the mucosa/submucosa; and circumferential lesions involving the full thickness of the esophageal wall.' Strictures originating primarily in the esophageal mus- cular tunic or adventitia respond to surgical techniques such as myotomy, myoplasty, and excision of scar tis- sue.',' Mucosal-submucosal or full thickness strictures are more difficult to resolve surgically, although iso- lated case reports describe success with patch graft- ing:' and end-to-end anastomosis after either partial4,; or complete resection."-" The high rate of surgical fail- ure reported in most species after invasion of the esophageal lumen can be attributed to the rapid turn- over of esophageal mucosa, movement during degluti- tion, tension on suture lines, and the lack of a serosal surface to prevent leakage."" Bougienage of difficult mucosal strictures is a useful technique in humans" and small anirnals,l3 and although this procedure has been described in the horse, the results were not successful . I 4

This article describes resolution of a mucosal-sub- mucosal stricture by formation of a mature esophagos- tomy and subsequent fenestration of a mucosal-sub- mucosal cicatrix.

Case Report

A 9-month-old quarterhorse was presented with the complaint of regurgitation since birth. The horse ex- hibited intermittent esophageal obstruction character- ized by bruxism, sialorrhea, copious nasal discharge, and violent coughing. Although each episode resolved spontaneously after 3 to 5 days, the episodes had in- creased in frequency.

On admission, the horse had mucopurulent nasal discharge, tachypnea, and fever. Esophagoscopy with a 16 mm fiberoptic endoscope identified a focal nar- rowing of the Lumen and a 1 cm circumferential muco- sal ulceration 60 cm from the external nares (Fig. 1). A positive pressure contrast esophagram (PPCE)' dem- onstrated pre-stenotic dilatation and a focal 8 mm di- ameter stricture at the level of the third cervical verte- brae (Fig. 2). Thoracic auscultation and radiography confirmed a cranioventral bronchopneumonia.

The horse was hospitalized for medical management which included trimethoprim-sulfadiazine (30 mg/kg orally once daily) and a diet of slurry made from alfalfa pellets. He responded well to therapy and was dis- charged in 7 days with recommendations for 14 days of antibiotic therapy and re-evaluation after 60 days of dietary management.

The horse was readmitted 150 days later with a cer- vical esophageal feed impaction. The obstruction was

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From the New York State College of Veterinary Medicine, Cornell University, Ithaca, New York. Reprint requests: Diane Craig, DVM, New York State College of Veterinary Medicine, Cornell University, Ithaca, NY 14850.

251

252 SURGICAL REPAIR OF AN ESOPHAGEAL STRICTURE IN A HORSE

Fig, 1. with circumferential mucosal ulceration.

Endoscopic view of the esophagus at the stricture site

relieved with hydropulsion and lavage. Results of endoscopic examination of the esophagus and PPCE confirmed the same stricture location. Clinical and ra- diographic signs of aspiration pneumonia were more severe and a hypochloremic, hyponatremic, compen- sated metabolic alkalosis was identified. Treatment with oral administration of electrolyte^,'^ penicillin (22,000 IUikg), gentamicin ( 2 mg/kg), and dietary management as previously described was initiated. Surgical exploration of the stricture was delayed for 10 days until clinical signs of respiratory disease resolved.

A longitudinal esophagomyotomy was performed under general anesthesia, and the stricture was identi- fied as a fibrous 1 cm mucosal-submucosal cicatrix. A 2 cm mucosal resection and anastomosis was per-

The tunica muscularis was closed and a feeding tube was secured through a distal esopha- gostomy.” Postoperative management included con- tinued antibiotics and slurry diet with sodium, potas- sium, and chloride electrolyte supplementation.

Fourteen days after surgery, antibiotic adrninistra- tion was discontinued, the esophageal feeding tube was removed, and oral slurry diet was begun. Postop- erative complications seen were laminitis, left laryn- geal hemiplegia, and dehiscence of the mucosal repair, which could be visualized endoscopically . Healing of the esophagostomy incision was complete in 14 days and the esophagostomy site healed by second inten- tion in 28 days.

