Clinical Commentary the Enigma of Post Operative Recurrent Colic: Challenges with Diagnosis and Management S

408 EQUINE VETERINARY EDUCATION / AE / AUGUST 2010

Clinical Commentary The enigma of post operative recurrent colic: Challenges with diagnosis and management S. Hart* and L. L. Southwood University of Pennsylvania, School of Veterinary Medicine, Department of Clinical Studies, USA.

The importance of post operative recurrent of early referral and surgical intervention not only in the colic and possible causes prevention of short-term but also long-term complications including problems with adhesion formation and recurrent Recurrent colic is a frustrating problem to manage in colic. horses, particularly following abdominal surgery for On the other hand, gas colic and recurrence of colonic gastrointestinal disease. Possible causes of post operative displacement or volvulus is the most common cause of recurrent colic are shown in Table 1. Colic was the most post operative recurrent colic for horses with large colon frequently reported short- and long-term complication disease. Recurrence rates for nephrosplenic entrapment of following abdominal surgery, with 30–35% of horses having the colon were most recently reported to be 8% (Hardy at least one episode of colic following hospital discharge et al. 2000) and 15% for right dorsal colon displacement (Proudman et al. 2002; Mair and Smith 2005). Importantly, and volvulus (Hance and Embertson 1992). Horses with most signs of colic occurred within the first 100 days of right dorsal displacement of the large colon were surgery and only 5% of horses had more than 3 colic significantly more likely to experience recurrent episodes of episodes (Proudman et al. 2002). While at an initial glance colic requiring veterinary intervention post operatively these numbers may be somewhat of a deterrent to (42%) compared to other types of displacement, recommending colic surgery, it is important to recognise particularly nephrosplenic entrapment (8%) (Smith and that 95% of horses had either none or only one episode of Mair 2010). Reasons for this disparity are unknown. colic after surgery! Reasons for post operative recurrent Surprisingly, there was only one horse in the latter study that colic should be identified so that every effort toward had recurrent episodes of colic prior to the one prevention is made. The role of recurrent colic prior to the necessitating surgery. In another study, horses that had episode requiring surgery also needs consideration when experienced signs of colic prior to the episode evaluating horses with signs of colic following surgery and necessitating surgery for large colon displacement or deciding on a management strategy. volvulus had a higher occurrence of colic post operatively Reasons for post operative recurrent colic are different compared to horses with no prior history of colic for horses with small vs. large intestinal lesions. Horses with (Southwood 2006). These findings suggested that there small intestinal lesions, particularly necessitating resection may be management factors or underlying motility and anastomosis, reportedly had a higher occurrence of disorders associated with colic in some of these patients. colic after surgery than horses with large intestinal Motility disorders may be associated with reduced lesions (Mair and Smith 2005). Intra-abdominal adhesion myenteric plexus and neuron density. Schusser and White formation was an important reason for recurrent colic (1997) found that horses with chronic colonic obstruction following small intestinal surgery (Mair and Smith 2005). (>24 h duration) or with previous obstruction had Some of the factors associated with colic and adhesion significantly lower neuron density than normal horses in the formation included packed cell volume, total plasma pelvic flexure. Myenteric plexus and neuron density in horses protein, serosanguinous peritoneal fluid, resection and with strangulating large colon volvulus was significantly less anastomosis, and the development of post operative ileus than normal and horses with colon strangulation that and the need for repeat laparotomy (Mair and Smith 2005; survived had significantly greater neuron density than Proudman et al. 2005). Most of these factors are horses with colon strangulation that died. Horses with a reflection of lesion severity and the extent of chronic recurrent caecal impactions also had lower linear cardiovascular compromise emphasising the importance neuron densities compared to normal horses (Schusser et al. 2000). While findings suggest an association between lower *Corresponding author email: [email protected] neuron and myenteric plexus density and colonic or caecal

