Postoperative Colic Care in Horses: When to Say Whoa

Following colic surgery, some horses experience “reflux,” which describes the abnormal accumulation of gastric fluid in the stomach. Many experts define reflux as the collection of 2 to 8 liters (0.5 to 2 gallons) of gastric fluid when passing a nasogastric tube or the production of 20 or more liters (5 gallons) of gastric fluid over 24 hours.

One study found that when horses with surgically treated large intestinal volvulus develop postoperative reflux (POR), both short- and long-term survival are negatively affected.^* Knowing the poor outcomes associated with POR in these patients helps owners make difficult end-of-life decisions for their hospitalized horses.

“POR typically occurs following surgery for small intestinal disease; however, it can happen following any intestinal procedure, including horses undergoing surgical correction of large intestinal volvulus, a condition in which the large intestine twists and causes an obstruction,” explained Catherine Whitehouse, M.S., a Kentucky Equine Research advisor.

 After reviewing medical records from 128 horses undergoing colic surgery for large colon volvulus, veterinarians found 23 had POR. Only 44% (10) of these horses survived to hospital discharge, which was significantly lower than the 95% survival for horses without POR.

More specifically, only 11% of horses in the POR group were alive three years postoperatively, which was significantly less than the 61% of horses still alive in the group without POR.

“The authors suggested that ileus, a lack of intestinal motility, may contribute to POR. In turn, ileus can be triggered by bowel distension, surgical manipulation, inflammation in the abdominal cavity, or even recurrence of colonic displacement or volvulus post-surgically,” shared Whitehouse.

This was the first study to report the association between POR and survival in horses following large intestinal volvulus. In terms of clinical relevance, the veterinary surgeons noted, “Clinical decisions can be made to discontinue treatment of POR cases sooner due to a more guarded prognosis if desired by the client, and this allows them to make a more informed decision…as continued treatment in the light of a poor prognosis may cause the horse undue suffering.”

Previous research suggests that meal feeding may predispose horses to colic, specifically feeding two large meals of concentrates instead of splitting those into four or even six meals daily.^**

Further, shifts in the microbiome may also predispose horses to colic.

According to Whitehouse, providing horses small, frequent meals; ensuring concentrate meals contain no more than 2-4 g starch per kg body weight; making all feed changes gradually; maintaining water intake and electrolyte balance; and providing adequate amounts and quality forage all help maintain a healthy gut.

During diet transitions, such as hay to pasture or old batch to new batch of hay, it is important to adapt both the horse and their gastrointestinal tract to the new diet.

“Differences in nutrient composition, physical form, and digestibility between forages and feeds can have a significant impact on the digestive tract and overall digestion, which often goes unnoticed. Gradual diet changes allow the gastrointestinal tract to adapt in a coordinated manner. Even when implementing a gradual change protocol, certain horses benefit from additional digestive support during the changeover, such as a hindgut buffer to help stabilize the hindgut environment and changes in fermentation,” Whitehouse explained.

 ^*Watrobska, N., R. Gough, G. Hallowell, S. Haugaard, and K. McGovern. 2024. Factors associated with development of post-operative reflux in horses with large colon volvulus and association with complications and outcomes. Equine Veterinary Journal:14095.

 ^**Blikslager, A.T. 2019. Colic prevention to avoid colic surgery: A surgeon’s perspective. Journal of Equine Veterinary Science 76:1-5.