EQUINE VETERINARY EDUCATION / AE / AUGUST 2020


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Materials and methods


Case selection Medical records from January 2004 to December 2016 from the Koret School of Veterinary Medicine were searched for cases which were diagnosed with FB obstruction of the large or small colon. Equids were included in the study if a definitive diagnosis of FB was made during exploratory laparotomy or necropsy. Keywords used during the search included colic, foreign


body and twine.


Medical records review Data obtained from the records included age, breed, sex, pregnancy status, duration of colic prior to admission and season of the year when the horse was admitted. Season was defined as follows: autumn (September–November), winter (December–February), spring (March–May) and summer (June–August). Additional information obtained included physical examination findings, haematological and serum biochemical analysis, nasogastric intubation and rectal palpation findings. Data regarding surgery included the interval from admission to surgery, location of the FB (large or small colon), composition of the FB, surgery technique used to remove the FB, additional pathologies identified in surgery, performance of a pelvic flexure enterotomy, duration of surgery and the surgeon performing the surgery. Additionally, information regarding post-operative complications, hospitalisation time and outcome was obtained.


Outcome Short-term survival was defined as survival to the time of discharge and long-term survival was defined as alive 1 year after surgery. Long-term follow-up was obtained by telephone interview with the owner.


Procedure Intravenous fluid therapy was initiated before surgical preparation and was continued during surgery. Flunixin meglumine (1.1 mg/kg bwt, i.v.), penicillin G sodium (22,000 U/kg bwt, i.v.) and gentamicin (6.6 mg/kg bwt, i.v.) were given before surgery. The surgical approach in the vast majority of the cases was a standard ventral midline incision under general anaesthesia, however, one case was operated under standing sedation through the left flank. Horses were sedated with xylazine hydrochloride (0.5 mg/kg bwt, i.v.) and butorphanol tartrate (0.01 mg/kg bwt, i.v.). Anaesthesia induction was achieved with administration of ketamine hydrochloride (2.2 mg/kg bwt, i.v.) and diazepam (0.05 mg/kg bwt, i.v.) and maintained with isoflurane in 100% oxygen. The horse operated under standing sedation was restrained in stocks and sedated with a constant rate infusion of 10 mg of butorphanol tartrate and 10 mg of detomidine HCl in 1 L isotonic saline solution. The rate of infusion was varied according to the horse’s responses to the surgical stimuli. In addition, local anaesthesia using 2% lidocaine applied as a line block was administered at the intended incision site for the horse treated under sedation. The techniques employed to facilitate removal of the FB


depended on the location of the obstruction. For FBs lodged within the small colon, in areas that could be exteriorised, removal was achieved by means of: 1) high enema combined with external massage to break the impaction


around the FB and evacuate it via the anus; 2) enterotomy through the antimesenteric taenia. Closure of the enterotomy site was performed using 2-0 polydioxanone in a full thickness simple continuous pattern, followed by a Cushing continuous pattern. 3) small colon resection and anastomosis of the damaged segment including the FB. Anastomosis was performed using closed, one-stage, stapled, functional, end- to-end resection and anastomosis as described previously (Anderson et al. 2012). Foreign bodies located in the large colon or oral small


colon were removed using one of the following techniques: 1) fluid distention using high enema or pelvic flexure enterotomy to manipulate the FB so it could be extracted through a pelvic flexure enterotomy; 2) Enterotomy at the location of the FB. The latter was performed in cases where the FB was adhered to the mucosa and fluid distention failed to allow manipulation of the foreign body, or when the FB was too large to evacuate via a pelvic flexure enterotomy. Closure of enterotomy sites was achieved by suturing the wall of the intestine in two layers as described earlier. Prior to performing small colon or large colon enterotomy (excluding the pelvic flexure), the planned enterotomy site was isolated from the abdomen using saline-soaked sterile laparotomy sponges and a nylon drape was sutured around the incision site using a size 3-0 polydioxanone suture material (Fig 1).


Data analysis Statistical analyses were performed by using analytic computerised software- Statistix 81 Student Edition. Descriptive statistics (mean; median; SEM; s.d.; 95% CI; proportions, etc., as applicable) were calculated for all relevant parameters. Comparison was done between survivors and nonsurvivors, and between horses with FB in the small colon and the large colon. Fisher exact test was used to compare proportional data, whereas continuous data were analysed with nonparametric tests; either Wilcoxon rank sum test (for two categories) or with Kruskal-Wallis One-Way ANOVA (for ≥3 categories). Differences were considered significant at a value of P≤0.05.


Fig 1: The enterotomy site chosen to remove the foreign body (excluding the pelvic flexure) was isolated from the abdomen and a nylon drape was sutured around the incision site using a USP 3-0 polydioxanone suture material.


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