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Equine November/December 2007 (Vol 2, No 6)

Therapeutics in Practice: Feeding Management of Horses Recovering from Colic

by Raymond J. Geor, BVSc, MVSc, PhD, DACVIM

    Knowledge of the benefits and complications associated with different modes of nutritional support in horses recovering from colic is limited, and recommendations on the feeding management of these patients vary widely. In general, however, the mode of nutritional support depends on the horse's appetite and the underlying cause of colic, regardless of whether complications arise during convalescence. Horses with simple colic (i.e., no specific diagnosis) can quickly return to normal feeding with no special dietary treatment required during recovery. Water can be offered soon after resolution of large colon obstruction, and if gastrointestinal function is adequate, small and frequent feedings of high-quality forage or a low-bulk complete feed can be offered as soon as 3 to 6 hours after surgery (or resolution of an impaction), with a return to free-choice hay feeding after 24 to 48 hours.

    A more conservative approach is indicated after small intestinal obstruction because of the increased risk for ileus and complications associated with sites of enterotomy or anastomosis. In these patients, water should be offered after gastric reflux ceases, followed by small, frequent feedings of a soft diet, then a gradual (2- to 4-day period) reintroduction to normal diet if clinical evidence of intestinal motility and transit of ingesta exists. Providing only intravenous fluids and electrolytes and delaying postcolic feeding could slow recovery and may, in fact, contribute to development of some postoperative complications, including ileus.1 In horses treated for surgical colic, there was a significant correlation between several serum biochemical indicators of negative energy balance and incisional complications.2 These findings are consistent with data demonstrating that nutrient deprivation delays wound healing, impairs immune function, and increases morbidity and mortality in critically ill human patients.3-5 Conversely, nutritional therapy in human patients decreases the risk for complications, mitigates loss of muscle mass, improves wound healing, and shortens duration of hospitalization.3-5 Partial parenteral nutrition (PN) can be administered to horses with ongoing intestinal dysfunction (i.e., ileus or gastric reflux) and should be considered when the period of postcolic starvation exceeds 24 to 48 hours.

    Nutrient Requirements

    The nutritional requirements of horses following colic surgery or other gastrointestinal illness have not been determined. Primary considerations include requirements for energy (calories) and protein. In healthy adult horses, daily digestible energy (DE) needs are approximately 32 to 33 kcal/kg of body weight (BW)/day, as calculated by the following formula6:

    DE (Mcal/day) = 1.4 + [0.03 x kg BW]

    However, the energy needs of hospitalized horses are probably much lower because of reduced energy expenditure. The DE requirement of healthy horses kept in stalls is approximately 70% of the DE required by horses kept at pasture. The resting (or stall maintenance) energy requirement (RER) of a healthy horse can be estimated by the following equation7:

    RER (kcal/day) = [21 kcal x kg BW] + 975 kcal

    The energy needs of horses in the early phase of recovery from colic also may be lower because of feed withdrawal, wherein energy losses associated with digestion may be decreased by as much as 15% to 20%.8 Conversely, energy demands in these patients may be increased by an underlying disease process (e.g., systemic inflammatory response syndrome) or by surgery. Some human studies have demonstrated that abdominal surgery increases energy needs by about 30%,3 while others have reported minimal change in energy requirements after gastrointestinal surgery.9 On the other hand, septic complications can increase energy requirements by 50% to 100%.10 In the absence of data on the effects of illness on the energy needs of horses, I recommend that the caloric requirements of horses recovering from colic be based on the RER equation (i.e., 21 kcal DE/kg of BW/day). After 2 to 4 days of feeding at this level, the ration can be gradually increased until true maintenance DE intake is achieved.

