Nutrition for Horses with Small Intestinal Colic

Small intestinal colic can result from gas or fluid distension, obstruction of the small intestine (ileal impaction or roundworms), or twisting of the gut (small intestinal volvulus or pedunculated lipoma in old horses).

In general, small intestinal colics are more worrisome than large intestinal colics. The usual hallmarks of small intestinal colic are elevated heart rate (can be 80 beats per minute or more; normal heart rate is 28-40 beats per minute), gastric reflux when a nasogastric tube is passed into the stomach, and severe pain that is difficult to relieve. Despite the intense pain, the horse often becomes comfortable when the gastrointestinal tract is decompressed with nasogastric siphonage.

Impactions are dry masses of feed material that lodge in the intestine and occlude it. The intestine often spasms, which further squeezes water from the impaction and produces more pain. Fluid accumulates ahead of the impaction and distends the gut.

In the southern United States, ileal impaction is a frequent diagnosis of small intestinal colic because coastal bermudagrass is a readily available forage. Coastal bermudagrass hay has a high fiber content compared to most other forages and is more likely to cause impactions, especially in dehydrated horses. Tapeworm infections and thickening of the muscular layer of the ileum (muscular hypertrophy) in some older horses also predispose horses to ileal impaction.

The vast majority of colic episodes in horses respond well with passage of a nasogastric tube to relieve gas or fluid accumulation, administration of drugs for pain (flunixin, butorphanol, etc.), and potentially laxatives (mineral oil). Colicky horses that remain painful despite aggressive therapy require exploratory surgery to diagnose and correct the cause of abdominal pain. Occasionally, a segment of gut may be so severely damaged that it must be removed and the two healthy ends sewn back together (resection and anastomosis), or some sort of gastrointestinal bypass has to be performed. Up to half of the small intestine can be removed without any adverse effects.

Horses that responded well to routine medical therapy for colic are usually best managed with an additional 2-3 days of dietary modification. Whenever colic occurs, it is useful to review any changes in the horse’s management that may have led to colic, such as cold weather that may have decreased water intake or a change in hay or concentrate feeding (different source or an increased amount). Fasting for 12-24 hours is a good practice to decrease the amount of feed material in the horse’s intestinal tract and allow the gut to rest.

Horses can be offered small, frequent drinks of water to maintain hydration. Most veterinarians will recommend some period of feed restriction and decreased concentrate feeding for 1-2 days after a colic episode. Short hand-grazing sessions (5-15 minutes) are excellent to allow some feed intake, and walking generally promotes movement of feed through the intestine. Many veterinarians recommend that the horse receive only half of its normal concentrate diet for the first day after colic. Refeeding the horse with several frequent (every 4-6 hours) small meals for 1-2 days gradually transitions the horse back onto full feed. If hay is restricted, it can be sprinkled throughout the horse’s stall so that it takes the horse longer to eat and this simulates grazing.

Horses that have had surgery are more complicated to refeed.  The extent of the surgery usually dictates how soon the horse eats and diet composition. No surgical case is exactly the same, and feeding recommendations will vary based on the lesion identified at surgery, whether a resection and anastomosis or bypass procedure was required, and surgeon experience and opinion. Healthy adult horses can tolerate many days of feed deprivation as long as they are kept hydrated. Horses that have had a resection and anastomosis or any type of gastrointestinal bypass will require a longer period of fasting and a more gradual return to full feeding. Initially, the strength of the surgical repair depends solely upon the suture material. The repair site strengthens gradually as intestinal healing occurs. For this reason, most surgeons will completely fast the horse for 2 days if a bypass, resection, or anastomosis was performed before a gradual return to feed. If no gut was removed and the intestine appeared fairly healthy, then the horse may be fed as it would be after a nonsurgical colic.

It is important to avoid bulk in the intestine for several days to ease strain on the intestinal repair site and to allow the best chance for a strong and healthy return to gut function. Horses that have had small intestinal surgery benefit the most from small and frequent meals for several days postoperatively. Regardless, it is important to not rush the horse back onto feed so the gut has time to rest and heal. Access to fresh grass is better than hay to avoid excessive roughage.