TABLE 1: Possible causes of recurrent colic for post operative colic TABLE 2: Recognised risk factors for chronic or recurrent colic cases Specifically for post Intestinal adhesions General considerations operative colic cases Impaction/obstruction Colonic displacement/volvulus Age (>8–10 years old) Previous abdominal surgery Stricture or stenosis at an anastomosis Geldings Small intestinal lesions Enteritis/colitis including right dorsal colitis Arabian breed Right dorsal displacement of Peritonitis large colon Gastric ulceration Less exposure to pasture/hours >360° large colon volvulus Lymphosarcoma or other neoplasia spent in a stable Liver disease Feeding coastal grass hay Post operative ileus Intussusception Feeding >50% alfalfa hay Resection of intestine Enterolithiasis Feeding large amounts Re-laparotomy Abnormal mesenteric attachments concentrates Mesenteric rents Recent change in diet, activity Incisional complications Diaphragmatic hernia level and stabling conditions Abscessation Travel within the preceding 24 h Diverticula formation Previous episodes of colic Equine dysautonomia (grass sickness) Infrequent dental examination Nongastrointestinal (urogenital, pleuropneumonia) Absence of administration of an ivermectin or moxidectin-based (Archer 2009). anthelmintic within the previous 12 months Windsucking/crib-biting dysfunction, the methodology neglected the areal distribution (Freytag et al. 2008) and further studies are (Cohen et al. 1995; Cohen and Peloso 1996; Hudson et al. 2001; warranted to improve our understanding of the relationship Hillyer et al. 2002; Proudman et al. 2002; Mair and Smith 2005). between the enteric nervous system and colic. The possibility that a problem, such as an enterolith or abdominal surgery for a nephrosplenic entrapment (left neoplastic disease, was not identified at the initial surgery dorsal displacement) of the large colon. The authors relied should always be taken into consideration when primarily on abdominal palpation per rectum to obtain a evaluating a horse with post operative recurrent colic diagnosis of impaction of the ascending and descending (Table 1). colon, colonic distention and as described in the In the accompanying article, Torre et al. (2010) present discussion, recurrent colonic displacement. While a case of chronic, recurrent colic in a mare that was palpation per rectum can be a valuable diagnostic tool, associated with a mesocolon rent following surgical in cases of recurrent colic it probably should be correction of nephrosplenic entrapment of the large complemented with other diagnostic modalities. In colon. This case report raises several important questions particular, the diagnosis of colonic displacement by regarding the investigation and management of cases of palpation per rectum alone can be unreliable. Abdominal recurrent colic when encountered post operatively. ultrasonographic examination, peritoneal fluid analysis, gastroscopy, laparoscopy and abdominal radiography Diagnostic approach to the horse with are all diagnostics that should be considered to investigate recurrent colic post operatively post operative recurrent colic and can be used to complement palpation per rectum findings. A key factor in the initial diagnostic approach to the horse Abdominal ultrasonographic examination can be with post operative recurrent colic is a thorough, detailed useful, and is often one of the first diagnostic modalities used history to identify potential risk factors (Table 2). Further in the investigation of recurrent colic post operatively. Both investigation of recurrent colic should be tailored to the transabdominal and per rectum examinations can be individual horse as well as the needs and means of the performed, and with the newer, more powerful machines, owner; some owners may consider occasional episodes of greater detail and depth penetration is available for mild colic as acceptable provided the horse responds to evaluation of the abdomen. Ultrasonographic examination administration of an oral nonsteroidal anti-inflammatory can be used to identify the presence of: abdominal drug such as flunixin meglumine. However, these owners adhesions; intestinal thickening or dilation; intra-abdominal should understand that these horses are at significantly abscesses and haematomas that may arise from the increased risk of continuing to colic (Hillyer et al. 2002) and mesentery, an anastomosis or enterotomy; nephrosplenic have a significantly higher death rate (Mair and Smith entrapment of the large colon; and right dorsal 2005) compared to horses that do not have recurrent displacements of the colon where the colon is rotated 180° problems with colic. Therefore, an attempt to determine resulting in visibility of the vessels on the visceral side of the the cause is indicated in particularly problematic cases. colon and abnormal positioning of the dorsal and ventral Torre et al. (2010) report multiple episodes of colic over colons. Additionally, increased volume or abnormally a period of 63 months (more than 5 years) after a first appearing peritoneal fluid is easily seen, from which a

