Cecal impaction in horses (Proceedings)

Primary cecal impactions

In horses with primary cecal impactions, there is a gradual onset of abdominal pain similar to the development of a large colon impaction. The typical time course is 5-7-days. During this time, veterinarians may use treatments for impactions, such as intravenous administration of analgesics and nasogastric administration of laxatives such as mineral oil, dioctyl sodium sulfocuccinae (DSS) or magnesium sulphate (Epsom salts). However, the crucial aspect of management is to differentiate cecal impactions from large colon impactions. This is because cecal impactions have a propensity to rupture before the development of severe abdominal pain or systemic evidence of shock, and therefore are best referred as early as possible. The way to differentiate cecal impactions from large colon impactions is by rectal palpation. Although the cecum will always be on the right side of the abdomen, large colon impactions can shift from left side of the abdomen to the right side of the abdomen, making this finding difficult to interpret. However, the cecum is attached to the dorsal body wall by its mesentery, whereas the large colon is not attached to the body wall at this location. Therefore, the dorsal surface of a right-sided impaction should be carefully palpated to determine if it is attached to the dorsal body wall. This is not always possible to determine, but can be palpated in approximately 90% of presented cases. If the impacted viscus is attached to the dorsal body wall, it is best to assume it is a cecal impaction and offer the client referral. At the referral center, additional medical therapy may be used, including intravenous fluids. However, in this author's opinion, it is best to take these horses to surgery as it is difficult to determine the full extent of the impaction and the integrity of the cecal wall from rectal palpation.

Secondary cecal impactions

Secondary cecal impactions are more difficult to detect because they are most frequently noted in postoperative patients. These horses may display depression and decreased fecal output that may be attributed to the operative procedure rather than colic. By the time horses with secondary cecal impactions show noticeable signs of colic, the cecum is typically close to rupture. In some cases, there will be no signs of impending rupture. Therefore, all horses that undergo surgeries where considerable postoperative pain may develop should have feed intake and manure production closely monitored. Studies have shown that horses that produce 3 or less piles of manure on a daily basis are at risk of impaction, regardless of perioperative feeding regime. Such a finding should prompt rectal palpation so that an impaction is not missed. The finding of a cecal impaction should prompt surgical exploration of the abdomen.

Pain control in horses that have undergone surgery should be managed aggressively. Although the non-steroidal anti-inflammatory drug (NSAID) phenylbutazone has been implicated in the pathogenesis of cecal impaction, this author's opinion is to aggressively treat pain, including the use of NSAIDs. The full labeled dose of NSAIDs should be administered pre and postoperative if deemed necessary. In addition, opiates such as butorphanol, preferably given as a constant rate infusion, can augment pain control. Although opiates slow intestinal motility, this has not been shown to outweigh the benefit of butorphanol when treating postoperative pain. Veterinarians should be aware that postoperative pain is not always readily detectable. Subtle signs such as depression, standing toward the back of the stall, and failure to show interest in other horses or people in the hospital should be taken into account.

Surgical procedures for cecal impaction

Horses with cecal impactions are surgically managed much like other colic patients. The cecum can be readily found via a midline incision, and the cecum should be evacuated Fig. 1). This is best accomplished from the left side of the horse with the cecal tip facing toward the left flank. During cecal evacuation, surgeons must take care to empty the cupula and base of the cecum as well as the body of the cecum as a great deal of cecal contents can be contained within the dorsal sections of the cecum, and this region is deep within the abdomen and not always readily distinguished from the colon. Once the cecum has been evacuated, the surgeon next needs to make as to make a decision as to whether the cecum should be surgically bypassed. This is because is some cases, the cecum becomes dysfunctional, and will re-fill with ingesta. Although this occurs in a small percentage of the horses presented, it is presently no possible to know which horses require bypass regardless of the type of cecal impaction they have. Therefore, this author's approach is to perform a cecal bypass procure in all cases of cecal impaction where there is any doubt as to the ability of the cecum to empty. A conversation with the owner prior to cecal bypass while the horse is still under surgery is very helpful because this surgery increases the expense and time of the surgery. It is also a valid approach for surgeons to make a clinical decision as to which cases require cecal bypass, because although there are no clear-cut criteria about which horses need a bypass procedure, a number of experienced surgeons have had good success making this decision. The simplest and most effective method to bypass the cecum is to do a complete ileocolic bypass during which the ileum is transected, oversewn, and connected to the right dorsal colon in side-to-side fashion. The latter is best accomplished with a stapling instrument that can transect and staple at the same time.

Prognosis

The prognosis is guarded until the integrity of the cecum has been determined. If there is no evidence of rupture or devitalized intestine, the prognosis can be upgraded to fair. For example, in a recent report, 7 of 9 horses for which cecal impaction was treated by typhlotomy and ileo- or jejunocolostomy lived long-term. However, a separate report indicated that all horses with cecal impaction secondary to another disease process had cecal rupture without any signs of impending rupture and therefore carried a poor prognosis.