Esophagoscopy 28 days postoperatively showed complete mucosal healing of the anastomotic site but no resolution of the stricture. PPCE at 28 and 54 days postoperatively demonstrated a lumen diameter of 5 mm at the stricture site in contrast to the original pre- operative (8 mm) and 5 day postoperative (16 mm)

films. The horse continued to show regurgitation and intermittent obstruction.

A second surgical repair was attempted 75 days after the mucosal resection and anastomosis. A 5 day course of trimethoprim-sulfadiazine was begun 12 hours preoperatively. Surgical exploration showed minimal periesophageal scarring, and a fibrous muco- sal-submucosal cicatricial scar was identified at the anastomotic site. The mucosa was incised longitudi- nally through the cicatrix to allow advancement of the nasogastric tube beyond the stricture. The tunica muscularis was apposed over the mucosal defect with synthetic absorbable suture in a simple interrupted pattern.

Postoperatively, the horse was fed a slurry through an indwelling nasogastric tube. Two days after sur- gery, the tube became dislodged necessitating intrave- nous fluid replacement therapy until oral alimentation with slurry was resumed o n the fifth postoperative day. Complications of the second surgical procedure included incisional dehiscence, periesophageal infec- tion, and esophageal fistula formation.

Esophagoscopy and contrast radiography 21 and 47 days after the second surgery identified partial resolu- tion of the stricture with widening of the esophageal lumen at the stricture site to 12 mm. The horse main- tained an adequate weight on the slurry ration, but continued to obstruct on firmer feeds or roughage. The owners objected to permanent dietary modification and a third surgical repair was attempted.

In the first stage of this repair, a 30 mm ventral longitudinal esophagotomy was performed centered at the mucosal cicatrix and a 16 mm outside diameter feeding tube was secured in place through the incision. Postoperative management included the administra- tion of a slurry with electrolyte replacement through the feeding tube, daily wound care, and trimethoprim- sulfadiazine therapy for 3 days. No postoperative complications were seen.

The feeding tube was removed after 14 days and a mature 40 mm long esophageal fistula was present (Fig. 3). A hemicircumferential cicatrix involving 80% of the mucosal circumference could still be palpated through the fistula. In the second stage of this repair, the horse was sedated and the mucosal-submucosal cicatrix was incised longitudinally at 5 mm intervals through the fistula. Digital palpation after fenestration confirmed an increase in lumen diameter. Mixed grass hay was offered immediately after the surgical proce- dure which passed successfully beyond the stricture site although smaller feed boluses escaped through the fistula. Free choice hay diet was maintained, the esophagostomy healed by second intention in 30 days, and no evidence of esophageal obstruction was observed.

CRAIG AND TODHUNTER 253

Fig. 2. PPCE at the time of initial presentation demonstrates a focal esophageal stricture at the level of the third cervical vertebrae.

Esophagoscopy 46 and 60 days after the fenestration showed complete mucosal healing and no obstruction to passage of the endoscope. A PPCE at 60 days post- operatively showed a 35 mm lumen with resolution of the stricture (Fig. 4). The horse was discharged on a hay diet. No recurrence of obstruction was reported in the subsequent year.

Discussion

Most equine esophageal mucosal-submucosal stric- tures occur secondary to circumferential mucosal ul- ceration produced by ischemic necrosis during pro- longed feed impaction.'*'8-1Y The depth and length of the ulceration dictates the severity of the resultant stricture. Medical management with anti-inflammatory drugs and feeding of a slurry diet in the first 60 days after an insult can prevent chronic esophageal stricture formation. lY Surgical intervention should be delayed for 60 days or until the lumen at the strictured site achieves maximal diameter and mucosal healing is complete.1Y Permanent dietary management may be successful in cases of persistent strictures.