    Protein requirements must be considered in light of caloric intake. When the energy supply from carbohydrates and fat is limited, endogenous protein is used for energy, contributing to a loss of lean body mass. Therefore, in developing a nutritional plan, clinicians should first ensure that minimal energy needs are met, then calculate protein requirements. For human patients, a protein:energy ratio of 0.8 to 1 g/40 kcal is suggested, equivalent to 0.8 to 1 g protein/kg BW/day.11,12 For a 1,100-lb (500-kg) horse with a maintenance requirement of approximately 16 Mcal DE per day, this equates to 1.25 g of crude protein/kg of BW. Because the efficiency of digestion for most dietary proteins in horse feeds is about 70%,6 this level of crude protein will provide approximately 0.9 g of available protein/kg of BW/day. In the absence of data concerning protein metabolism in sick horses, the maintenance protein requirement is reasonable for nutritional management of colic patients. For parenteral feeding, an appropriate target is 0.6 to 0.8 g of protein/kg of BW/day (1 g/40 to 50 kcal) because of the higher metabolic availability of amino acids administered via the intravenous route.12-14

    Modes of Nutritional Support

    The three primary modes of nutritional therapy are (1) voluntary enteral feeding, (2) assisted enteral feeding, and (3) parenteral nutrition.8,15 In general, the mode of nutritional support used in an individual patient is highly dependent on the underlying cause of the colic, any complications that arise during convalescence, and the horse's appetite. The preferred option is a controlled return to normal voluntary intake. Prerequisites are absence of gastric reflux, good intestinal motility, and a willingness to eat. Horses with simple colic rarely need special dietary management. Feed and water should be withheld during the colic episode, with resumption of normal feeding after abatement of colic signs. An evaluation of diet may be indicated when there is suspicion that diet or feeding practice contributed to the episode of colic. Some clinicians recommend withholding grain feedings for a few days to limit gas production in the hindgut.

    Horses recovering from intestinal surgery can resume feeding when there is clinical evidence of intestinal motility. Initially, the horse should be fed small amounts (e.g., 1.1 lb [0.5 kg]) of good-quality forage (e.g., grass hay, alfalfa) four to six times daily, with a gradual increase in the volume of feedings over the following days, provided the horse tolerates the increase in feeding. Alternatively, the horse may be allowed to graze pasture for 20 to 30 minutes several times throughout the day or be provided a highly digestible, low-bulk pelleted feed such as those marketed for use in older horses ("senior feeds"). Grains should be avoided for at least 10 to 14 days after surgery because of concern that excess starch may further disturb an already disrupted hindgut microbial community. Thereafter, grain or concentrate feeding can be resumed, starting at a rate of about 2.2 lb (1 kg)/day (for a 1,100-lb horse) and increasing by no more than 1.1 to 1.65 lb (0.5 to 0.75 kg)/day. Voluntary intake should account for at least 75% to 80% of the horse's RER DE requirements by the second or third day of feeding. For example, 75% of the RER of a 1,100-lb horse (approximately 9 Mcal DE) would be met by the consumption of about 8.8 lb (4 kg) of first-cut timothy hay that contains approximately 2.3 Mcal DE/kg (as fed). Although labor intensive, weighing the offered hay and the feed remaining in the stall is the only means to determine the adequacy of caloric intake.

    More challenging is the nutritional management of anorectic or inappetent horses or horses with severe intestinal compromise that results in ileus and precludes enteral nutrition. Inappetent horses should be offered a variety of palatable feedstuff, including fresh grass, in an attempt to stimulate intake. However, failure to consume at least 75% of stall maintenance DE requirements for more than 48 hours is an indication for initiation of nutritional support. Earlier intervention may be indicated for horses in poor body condition (body condition score <3 on a scale of 1 to 9 in which 1 indicates emaciation and 9 indicates obesity) or with a recent history of weight loss, old horses (age >20 years), horses with suspected or confirmed sepsis or endotoxemia, lactating mares or mares in the last trimester, and ponies, donkeys, or miniature horses with documented hypertriglyceridemia (>500 mg/dl).7,15"17 PN should be considered for horses with ileus and other intestinal conditions that prevent voluntary or assisted enteral feeding, particularly when the withholding of oral feeding is expected to exceed 48 to 72 hours.

