Dietary Management of Gastrointestinal Disease

Marge Chandler, DVM, MS, MANZCVSc, DACVN, DACVIM, DECVIM-CA, MRCVS The University of Edinburgh

Abstract: Nutrition plays a key role in the management of gastrointestinal disease, and some patients may be managed by dietary therapy alone. Dietary ingredients can have a negative or positive effect on the bowel. Negative factors in a diet may include toxins, allergens, toxic dietary excesses, or nutritional deficiencies. Diet also has a direct effect on intestinal physiology, affecting motility, cell renewal rate, intestinal microbiome, enzyme production, ammonia production, and volatile fatty acid content. This article discusses dietary therapy of acute gastroenteritis, chronic gastroenteropathies, and feline constipation.

utrition plays a key role in the management of gastrointestinal When intractable vomiting is present, oral intake of food (GI) disease, and some patients may be managed by dietary should generally be avoided, but for as short a time as possible. In Ntherapy alone. Dietary ingredients can have a negative or dogs infected with parvovirus, early enteral feeding results in positive effect on the bowel. Negative factors in a diet may include faster resolution of vomiting and diarrhea than does withholding toxins, allergens, toxic dietary excesses, or nutritional deficiencies. food.3 Similar to feeding during diarrhea, feeding small amounts Diet also has a direct effect on intestinal physiology, affecting may improve gastric emptying and a return to normal motility. motility, cell renewal rate, intestinal microbiome, enzyme produc- Highly digestible foods with a low to moderate fat content should tion, ammonia production, and volatile fatty acid content.1 Recent be considered because high-fat diets may slow gastric emptying research in diet and GI disease has resulted in rethinking some and promote vomiting in some patients. Parenteral fluids and elec- traditional approaches to treatment. This article addresses the trolytes should be provided as needed, and antiemetics should be management of several (but far from all) GI diseases and conditions. used if the presence of a GI foreign body has been ruled out.4 Treatment of Acute Vomiting and Diarrhea of Chronic Enteropathies and Inflammatory Bowel Disease Small Intestinal Origin: To Feed or Not To Feed? The terminflammatory bowel disease (IBD) includes a group of Traditionally, dogs and cats with acute vomiting and diarrhea chronic enteropathies characterized by chronic or recurrent due to dietary indiscretion have been managed by withholding vomiting and/or small intestinal diarrhea with histopathologic food for 24 to 48 hours for “bowel rest.” Fasting, even for this evidence of inflammatory cells in the GI tract. The underlying period of time, decreases the length of the intestinal villi, increases cause of IBD is not fully understood; it is likely due to complex the risk of bacterial translocation, and reduces activity of intestinal interactions among genetics, diet, and the intestinal microbiome disaccharide enzymes. In addition, the bowel does not necessarily (microflora). In humans, IBD is thought to be due to dysregulation “rest” when empty: during fasting, dogs experience migrating of the mucosal immune response to the intestinal microbiome or to motility complexes or “housekeeping waves”; cats experience a food antigens. Dysbiosis of the microbiome has also been implicated similar motility pattern. During inflammation, normal motility is as a cause of IBD in dogs,5 and intestinal inflammation is associated likely decreased and ileus and delayed gastric emptying are present.2 with a shift in the microbiome population from members of the “Feeding through diarrhea” (i.e., feeding while a patient still gram-positive Firmicutes (e.g., Clostridiales) to gram-negative shows clinical signs) may help maintain the activity of small intestinal bacteria such as Proteobacteria (e.g., Enterobacteriaceae).6 digestive enzymes and help preserve normal villi morphology. The While the use of immunosuppressive doses of corticosteroids presence of food in the intestine also decreases the risk of bacterial has been a common therapy for IBD, many clinicians are now translocation.3 Further, feeding small amounts may improve intesti- recommending the performance of a diet trial before the use of nal motility and gastric emptying.4 In some cases of osmotic diarrhea, corticosteroids or other immunosuppressive medications. Some feeding worsens clinical signs; therefore, patients should be treated clinicians think that dogs and cats with food-responsive disease are individually and feeding stopped if diarrhea appears to worsen. in a different category than animals with IBD that is not responsive

