During a presentation at the 2012 Kentucky Equine Research Conference, held May 17-18 in Lexington, Ky., Amelia Munsterman, DVM, MS, Dipl. ACVS, ACVECC, clinical lecturer in equine critical care medicine and surgery at the Auburn University College of Veterinary Medicine, gave a presentation on feeding horses with or after colic.
The Relationship Between Feeding Choices and Colic
Munsterman first explained that horses evolved to consume small quantities of high fiber, low carbohydrate feeds continuously. Many modern-day feeding techniques, she said, contradict these nutritional needs. Tactics such as stall confinement and large meals, for instance, can lead to digestive upset and colic, she said.
Munsterman also discussed associations between different feed types and colic:
- Pasture: Munsterman said that although horses were designed to consume grass throughout the day, today’s pastures often contain different grasses with high levels of fermentable carbohydrates that can potentially cause seasonal colic. One study she discussed found no decrease in colic risk with turnout, while another case-controlled study she discussed revealed horses not allowed turnout or with a recent reduction in turnout were three times more likely to develop colic than horses allowed ample pasture access. She noted that in the first study, lack of water available in the pasture doubled the colic risk.
- Dried Forage: Hay is a popular forage choice for horses, but Munsterman noted it too has been associated with colic development. One study she discussed showed that consuming large portions of low-quality forage increased the risk of impaction colic, and another revealed that horses consuming round bale hay had a 2.5 times greater risk of colicking. Additionally, she noted, abrupt hay changes have been implicated in colic cases. Finally, she explained that researchers have linked both coastal Bermuda hay and alfalfa hay to colic; the former contributing to ileal impactions (a blockage forming in the small intestine) and the latter creating a dietary tract environment that promotes enterolith (intestinal stone) formation.
- Concentrates: “Carbohydrate-rich feeds, including grains, are the most commonly implicated dietary cause of colic in the horse, likely due to the well-documented influences of this substrate on the flora of the equine gastrointestinal tract,” Munsterman said. Research study results have found several associations between concentrates and colic risk, she said. One found that feeding more than 2.7 kilograms of oats per day increased colic risk, while another identified whole corn as a major risk factor. Studies have yielded conflicting results regarding whether pelleted feeds increase colic risk, but researchers have shown that changes in the concentrate a horse consumes elevates colic risk.
Although research has provided some conflicting results, Munsterman offers proven feeding suggestions to prevent colic:
- Provide a consistent diet, as diet changes increase colic risk;
- Ensure at least 60% of the horse’s diet is forage (hay or pasture), and ensure this amounts to a minimum of 1 to 1.5% of the horse’s body weight per day if weight loss is needed; healthy horses should consume about 2% of their body weight daily;
- Keep concentrate consumption to a minimum, and break concentrate meals into several small servings throughout the day;
- If additional energy is required in the horse’s diet, consider concentrated sources such as vegetable oil, beet pulp, or soy hulls; and
- Make all dietary changes gradually over the course of seven to 10 days.
Feeding After Colic
Munsterman relayed that different types of colic require different post-treatment feeding plans. She outlined several different types of colic and made suggestions for refeeding.
Simple colic cases that resolve quickly and relatively easily are considered uncomplicated. These resolve with medical treatment, and the horse generally recovers in 12 to 24 hours, she said.
In these cases, Munsterman said, feeding can resume as soon as normal gut sounds (borborygmi) and fecal production return. She recommended providing small amounts of good-quality grass hay every four to six hours for the first 12 to 24 hours. The horse’s forage rations can increase and return to normal over 24 to 48 hours if no adverse reactions are noted, she said. She noted the importance of ensuring the horse stays hydrated post-colic. Avoid feeding concentrates for 10 to 14 days post-colic, she said, to avoid any potential gastrointestinal disruption.
She also recommended evaluating the horse’s diet, environment, and feeding schedule to try to identify any predisposing risk factors for colic.
Researchers have shown that inflammation of the small intestines, known as duodenitis-proximal jejunitis (DPJ) or anterior enteritis, often occurs in horses with pasture access, Munsterman said. Treatment for DPJ can be either medical or surgical, depending on the colic’s severity, she said. Both medical and surgical cases have a good prognosis for recovery if treated aggressively and if the disease is “allowed to run its course,” she added.