    Assisted Enteral Feeding

    Dietary options for assisted enteral feeding include human enteral products, commercial pelleted horse feeds, and homemade recipes.8,15,17,18 Human formulations19-21 (Vital HN and Osmolyte HN; Ross Laboratories, Columbus, OH) are devoid of fiber, making them easier to administer (11 to 12 L/day). Another option is to use a pelleted feed that contains fiber,19 such as Equine Senior (Land O'Lakes-Purina Feed, St. Louis, MO). This and similar feeds contain about 2.6 Mcal DE/kg (as fed). Vegetable oils (75 to 375 ml/day) can be added to increase the caloric density of the ration. Alternatively, the alfalfa-dextrose-casein mixture first described by Naylor et al22 can be used for enteral feeding. In healthy horses, the administration of this diet was reported to maintain body weight and serum biochemical parameters within reference limits. However, occasional diarrhea and laminitis were reported complications.

    Pelleted feeds can be made into a slurry by soaking them in water and mixing them in a blender to reduce the size of feed particles. Intermittent nasogastric intubation or placement of an indwelling nasogastric tube can be used to facilitate feeding. An internal tube diameter of at least 12.5 mm (14 French) is recommended. The tube should be open ended, rather than fenestrated, to prevent clogging. The tube should be positioned in the stomach rather than the distal esophagus to minimize the risk of reflux of feed around the tube. The rate of diet administration should be gradually increased over a 3- to 7-day period. A suggested rate of introduction is to administer one-quarter of the total target volume of feed on day 1, one-half of the total volume on day 2, three-quarters of the total volume on day 3, and the total volume on day 4 or 5. Ideally, the enteral diet will be administered in 4 to 6 feedings/day with no more than 6 L/feeding for a 1,100-lb horse. The horse must be monitored for signs of colic, gastrointestinal ileus, abdominal and gastric distention, and increased digital pulses. Ultrasonographic examinations may be useful for evaluation of gastric distention and intestinal motility. Development of gastric reflux, ileus, diarrhea, or laminitis suggests intolerance of enteral feeding and is an indication to discontinue or decrease the volume and frequency of feedings. In these horses, partial or total PN may be required. Horses should also be monitored for development of complications associated with repeated or indwelling nasogastric intubation, including rhinitis, pharyngitis, and esophageal ulceration.22,23 Horses receiving enteral diets should produce feces, although the volume may be diminished.

    Parenteral Nutritional Support

    A detailed description of methods of PN support is beyond the scope of this column, and readers are referred elsewhere13,14,16,24 for comprehensive discussion of this subject. As with enteral nutritional support, the goal of PN is to provide calories and amino acids to limit loss of condition. Although there are several reports of the use of PN in colic patients, few studies have evaluated the clinical benefits of this mode of nutritional support.13,14,16 A study by Durham and colleagues13,14 examined the effects of PN in 15 horses recovering from resection and anastomosis of strangulated small intestine (see Small Intestinal Disorders, p. 350).

    Carbohydrates and lipids are the primary sources of energy in PN solutions. Amino acids are added to meet protein (amino acid) requirements. It is important to provide at least 100 to 150 nonprotein calories per gram of nitrogen in the PN formula to avoid the use of amino acids for energy. Because protein is approximately 16% nitrogen, the grams of nitrogen can be estimated by multiplying the grams of protein in the mixture by 0.16. PN solutions with and without lipids can be used (i.e., dextrose-amino acid or dextrose-lipid-amino acid mixtures). A dextrose-amino acid mixture that has been successfully applied for PN support of postoperative colic patients provided daily gross energy of 20 to 22 kcal/kg/day.14,16

    PN solutions should be administered through a dedicated intravenous catheter inserted into a large vein (e.g., jugular) to minimize the risk for complications associated with the infusion of hyperosmotic solutions. Alternatively, a double-lumen catheter can be used, allowing the PN solution to be given through one port and medications and other fluids through the other port. The initial rate of PN solution administration should be only 30% to 35% of target calorie provision; the rate can be increased by 25% every 6 to 8 hours if there are no complications, such as marked hyperglycemia and glucosuria.

