Horses undergoing surgery for omental [epiploic] foramen entrapment: a retrospective study of 145 cases (2008-2016) Word count: 13.540 Michaël Swagemakers Student number: 00906879 Supervisor: ProF. Dr. Ann Martens Supervisor: Dr. Thomas van Bergen A dissertation submitted to Ghent University in partial FulFilment oF the requirements For the degree oF Master oF Veterinary Medicine Academic year: 2017 - 2018 Ghent University, its employees and/or students, give no warranty that the information provided in this thesis is accurate or exhaustive, nor that the content of this thesis will not constitute or result in any infringement of third-party rights. Ghent University, its employees and/or students do not accept any liability or responsibility for any use which may be made of the content or information given in the thesis, nor for any reliance which may be placed on any advice or information provided in this thesis. ©2018 Michaël Swagemakers Index 1. Abstract.......................................................................................................................................... 4 Samenvatting ................................................................................................................................ 4 2. Introduction ................................................................................................................................... 5 3. Literature study.............................................................................................................................. 6 3.1 Anatomy oF the omental Foramen and the omental vestibule ....................................................... 6 3.2 Occurrence ................................................................................................................................... 6 3.3 Risk Factors ................................................................................................................................... 7 3.4 Pathophysiology .................................................................................................................. 8 3.5 Diagnosis ............................................................................................................................ 9 3.6 Treatment ........................................................................................................................ 11 3.7 Prognosis ......................................................................................................................... 12 4. Retrospective study ..................................................................................................................... 13 4.1 Materials and methods ............................................................................................................... 13 4.2 Results ........................................................................................................................................ 14 5. Discussion .................................................................................................................................... 18 References ....................................................................................................................................... 21 Supplementary information items ................................................................................................... 26 ©2018 Michaël Swagemakers 1. Abstract The aim oF this thesis is to document and analyze perioperative data, survival to and aFter discharge, and variables associated with survival of epiploic foramen entrapment (EFE) surgeries in a retrospective study oF 145 horses that underwent surgery For EFE at the Faculty oF Veterinary Medicine, Ghent University, Belgium between March 2008 and December 2016. Pre-, intra- and postoperative data were obtained. Post-operative process was assessed by Follow-up telephone calls with the owner. Factors associated with postoperative ileus (POI), relaparotomy, hospital discharge, colic aFter hospital discharge and survival aFter discharge were assessed. The 145 surgeries were performed on 142 horses (recurrence-rate 3%). Warmblood horses represented 85% oF the horses that underwent surgery and 62% oF the patients were geldings. Windsucking/crib-biting was confirmed in 60% oF these horses. In 100% oF cases leFt-to-right entrapment occurred. In 74% oF cases ileal involvement was recorded. Uncontrollable intraoperative hemorrhage was encountered in 6% oF surgeries. One hundred and seven horses (74%) recovered From surgery. High morbidity and mortality associated with EFE were demonstrated. Survival to discharge of all horses undergoing surgery was 48% and survival to discharge oF all horses recovering From surgery was 65%. Median survival oF discharged