Horses with DPJ often can’t consume food normally due to ileus (lack of intestinal motility) and resulting gastric reflux, she said. Thus, to avoid excessive protein loss, veterinarians often administer parenteral nutrition (through an intravenous catheter), she said, and continue this until the horse can consume regular food without gastric reflux.
“Enteral feeding can begin once progressive motility is confirmed by a lack of net gastric reflux and ultrasonographic confirmation of small intestinal contractions,” she said. At that point, Munsterman recommended providing hay, complete feed, or alfalfa pellets at 25% of the daily ration, divided into meals every two to four hours. The horse should be able to return to full rations in two to three days, she said.
For these horses, avoid feeding concentrates or grass with high fermentable carbohydrate concentrations, she said, and keep the horse off grain for about two weeks. If the horse needs to regain body condition, consider feeding high-protein forages or adding vegetable oil to the feed, she said.
Small Intestinal Strangulation
Regardless of the cause, veterinarians typically treat this dangerous condition surgically. Munsterman said the small intestine is sensitive to manipulation, so post-operative ileus is a common occurrence.
To prevent or reduce the chances of ileus, Munsterman said some veterinarians have adopted a newly validated practice of offering food to horses as soon as possible after recovering from anesthesia. She outlined one plan described by Freeman et al. of providing water 12 to 18 hours post-operation and then offering handfuls of alfalfa hay at 18 to 24 hours. Build the horse up slowly to 75% of his total feed rations over the next day or two, she said.
If the horse isn’t able to consume food enterally (via the gastrointestinal tract), parenteral nutrition is an option. “It is still unclear as to any benefits of providing parenteral nutrition to surgical colic cases, with the downside of an increase in cost to the client,” Munsterman cautioned. “Based on the lack of clear evidence, most horses are simply held off feed until ileus subsides.”
Veterinarians can often treat ileal impactions medically; however, severe cases might require surgery, Munsterman said. In this event, refeeding practices are similar to those for small intestinal strangulations, she said.
Most ileal impactions resolve within 12 hours, so parenteral nutrition isn’t often required, she said. Feeding can resume once intestinal motility resumes.
Munsterman cautioned that because studies have implicated coastal Bermuda in ileal impaction development, avoid providing recovering horses with this type of forage. Instead, aim for high-quality, first-cutting hay, and ensure sufficient water intake, she said (if Bermuda is the only forage available, Munsterman recommended feeding good-quality, first-cutting). If good-quality hay is not available, owners can substitute pelleted complete feeds, chopped hay, or pasture.
Large Colon Impactions
Veterinarians treat the most common colic cause in horses, large colon impactions (a blockage forming in the large intestine), similarly to ileal impactions. Feed should be withheld during treatment, Munsterman said, but feeding should not be delayed once treatment has resolved.
“Good-quality forages, ideally alfalfa hay, should initially be provided in small amounts four to six times daily, with a gradual increase over 24 to 48 hours to normal rations,” she said. Upon reintroducing feed, she recommended providing free-choice hay to reduce the risk of gastric ulcer development.
Green grass or alfalfa-based diets could provide a laxative effect, she said, and might help prevent recurrence in recovered horses. Additionally, she advised promoting water intake with salt or electrolyte supplementation to prevent impactions.
Veterinarians generally treat sand impactions medically, similar to feed impactions, Munsterman said, but severe cases might necessitate surgical correction.
The key to feeding horses post-sand impaction colic is to remove the animal from the sandy area, if possible. Additional steps include:
- Avoid feeding the horse on the ground, if possible;
- Use large tubs and/or rubber mats to prevent feed from spilling on the ground;
- Avoid using overgrazed pastures; and
- Provide horses with a psyllium supplement for one week, monthly, as a preventive measure.
However, “the most effective method of clearing sand from the gastrointestinal system is to provide 2.5% of body weight per day of hay,” said Munsterman. “The bulk alone is capable of removing almost 95% of ingested sand and was better in a controlled trial than psyllium, mineral oil, or wheat bran.”
Enteroliths and Fecaliths
Enteroliths are intestinal stones are made up of minerals, such as magnesium ammonium phosphate salts, that build up around a foreign object a horse eats but does not digest. Similarly, fecaliths are compacted fecal material in the intestine. Munsterman noted that surgery is the most common treatment for both conditions. Owners should feed post-treatment horses similarly to horses recovering from impactions, she said.