    As with assisted enteral feeding, close clinical monitoring is imperative. Urine and blood glucose concentrations should be measured every 4 to 8 hours because some horses develop glucose intolerance, hyperglycemia, and osmotic diuresis. Serum blood urea nitrogen, triglycerides, and electrolytes should be monitored daily and body weight measured. Maintenance of body weight provides the best guide to the effectiveness of nutritional support. Glucose intolerance (persistent hyperglycemia) requires a reduction in the rate of glucose administration and/or the administration of insulin.

    Transition to Voluntary Feeding

    As appetite returns and oral feeding is no longer contraindicated, small amounts of palatable feed (e.g., fresh grass) should be offered. If these meals are tolerated, the level of assisted feeding can be gradually reduced as the provision of feed for voluntary consumption is increased. Nutritional support can be withdrawn when voluntary feed intake provides at least 75% of stall maintenance calorie and protein requirements.

    Feeding Management of Specific Gastrointestinal Conditions

    Small Intestinal Disorders

    Abnormal intestinal motility is of primary concern following small intestinal surgery, particularly in horses requiring resection and anastomosis of the small intestine. Long-term complications include peritonitis, impaction or leakage at the site of enterotomy or anastomosis, and adhesion formation.25 There are anecdotal reports that early provision of enteral nutritional support or PN is associated with decreased incidence or severity of postoperative ileus, but few data are available from controlled studies on this or other complications. Durham and colleagues13,14 examined the effects of postoperative PN in 15 horses (versus 15 control horses) recovering from resection and anastomosis of strangulated small intestine. These authors reported no beneficial effect of PN on time to first oral feeding, duration of hospitalization, costs of treatment, or short-term survival (up until 5 months after discharge), although the PN protocol did confer improved nutritional status as reflected by lower serum concentrations of triglycerides and total bilirubin and higher concentrations of glucose. However, the duration and volume of postoperative gastric reflux were greater in the PN group than in the control horses. The authors concluded that further study of a larger number of horses is required to determine the clinical benefits and possible harmful effects of PN in horses recovering from small intestinal surgery. PN support is also advocated for horses with duodenitis-proximal jejunitis because of the protracted nature of the ileus and gastric reflux in these cases.

    Consumption of high-bulk feeds, such as long-stem hay, in the early postoperative period may cause distention at sites of enterotomy, anastomosis, or sutured esophageal wounds, increasing the probability for wound dehiscence and fatal complications.26 Horses with esophageal injuries that are sutured closed can make a full recovery if fed a soft diet (e.g., slurry made from pelleted feeds) for 8 to 10 weeks following the injury,26 a finding that is possibly applicable to the nutritional management of horses following small intestinal surgery. Enteral feeding should not be started until gastrointestinal function is adequate, as indicated by the presence of borborygmi and the absence of gastric reflux. A soft, low-bulk ration such as fresh grass (hand grazing) and mashes or slurries made from alfalfa pellets or pelleted complete feeds is recommended. Molasses may be added to the mash or slurry to enhance palatability. Small meals (1.1 to 1.65 lb) should be fed every 3 to 4 hours to minimize physical stress at the anastomosis site. In uncomplicated cases of resection and anastomosis, long-stem hay should be gradually introduced after 3 to 4 days of soft diet feeding. Bran mashes are not recommended for horses recovering from small intestinal surgery.

    Large Intestinal Disorders

    Horses with impaction of the large intestine (cecum or colon) should not be fed until after resolution of the impaction. Fresh grass, alfalfa pellets, chopped alfalfa hay, and other sources of highly digestible fiber are preferred. Pelleted feeds may allow an increased rate of passage due to smaller particle size compared with long-stem roughage. Grain should be withheld until normal transit of ingesta is confirmed. A thorough oral examination should be performed to establish whether inadequate mastication of feed is an underlying cause of the impaction.