horses was in excess oF 3193 days. Statistical analysis on the 145 surgeries demonstrated that a resection perFormed predisposed horses For POI and that horses undergoing jejunoileostomy were more likely to develop POI compared to horses undergoing jejunojejunostomy. Horses that developed POI were less likely to be discharged and horses that underwent resection had shorter liFe expectations aFter hospital discharge. Samenvatting De bedoeling van deze thesis is om data omtrent de operatie, opvolging van de patiënt en de variabelen die geassocieerd zijn met het overleven van een “epiploic Foramen entrapment” (EFE), te documenteren en te analyseren. Door middel van een retrospectieve studie is er onderzoek gedaan naar 145 paarden die tussen maart 2008 en december 2016 chirurgisch zijn behandeld voor een EFE aan de Faculteit Diergeneeskunde te Gent. Er zijn hierbij pre-, intra en postoperatieve data verzameld. PostoperatieF bestond dit uit opvolging van de patiënten aan de hand van teleFoongesprekken met de betreFFende eigenaren. De nadruk van dit onderzoek lag op het verzamelen van de volgende gegevens: factoren die geassocieerd zijn met postoperatieve ileus (POI), re-laparotomie, ontslag uit de kliniek, koliek na ontslag en de overleving van de patiënt na het ontslag. Er zijn in totaal 145 operaties uitgevoerd op 142 paarden (3% recidieven). De patiënten werden voor 85% vertegenwoordigd door warmbloedpaarden en voor 62% door ruinen. Daarnaast werd in 60% van de gevallen bevestigd dat de patiënt een luchtzuiger of kribbebijter was. Bij 100% van de patiënten is een beknelling van links naar rechts vastgesteld en in 74% van de gedocumenteerde operaties was het ileum betrokken. In 6% van alle operaties ondervonden de chirurgen oncontroleerbare intra- operatieve bloedingen. 107 paarden (74%) hebben de operaties overleeFd. Een hoge morbiditeit alsook een hoge mortaliteit, geassocieerd met EFE, is vastgesteld. 48% van de voor operatie aangeboden paarden konden succesvol worden ontslagen uit de kliniek, terwijl dit percentage voor de groep paarden die de operatie overleeFden bij 65% lag. De mediaan van het overleven van de patiënten na ontslag uitgedrukt in aantal dagen, bedraagt 3193. Uit de statistische analyse van de 145 uitgevoerde operaties bleek dat darmresectie de kans op het ontwikkelen van POI vergroot, en dat de kans op POI bij een uitgevoerde jejuno-ileostomie hoger was dan bij een jejuno-jejunostomie. Ook kon worden geconcludeerd dat paarden waar POI is vastgesteld minder kans maakten om te worden ontslagen uit de kliniek en dat paarden, waarbij een darmresectie moest worden uitgevoerd, een kleinere overlevingskans hadden na ontslag. ©2018 Michaël Swagemakers 4 2. Introduction The omental [epiploic] foramen (Foramen omentale [epiploicum]) is a slit-like opening oF about Four to six cm between the abdominal cavity and the omental vestibule (vestibulum bursae omentalis) oF the omental sac (Archer et al., 2004b). In human literature the omental Foramen is called “Winslow foramen”, named after Jacques-Bénigne Winslow (1669-1769) who First described this inner structure (Bellary et al., 2012). Despite the preFerence for “omental foramen” in veterinary anatomical nomenclature, the term “epiploic Foramen” is most commonly used amongst equine clinicians. ThereFore, it was decided to use “epiploic Foramen” throughout tis text. Strangulation oF intestines through the epiploic Foramen (epiploic Foramen entrapment (EFE)) is a life- threatening condition in horses, necessitating surgical intervention (Wheat, 1975). It is Found in about 1,7% to 6,9% oF the surgical colic population (Kilcoyne et al., 2016; Steenhaut et al., 2001). Archer et al. (2004b, 2008a) identified an association between crib-biting/wind-sucking and EFE and mention this oral stereotypic behavior as an important factor increasing the risk to the development oF EFE. Preoperative diagnosis oF EFE can only be suggestive, based on ultrasonographic detection oF distended small intestinal loops with a thickened wall at the level of the right cranial abdomen, whereas a definite diagnosis can only be made during surgery (Klohnen et al., 1996; Scharner et al., 2002; Freeman, 2002). Proudman et al. (2002a, 2002b, 2005) associated epiploic Foramen entrapment with a high morbidity and mortality. In previous studies, short-term survival (survival to hospital discharge) of horses that successfully recovered after surgery for EFE, ranged between 77 and 95% (Freeman and SchaeFFer, 2005; Archer et al., 2011). Ileal involvement consistently seems to occur in about two-thirds oF the reported cases (Edwards, 1981; Vasey, 1988; Engelbert et al., 1993; Vachon and Fischer, 1995; Archer et al., 2004b; Freeman and SchaeFFer, 2005; Kilcoyne et al., 2016) and in the vast majority