A primary objective in surgical repair of esophageal strictures in the horse is to permit the ingestion of a normal roughage diet. While strictures of the esopha- gus due to fibrosis of the tunica muscularis or adventi- tia have a good prognosis with surgical repair, muco- sal-submucosal lesions are more difficult to resolve surgically and complications are documented for most surgical procedures. Isolated cases of successful re- section and anastomosis have been reported, but per- manent dietary management was required suggesting incomplete resolution of the stricture.6j8 Mucosal re-

Fig. 3. PPCE 2 weeks after placement of an esophagostomy tube and fenestration of the cicatricial scar shows a mature esophageal fistula.

section and anastomosis has met with success in one clinical report ,5 but experimental mucosal resection and anastomosis in the normal esophagus produced unacceptable complications including consistent post- operative stricture formation, dehiscence, perieso- phageal infection, fistula formation, and death.IY Esop- hageal patch grafting with the sternocephalicus muscle over a mucosal defect in one case resolved the stric- ture but postoperative infection, fistula formation, and dehiscence were r e p ~ r t e d . ~

The surgical intervention in this case included two unsuccessful attempts at stricture repair with resolu- tion after a third surgical procedure. Mucosal resec- tion and anastomosis produced a more severe stricture with results similar to those described experimen- tally.IY Interruption of the cicatricial scar in the second surgery provided partial resolution of the stricture, but permanent dietary modification was still required.

In the third surgical procedure, the stricture cicatrix was interrupted by placement of a feeding tube through a ventral esophagostomy. The placement of an esophageal feeding tube in the ventral cervical re- gion of the horse is an acceptable method for extraoral feedingI7 and in this case was also intended to provide relief of the stricture by formation of a traction diver- ticulum. A traction diverticulum is a benign condition in which redundant mucosa forms a wide base at the esophagus and tapers to the skin and does not entrap ingesta.20 The condition can be created by healing of an esophageal fistula after esophagostomy , rupture, or surgical intervention. 17,20

In this case, a mature fistula was recognized at 14 days and had begun to form a traction diverticulum. Although some relief of the stricture was observed, the

254 SURGICAL REPAIR OF AN ESOPHAGEAL STRICTURE IN A HORSE

Fig. 4. t h e stricture.

PPCE af ter healing of t h e fistula s h o w s resolution of

mucosal-submucosal cicatricial scar still compro- mised the esophageal lumen. Longitudinal fenestration at 5 mm intervals divided the fibrous cicatrix in a man- ner similar to the traumatic interruption accomplished with vigorous bougienage. Longitudinal incisions of the mucosa are reported to heal without stricturez1 and it is hypothesized that fenestration of the cicatrix al- lowed for normal mucosa to regenerate in the longitu- dinal mucosal defects. Roughage was provided imme- diately after fenestration to provide natural bougienage of the site during healing. Nursing care and time of incisional healing were comparable to those reported in unsutured linear esophagotomy and esophagostomy procedures for feeding purposes. 17, 20, 21 Complications encountered in other procedures such as periesopha- geal infection, anastomotic dehiscence, and restricture were not seen. The formation of an esophageal fistula stabilized the esophagus before the fenestration proce- dure and provided certain advantages to healing of the esophagus. Surgeons describe a similar technique of fistulization to immobilize the esophagus before pri- mary surgical repair.22 Fistulization decreases move- ment during bolus formation which is one of the phys- iologic barriers to healing of the esophagus. In this case, the mature fistula also isolated surrounding tis- sues from contamination and provided an avenue of drainage. Periesophageal infection was not seen de- spite mucosal invasion and early return to oral ali- mentation. The fistula provided access to the mucosal cicatrix for fenestration, served as an extraoral means of alimentation, and may have contributed to stricture relief during formation of a traction diverticulum (Fig. 3 ) .

Traditional surgical strategies for correction of eso- phageal mucosal-submucosal strictures can produce

unacceptable results with potentially fatal complica- tions. The surgical technique described here used lon- gitudinal incisions to interrupt the mucosal-submu- cosal cicatrix. The use of a first stage esophagostomy stabilized the esophagus, provided access for fenestra- tion, and created a barrier to contamination of the periesophageal tissues.

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