    Diarrhea is a complication of all types of colic surgery, but one study suggests that the risk is highest in horses undergoing enterotomy for large intestinal disorders.27 However, horses fed grass hay were half as likely to develop severe diarrhea as horses not fed grass hay. Horses should be fed small amounts of grass or soft grass hay at frequent intervals (every 2 to 3 hours) as early as 12 hours after surgery, providing there is no evidence of gastric reflux or poor intestinal motility. First-cut hay is preferred because of its higher dry-matter digestibility compared with more mature forages. No grain or concentrate should be introduced until 10 to 14 days after surgery, but low-bulk pelleted feed may be beneficial during this period.

    Long-term dietary modification is required for horses with extensive resection of the large colon but not when the cecum alone is removed. Gastrointestinal passage time and fiber, protein, and phosphorus digestion are decreased after resection of more than 90% of the large colon,28-30 and chronic diarrhea, weight loss, and hypophosphatemia may be complications.31 With appropriate dietary management, however, these horses can maintain adequate body condition. In the early postoperative period, horses that have undergone extensive resection should be fed small amounts of a low-bulk feed (e.g., alfalfa pellets, pelleted commercial feed). Subsequently, legume forage should be the predominant component of the ration. Following experimental colon resection, a ration of alfalfa hay or an alfalfa-timothy hay mix provided better results compared with straight grass hay, perhaps due to higher digestibility and protein content of the alfalfa-based rations.30 Supplemental phosphorus can be provided as a feed additive or by feeding 1.1 lb of wheat or stabilized rice bran daily. If additional calories are required for weight maintenance, a "fat and fiber" concentrate rather than grain or sweet feed is recommended.

    Downloadable PDF

    *Dr. Geor discloses that he has received financial support from Waltham Centre for Pet Nutrition.

    1. Freeman DE, Hammock P, Baker GJ, et al: Short- and long-term survival and prevalence of postoperative ileus after small intestinal surgery in the horse. Equine Vet J Suppl (32):42-51, 2000.

    2. Protopapas K: Studies on Metabolic Disturbances and Other Postoperative Complications Following Equine Colic Surgery. DVetMed Thesis, University of London.

    3. Heyland DK: Nutritional support in the critically ill patient: A critical review of the evidence. Crit Care Clin 14:423-440, 1998.

    4. Roberts PR, Zaloga GP: Enteral nutrition, in Shoemaker WC, Ayres SM, Grenvik A, Holbrook PR (eds): Textbook of Critical Care, ed 4. Philadelphia, WB Saunders, 2000, pp 875-898.

    5. Jeejeebhoy KN: Enteral and parenteral nutrition: Evidence-based approach. Proc Nutr Soc 60:399-402, 2001.

    6. National Research Council: Nutrient Requirements of Horses, ed 5. Washington, DC, National Academy Press, 1989.

    7. Pagan JD, Hintz HF: Equine energetics. I. Relationship between body weight and energy requirements in horses. J Anim Sci 63:815-821, 1986.

    8. Rooney DK: Clinical nutrition, in Reed S, Bayly WM (eds): Equine Internal Medicine. Philadelphia, WB Saunders, 1998, pp 216-250.

    9. Sternberg JA, Rohovsky SA, Blackburn GL, et al: Total parenteral nutrition for the critically ill patient, in Shoemaker WC, Ayres SM, Grenvik A, Holbrook PR (eds): Textbook of Critical Care, ed 4. Philadelphia, WB Saunders, 2000, pp 889-908.

