Post-surgical management after enterotomy

Return an animal to its stall after having “fixed” a colic problem is only the beginning of the journey. Broadly speaking, 80 % of horses undergoing colic surgery survive to hospital discharge. In the long-term (1 yr or more) survival rates range from 34-90%, depending on age and location of lesion. The post-operative phase is critical and yet there is little “glory” to be had at this point. This is also the point at which the client is ever-present, thus the specter of a lawsuit looms in cases with unsuccessful outcomes. The expectations are that the horse will be free of colic/pain; that it will be able to manage its fluid and nutritional intake; that the gastrointestinal tract will function normally; and the catheter and incision will remain infection free. The outcome however, may be very different.

Fluid and Nutritional Management

Fluid therapy is a massive topic that has the potential to directly influence GI motility. Overall, however it is important to deliver sufficient fluids to address any surgical, or trauma-related, loss as well as ongoing maintenance. In most cases 1 liter per hour is necessary (in temperate climates) to address normal needs in a 500kg horse. These can be delivered intravenously using a balanced, isotonic solution, or parenterally via a stomach tube. For post-enterotomy fluid management, either the horse is not administered any additional fluid (large colon enterotomy at the pelvic flexure) or an appropriate, electrolyte managed fluid (calcium, potassium or magnesium enriched). The benefit of fluids administered per os (via a stomach tube) is that no special or expensive materials are needed, and the fluid delivered induces a gastrocolic reflex, which may actually assist in developing, or improving, large colon motility.

Post-operative nutrition is a very important aspect of the post-operative colic patient. It will not be discussed in this lecture as it is covered elsewhere

Post-operative ileus (POI)

POI has a prevalence ranging from 10-56%. Risk factors have been reported as being high packed cell volume (PCV) and heart rate, longer durations of surgery and anesthesia, and small intestinal involvement. In one study there were no incidences of POI with jejunojejunostomies, but increased risk after jejunocecostomies. There is also one study suggesting that a pelvic flexure enterotomy may reduce the risk of POI but that is not a consistent finding in the literature.

Re-laparotomy & Adhesion formation

Post-operative pain with, or without gastrointestinal ileus, is a reason to re-operate a colic. If there is a need to go back to surgery, it is better to re-operate early. However, it is important to realize that approximately 50% of horses who are put back on the table are euthanased during the second surgery. There is also a much higher risk of incisional infection and subsequent herniation with a second surgery in the post-operative period.

The development of abdominal adhesions post-celiotomy is well documented in humans as well as in domestic animals. They are a cause of significant post-operative morbidity, especially in small intestinal surgery. The majority of adhesions pose no clinical threat, however their prevalence accounts for adhesions being the most common cause of small intestinal obstruction in humans (26-64%), some of which will necessitate a repeat surgery and adhesionolysis. In a human post-mortem study 67% of patients had abdominal adhesions after a single celiotomy; whereas 97% of those people having more than one abdominal surgery had adhesions.

In the horse, between 6 and 26% of animals undergoing abdominal surgery will develop adhesions, which may result in small intestinal obstruction, internal herniation and strangulation post-surgery. These may result in an acute, emergency situation (usually within the first 60 days post-surgery) or recurrent episodes of abdominal pain in the post-operative patient. Foals, similar to human children, are considered at increased risk of developing post-operative abdominal adhesions (33%).

Unfortunately, the presence of adhesions can only be made at a second surgery (laparotomy or laparoscopy) or at post-mortem and thus the true incidence is unknown. The majority of adhesions are likely asymptomatic however it is not known how many or whether a single adhesion in a particular anatomical location will be a cause for concern. Common sites of adhesion formation in the horse are between the tip of the cecum and the ventral body wall and between loops of small intestine.

Overall, the myriad products and multiple interventional strategies aimed at reducing adhesion formation in the horse (specifically the foal) highlight a lack of basic pathophysiological knowledge that needs to be addressed before yet another “wonder product” is tested.

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