Clinical Considerations of Intestinal Entrapment Through the Gastrosplenic Ligament in the Horse K

EQUINE VETERINARY EDUCATION / AE / JANUARY 2013 21

Clinical Commentary Clinical considerations of intestinal entrapment through the gastrosplenic ligament in the horse K. F. Ortved Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, New York, USA. Corresponding author email: [email protected]

The gastrosplenic ligament (GSL) is rarely involved in intestinal common and although small intestinal incarceration is the accidents and consequently is infrequently mentioned in the most common form of GSL entrapment, net reflux on equine veterinary literature. The vast majority of reports of the presentation is not common. Jenei et al. (2007) suggested GSL involve small intestinal incarceration through a rent that this may be due to the distal small intestine becoming (Yovich et al. 1985; Mariën and Steenhaut 1998; Jenei entrapped most frequently, recent gastric decompression, et al. 2007; Hunt et al. 2013) with few reports describing dehydration and/or a short duration of entrapment prior to incarceration of other gastrointestinal structures including the presentation. Small intestinal distension may be palpated on small colon (Rhoads and Parks 1999) and large colon (Trostle rectal examination but this does not appear to be a consistent and Markel 1993; Torre 2000). Although there is documentation finding. Transabdominal ultrasonography is a useful diagnostic of strangulation of the jejunum alone, jejunum and ileum, or tool for confirming small intestinal dilation (Beccati et al. 2011) ileum alone through rents in the GSL, Jenei et al. (2007) in equine colic. Small intestinal dilation noted in the left reported that GSL entrapment accounted for only 1.5% of all cranioventral abdomen lateral to the spleen may be positively horses undergoing exploratory celiotomy and only 4.6% of correlated with GSL entrapment as suggested by Hunt et al. horses with primary small intestinal lesions. (2013); however, this has yet to be confirmed by a prospective The anatomy of the GSL has been described in detail in study. The vast majority of horses with GSL entrapment have the recent case report by Hunt et al. (2013) in which the increased free peritoneal fluid that is serosanguineous in authors provided in-depth description and images of the GSL nature with elevated nucleated cell counts (3.2–39.0 x109 in situ. Briefly, the GSL is a broad, thin band of omentum cells/l) and total protein (26–42 g/l) concentrations consistent located between the hilus of the spleen and left greater with strangulating gastrointestinal lesions (Yovich et al. 1985; curvature of the stomach. It is continuous with the greater Rhoads and Parks 1999; Jenei et al. 2007; Hunt et al. 2013). omentum ventrally and the gastrophrenic and nephrosplenic Although not reported in cases of GSL entrapment, it ligament dorsally. The ligament is considerably thicker at its is likely that peritoneal fluid would also have elevated lactate dorsal attachment and becomes progressively thinner levels as noted in other strangulating lesions (Latson et al. 2005; ventrally as it joins the greater omentum. The blood supply to Yamout et al. 2011). the GSL is from the left and right gastroepiploic arteries. The All reported cases of small intestinal GSL entrapment gastroepiploic artery is a continuation of the splenic artery have involved variable lengths of devitalised intestine where it exits the tip of the spleen and enters the greater necessitating surgical intervention with resection and omentum. The splenic artery is a branch of the coeliac artery, anastomosis. Incarceration occurs in a caudal to cranial which exits the cranial abdominal aorta. Intestines are direction in all reported cases (Yovich et al. 1985; Mariën and normally located axial and caudal to the GSL. The role of the Steenhaut 1998; Jenei et al. 2007; Hunt et al. 2013). Most case GSL in the horse remains largely unknown but Hunt et al. reports of GSL entrapment suggest that manual traction on the (2013) suggest that it may act as a suspensory apparatus of entrapped bowel is sufficient to reduce the incarceration the stomach and spleen helping to maintain their normal (Yovich et al. 1985); however, some reports have described anatomical position in the abdomen. manual dilation of the rent (Mariën and Steenhaut 1998). The Horses with gastrointestinal entrapment through the GSL GSL has little blood supply therefore, haemorrhage following can present with mild to severe colic signs depending on the manual dilation or partial transection does not appear to be duration and severity of incarceration. All reports of small a major concern. In the case report by Hunt et al. (2012), intestinal incarceration through the GSL have been in mature traction and manual dilation were unsuccessful requiring horses (Yovich et al. 1985; Mariën and Steenhaut 1998; Jenei partial transection of the GSL to the ventral free border. The et al. 2007; Hunt et al. 2013). The largest case series of GSL LigaSure vessel sealing system (LigaSure-8)1 was used to limit entrapment by Jenei et al. (2007) included 16 horses and bleeding during transection by Hunt et al. (2013). Alternatively, reported a median age of 15.5 years (range 8–23 years), ligatures could be placed in the accessible portion of the although Torre (2000) did report a case of incarceration of the ventral GSL during transection. ascending colon in an 8-month-old Thoroughbred colt. A Recurrence of GSL entrapment has not been reported; predilection for geldings has been suggested, although an however, Vachon and Fischer (1995) have described anatomical explanation has not been determined (Tennant reincarceration of small intestine through the epiploic 1975; Jenei et al. 2007). On presentation, most horses are foramen. Rents in the ligament are most commonly not moderately tachycardic, haemoconcentrated with an repaired following reduction of the incarceration. Repair of elevated packed cell volume and variable serum total protein GSL is usually not possible during exploratory celiotomy due to depending on the degree of vascular compromise and poor accessibility. Additionally, the tissue tends to be friable intestinal oedema (Yovich et al. 1985; Rhoads and Parks 1999; and unable to hold sutures. Partial transection of the GSL to the Jenei et al. 2007; Hunt et al. 2013). Intestinal hypomotility is nearest free border can be performed and may prevent