    10. Mechanik JI, Brett EM: Nutrition support of the chronically critically ill patient. Crit Care Med 18:597-618, 2002.

    11. Adam S, Forrest S: ABC of intensive care. Br Med J 319:175-178, 1999.

    12. Waitzberg DL, Plopper C, Terra RM, et al: Postoperative total parenteral nutrition. World J Surg 23:560-564, 1999.

    13. Durham AE, Phillips TJ, Walmsley JP, et al: Nutritional and clinicopathological effects of post operative parenteral nutrition following small intestinal resection and anastomosis in the mature horse. Equine Vet J 36:390-396, 2004.

    14. Durham AE, Phillips TJ, Walmsley JP, et al: Study of the clinical effects of postoperative parenteral nutrition in 15 horses. Vet Rec 153:493-498, 2003.

    15. Magdesian KG: Nutrition for critical gastrointestinal illness: Feeding horses with diarrhea or colic. Vet Clin Equine 19:617-644, 2003.

    16. Lopes MA, White NA: Parenteral nutrition for horses with gastrointestinal disease: A retrospective study of 79 cases. Equine Vet J 34:250-257, 2002.

    17. Naylor JM, Kronfeld DS, Acland H: Hyperlipemia in horses: Effects of undernutrition and disease. Am J Vet Res 41:899-905, 1980.

    18. Dunkel B, McKenzie HC: Severe hypertriglyceridemia in clinically ill horses: Diagnosis, treatment and outcome. Equine Vet J 35:590-595, 2003.

    19. Fascetti AJ, Stratton-Phelps M: Clinical assessment of nutritional status and enteral feeding in the acutely ill horse, in Robinson NE (ed): Current Therapy in Equine Medicine, ed 5. Philadelphia, WB Saunders, 2003, pp 705-710.

    20. Sweeney RW, Hansen TO: Use of a liquid diet as the sole source of nutrition in six dysphagic horses and as a dietary supplement in seven hypophagic horses. JAVMA 197:1030-1032, 1990.

    21. Buechner-Maxwell VA, Elvinger F, Thatcher CD, et al: Physiologic response of normal adult horses to a low residue liquid diet. J Equine Vet Sci 23:310-317, 2003.

    22. Naylor JM, Freeman DE, Kronfeld DS: Alimentation of hypophagic horses. Compend Contin Educ Pract Vet 6:S93-S99, 1984.

    23. Stick JA, Derksen FJ, Scott EA: Equine cervical esophagostomy: Complications associated with duration and location of feeding tubes. Am J Vet Res 42:727-732, 1981.

    24. Holcombe SJ: Parenteral nutrition for colic patients, in Robinson NE (ed): Current Therapy in Equine Medicine, ed 5. Philadelphia, WB Saunders, 2003, pp 111-115.

    25. MacDonald MH, Pascoe JR, Stover SM, et al: Factors influencing survival after small intestinal resection and anastomosis in 140 horses. Vet Surg 18:66- 72, 1989.

    26. Stick JA, Slocombe RF, Derksen FJ, et al: Esophagostomy in the pony: Comparison of surgical techniques and forms of feed. Am J Vet Res 44:2123-2132, 1983.

    27. Cohen ND, Honnas CM: Risk factors associated with development of diarrhea in horses after celiotomy for colic (1990-1994). JAVMA 209:667-673, 1996.

    28. Bertone AL, Van Soest PJ, Stashak TS: Digestion, fecal and blood variables associated with extensive large colon resection in the horse. Am J Vet Res 50:253-258, 1989.

    29. Bertone AL, Van Soest PJ, Johnson D, et al: Large intestinal capacity, retention times, and turnover rates of particulate ingesta associated with extensive large colon resection in horses. Am J Vet Res 50:1621-1627, 1989.

    30. Bertone AL, Ralston SL, Stashak TS: Fiber digestion and voluntary intake in horses after adaptation to extensive large colon resection. Am J Vet Res 50:1628-1632, 1989.

    31. Arighi M, Ducharme NG, Horney FD, et al: Extensive large colon resection in 12 horses. Can Vet J 28:245-248, 1987.

    References »

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