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 © 2010 EVJ Ltd EQUINE VETERINARY EDUCATION / AE / AUGUST 2010 409 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

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