re-entrapment. Transection of the GSL does not appear to repaired and no long-term complications associated with this cause long-term complications; however, Hunt et al. (2013) defect were reported. propose that loss of anatomical support could result in lateral displacement or torsion across the long axis of the Author’s declaration of interests spleen or that small intestine could be displaced lateral to No conflicts of interest have been declared. the spleen. Standing laparoscopic evaluation and repair of the dorsal GSL may be possible; however, based on the current Manufacturer’s address literature, repair does not seem to be indicated as no 1Tyco Health Care UK Ltd, Hampshire, UK. long-term complications have been reported when tears are left open. Moreover, most GSL tears occur in the ventral aspect of the ligament, which is not accessible with standing References laparoscopy. Beccati, F., Pepe, M., Gialletti, R., Cercone, M., Bazzica, C. and Nannarone, S. (2011) Is there a statistical correlation between Rents in the GSL may be associated with trauma or ultrasonographic findings and definitive diagnosis in horses with increased intra-abdominal pressure due to pregnancy, acute abdominal pain? Equine Vet. J. 43, 98-105. dystocia, strenuous exercise and/or severe gastrointestinal Hunt, L., Paterson, E., Sare, H., Kearney, C., McAllister, H. and David, F. distention (Trostle and Markel 1993). Congenital defects (2013) The equine gastrosplenic ligament: anatomy and clinical in the GSL may also occur. The horse described by Hunt considerations. Equine Vet. Educ. 25, 15-20. et al. (2013) had a traumatic event several days prior Jenei, T.M., Garcia-Lopez, J.M., Provost, P.J. and Kirker-Head, C.A. (2007) to presentation; however, direct association with the GSL Surgical management of small intestinal incarceration through the gastrosplenic ligament: 14 cases (1994-2006). J. Am. Vet. Med. entrapment could not be determined. Yovich et al. (1985) Ass. 231, 1221-1224. reported that histopathological examination of the torn Latson, K.M., Nieto, J.E., Beldomenico, P.M. and Snyder, J.R. (2005) ligament in 1/5 horses showed fibrin and haemorrhage Evaluation of peritoneal fluid lactate as a marker of intestinal consistent with a recent tear, while 2/5 horses had ischaemia in equine colic. Equine Vet. J. 37, 342-346. haemorrhage without gross fibrosis. Mariën, T. and Steenhaut, M. (1998) Incarceration of small intestine Hunt et al. (2013) propose that transabdominal through a rent in the gastrosplenic ligament in five horses. Equine ultrasonography may aid in preoperative diagnosis of Vet. Educ. 10, 187-190. GSL entrapment and that this information could be used Rhoads, W.S. and Parks, A.H. (1999) Incarceration of the small colon to vary surgical technique to allow better access to the GSL. through a rent in the gastrosplenic ligament in a pony. J. Am. Vet. Med. Ass. 214, 226-228, 205. Although small intestinal dilation noted in the left cranioventral abdomen lateral to the spleen may be suggestive of GSL Tennant, B. (1975) Intestinal obstruction in the horse: some aspects of differential diagnosis in equine colic. Proc. Am. Ass. Equine Practnrs. entrapment, a confirmed preoperative diagnosis does not 21, 426-438. appear necessary as these horses all present with signs of Torre, F. (2000) Incarceration of the ascending colon in the gastrosplenic a strangulating small intestinal lesion for which surgical ligament in a foal. Equine Vet. Educ. 12, 83-84. intervention is always indicated. Additionally, a standard Trostle, S.S. and Markel, M.D. (1993) Incarceration of the large colon in ventral midline celiotomy provides good access to the entire the gastrosplenic ligament of a horse. J. Am. Vet. Med. Ass. 202, gastrointestinal tract and a confirmed diagnosis of GSL 773-775. entrapment would probably not change the abdominal Vachon, A.M. and Fischer, A.T. (1995) Small intestinal herniation approach. through the epiploic foramen: 53 cases (1987-1993). Equine Vet. J. 27, 373-380. Overall, horses appear to have a good long-term prognosis following surgical correction of GSL entrapment. Jenei et al. Yamout, S.Z., Nieto, J.E., Beldomenico, P.M., Dechant, J.E., Lejeune, S. and Snyder, J.R. (2011) Peritoneal and plasma d-lactate (2007) reported a long-term success rate of 78% following concentrations in horses with colic. Vet. Surg. 40, 817-824. resection and anastomosis of devitalised small intestine. Some of Yovich, J.V., Stashak, T.S. and Bertone, A.L. (1985) Incarceration of small the rents were enlarged to allow reduction but partial transection intestine through rents in the gastrosplenic ligament in the horse. Vet. was not performed in any horse. None of the GSL rents were Surg. 14, 303-306.

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