sample can be collected for cytological evaluation and Closure of the mesenteric rent as performed by Torre et al. bacterial culture and sensitivity testing, if indicated. (2010) is indeed warranted, and is recommended when a Laparoscopic abdominal exploration with the horse mesenteric rent is encountered. A major concern, standing or anaesthetised and in dorsal recumbency may however, is the diagnosis of multiple episodes of colic be another useful tool to investigate recurrent colic. presumably associated with the ascending colon, which Laparoscopy may be useful to diagnose and treat may be due to altered motility (Schusser and White 1997; nephrosplenic entrapment of the large colon (Busschers Fintl et al. 2004). A valid concern raised by Torre et al. et al. 2007), mesenteric rents (Sutter and Hardy 2004) and (2010) is the low survival rate typically associated with large abdominal adhesions (Rijkenhuizen and Dijk 2002). colon resection, which appeared to be a determining Laparoscopic-guided biopsies of intestine and other factor in the authors not performing the procedure. viscera can also be performed (Ragle 2002; Bracamonte Despite this, large colon resection is a valid treatment et al. 2008). Although laparoscopy has been reported to option in the management of recurrent displacement have low specificity in chronic or recurrent colic (Walmsley associated with the large colon. In a recent publication it 1999), it can be useful in certain cases. was reported that horses in which a large colon resection Abdominal radiographic examination and gastroscopy was performed had a significantly higher survival rate if can also be performed. These diagnostics may have lower there was nonstrangulating large colon disease (78% yield; however, enteroliths, sand impactions and gastric short-term survival) vs. strangulating disease (47% ulceration can all result in recurrent colic. Enteroliths and short-term survival) (Driscoll et al. 2008). In cases such as sand accumulations are more likely to be a cause of this, where a horse has a history of recurrent colic recurrent colic in horses that have not recently had associated with the large colon and the colon appears abdominal surgery; however, it is important to recognise healthy at surgery, a large colon resection may almost be that enteroliths and smaller sand accumulations can be performed as a ‘semi-elective’ procedure. This can be missed during abdominal exploration or can recur post performed as a preventive measure, to avoid the horse operatively. Gastric ulceration has a high prevalence in presenting in the future with a nonviable colon and a certain populations of horses and can result in recurrent significantly poorer chance of survival, or worse, not having colic. Stress, intermittent feeding, stall confinement, illness a repeat surgical option. Colon resection, however, does and nonsteroidal anti-inflammatory administration are all not prevent problems such as right dorsal colon impaction recognised risk factors (Videla and Andrews 2009). or tympanic colic. Although gastroscopy is relatively simple to perform,a3m Other treatment options include colopexy, which is not video endoscope is required. Gastroscopy can also be recommended by many surgeons in athletic animals due used to diagnose other types of recurrent colic involving to the risk of rupture (Hance and Embertson 1992) or the proximal gastrointestinal tract such as gastric neoplasia laparoscopic closure of the nephrosplenic space if (Taylor et al. 2009) and other obstructions (Kellam et al. recurrent nephrosplenic entrapment of the large colon is 2000; Buchanan et al. 2006). diagnosed. The primary concern with laparoscopic Repeat laparotomy should be considered as a closure of the nephrosplenic space is that it does not diagnostic (and optimistically therapeutic) tool if the prevent development of other large colon displacements recurrent colic is severe or persistent as in the case and may therefore not reduce the risk of recurrent colic described by Torre et al. (2010) particularly when other post operatively (Farstvedt and Hendrickson 2005; Rocken diagnostic procedures have been unrewarding. et al. 2005). In any horse with recurrent colic, particularly post Management of post operative operatively, management factors should be addressed. recurrent colic Horses with recurrent colic post operatively may be candidates for dietary changes, primarily introducing a The diagnosis of recurrent ascending colonic distention ‘low bulk’ diet by restricting hay intake, providing free and suspected displacement in this mare also raises an access to pasture, and using a complete pelleted feed. important question regarding the origin of the mesenteric Ensuring the horse is on an appropriate de-worming rent and its role in the signs of post operative recurrent schedule including ivermectin and praziquantal-based colic. It is difficult to determine in this case whether the anthelmintics and has regular dental examinations is also presence of a mesenteric rent resulted in recurrent colonic important. problems or whether recurrent impaction and Recurrent colic post operatively can be difficult to displacement resulted in a mesenteric rent. The association manage both diagnostically for the equine veterinarian between the rent and descending colon impaction is also and emotionally for the owner. Although finding answers difficult to understand. While this may seem somewhat can sometimes be difficult, obtaining a thorough history, academic, it is important to consider with respect to the and utilising diagnostics such as abdominal long-term prognosis and management of this case. ultrasonography and laparoscopy can help to put the A universal debate raised by this case report is the pieces of the puzzle together. Clinical and basic science question of whether or not to resect the large colon. research is necessary to develop our understanding of the

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