Munsterman noted owners can take preventive nutritional measures post-surgery to try to prevent future stones from forming, including:
- Feed less than 50% alfalfa hay to predisposed horses, as alfalfa’s high protein content has been statistically linked to enterolith formation;
- Wheat bran is also suspected to encourage enterolith formation; however, it has never been linked definitively. Thus, consider limiting wheat bran intake for affected horses;
- Avoid stall confinement for more than half the day, high-protein diets, low-fiber diets, and intermittent meals; and
- Consider monthly psyllium treatments or feeding 2 to 2.5% of the body weight in hay daily to help clear ingesta that could lead to an enterolith or a fecalith.
Ascending Colon Displacement:
Munsterman explained that the ascending colon moves freely in the abdomen, so displacements aren’t uncommon. Medical treatment is possible, however many horses are taken to surgery, she said.
Post-treatment horses should be fed in a similar manner as large colon impactions, she said. Feed a good-quality forage with long fibers to “increase the bulk of ingesta in the colon.” Avoid concentrates for 10 to 14 days after treatment.
Munsterman recommended eliminating or reducing the amount of concentrates affected horses consume and instead basing the diet on good-quality fiber sources and ensuring adequate water intake.
Large Colon Torsion
Veterinarians always treat this severe and life-threatening form of colic surgically, Munsterman said. Post-surgical feeding depends on the severity of the torsion (twist) and what was done during surgery.
In horses treated early with minimal intestinal resection during surgery, feeding can begin as early as six to 12 hours after treatment, she said. If the torsion is serious in nature and the veterinarian performs extensive surgery and resection, feeding will need to wait at least 12 to 24 hours, she said. If some of the intestine has become ischemic (has a lack of blood flow), horses might not be able to eat for up to 48 hours post-surgery, she added.
When the horse does eat, provide good-quality forage for four to six hours, Munsterman relayed. Feed intake can be increased over the next few days, and the horse should be able to consume his full ration by the third day. Once the horse has been fully reintroduced to feed, he will require a highly digestible diet to maintain body condition, due to the colon resection, she noted. Special considerations for these horses include:
- The horse likely needs to consume good hay with high protein content (alfalfa) at a higher quantity than maintenance horses to prevent weight loss;
- Affected horses need to consume more water than healthy horses (sometimes up to eight liters more) to account for excess water loss in the feces;
- As the digestive tract rebuilds itself, the need for a specialized diet will diminish; and
- If needed, provide oil or soybean meal to encourage weight gain post-surgery.
Munsterman said cecal impactions are the most common cecum disorder resulting in colic, and depending on the case, veterinarians can treat them medically or surgically, she said.
“Feeding after cecal impactions is complicated by a high rate of recurrence,” Munsterman said. Thus, she recommended refeeding slowly and gradually. She suggested only providing water for the first 12 to 24 hours post-resolution, followed by hand-walking and grazing for up to 15 minutes to promote intestinal motility. Next, she suggested providing low residue feeds–such as complete or alfalfa pellets–and reintroducing hay to the diet very gradually. She suggested alfalfa because of its laxative effects.
This type of colic occurs when the cecum telescopes into itself and is always surgical, she said. The severity and procedures performed during surgery dictate how soon post-operatively the horse can begin eating.
Some horses can eat in as little as 12 hours, while others must wait 36 to 48 hours, she relayed. When refeeding begins, offer water before adopting a feeding schedule similar to the one outlined in the “large colon impactions” section. Specifically, grazing promotes cecal motility, so it’s advisable to allow the horse access to grass.
Small Colon Obstructions
Veterinarians select either medical or surgical treatment based on the obstruction’s severity. The two treatment methods have slightly different refeeding procedures, she noted.
Medically managed horses can begin drinking water in the first 12 to 24 hours post-resolution, she noted. After that, she recommended using a similar feeding schedule as one would for a horse with ascending colon impactions. She recommended a forage-only diet for the first few days after impaction resolution.
Horses treated surgically should be held off feed for 36 to 48 hours post-op, Munsterman said, and slowly fed a small quantity of low residue feeds every six hours. These feeds, such as complete feeds or alfalfa pellets, should be fed for the first 10 to 14 days after surgery, she noted. If necessary, owners can continue this diet indefinitely should problems arise when they introduce a normal diet.
No two colic cases will resolve alike, and as such each case requires individual treatment. But understanding refeeding practices before colic strikes can help prepare an owner for whatever might occur in the future.