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to diet change alone; however, dietary antigens are likely to play a diets showed similar initial role in IBD, and many affected animals have intestinal inflammation, response, at a long-term Key Points so the differentiation may not be needed. follow-up (median: about Dietary proteins are the major source of food antigens. The 3.5 years), the dogs on the • As early as possible, consider feeding dogs with acute vomiting inflammation in IBD likely increases intestinal permeability and hydrolyzed diet (13 of 14 and diarrhea a highly digestible, contributes to antigenic exposure. This may result in a pet devel- dogs) were more likely to possibly low-fat food to help oping sensitivity to its diet or treats. To make appropriate dietary still be in remission com- maintain the health and function of recommendations, a full dietary history should be obtained, pared with those on the the gastrointestinal tract. including treats, chews, and foods used for medication. The diet intestinal diet (one of six should be changed (usually over several days) to a highly digestible dogs; three dogs were lost • Chronic small intestinal diarrhea is diet that does not contain a previously fed protein source. All to follow-up). The dogs on often responsive to dietary potential sources of dietary antigens (e.g., treats, some chewable the intestinal diet may have management, and transition to a medications) should be avoided. This can be done by feeding a become sensitized to in- hydrolyzed or novel protein diet novel protein diet or a hydrolyzed protein diet. gredients in the diet, as four should be considered before the use of the dogs improved when of immunosuppressive medications. Novel Protein Diets put on the hydrolyzed diet.11 • In cats with chronic constipation, In a study of cats with chronic idiopathic GI signs, clinical signs In a study of eight cats consider conducting a diet trial improved in 50% of cats, usually within 4 days after a highly di- with IBD, feeding a hydro- using a diet with increased psyllium, gestible novel protein diet was fed. In 20% of these cats, clinical lyzed protein diet resulted a soluble fiber with moderately low signs did not recur after challenge with their previous diet.7 in resolution of clinical signs fermentability. These cats did not have a persistent adverse reaction to food, as within 4 to 8 days in all 8 they did not respond to challenge. It is possible that the novel diet cats, similar to the study allowed repair of the intestines or affected the GI microbiome using a novel protein diet; however, in these cats, a challenge positively. In a study of 65 dogs with chronic GI signs, 39 (60%) with a previous diet resulted in recurrence of the clinical signs.12 responded to a novel protein, salmon, and rice diet fed for 10 days.8 It appears that many dogs and cats with chronic GI signs Which Diet Should Be Fed: Novel Protein or Hydrolyzed Protein? are responsive to dietary therapy with a highly digestible novel The primary role of hydrolyzed protein diets is similar to that of protein diet. Some of these patients may also be able to return to novel protein diets—to diagnose or treat/manage food-sensitive a previous diet, perhaps due to restoration of normal mucosal gastroenteropathies. Many dogs and cats have been exposed to a immunity or other beneficial changes in the intestinal environment.1,4 variety of dietary proteins, but the use of hydrolyzed diets usually It is also possible that factors other than a novel protein source overcomes the challenge of finding a protein source that a pet has may improve clinical signs. not previously eaten. Although uncommon, it is possible for a Some over-the-counter novel protein diets have been contami- patient to react adversely if it is sensitive to the protein source in nated with protein sources not listed in the ingredients, which the hydrolyzed diet. In one study, three of 14 soy-sensitive dogs may result in a lack of resolution of signs.9 fed a hydrolyzed soy diet showed a dermatologic reaction.13 In some cases, using a diet with a very small particle size or avoiding Hydrolyzed Protein Diets the previous dietary protein may be necessary. Some patients The protein in hydrolyzed protein diets has been broken down by have failed an elimination diet trial using a novel intact protein enzymes into small peptides that are less allergenic than entire diet but then responded to a hydrolyzed protein diet.14 proteins. Available diets include hydrolyzed chicken, soy protein, While the needs of each pet and owner should be considered, it or feathers or a combination of these. No studies have compared the may be reasonable to use hydrolyzed diets as a diagnostic tool to effectiveness of these diets for managing diarrhea. Some of these diets determine whether there is a dietary component to GI disease. are made with very small peptides and/or amino acids to minimize As these diets are expensive, an owner may not wish to continue the possibility of an animal developing an antigenic response. feeding them long term. Hydrolyzed diets have very good digestibility. In dogs and While no studies have provided good evidence-based data on cats with severe intestinal disease, the use of hydrolyzed diets may when a diet may be changed, one recommendation is to feed a diet improve nutrient absorption and decrease antigenic exposure.10 that has resulted in clinical improvement for 6 months to 1 year and In a 2010 study,11 26 dogs with chronic GI signs were fed either a then add a single protein source as a trial. If a protein a patient hydrolyzed diet or a highly digestible “intestinal” diet containing tolerates is found, choosing a commercial diet based on this protein proteins from various sources; the latter served as the control. may be beneficial.1 The initial response to both diets was good, with improvement in clinical signs in about 88% of dogs for both diets. Of the dogs Constipated Cats that responded but were later challenged with their original diet, Constipation—infrequent or absent defecation associated with about two-thirds of the dogs on either diet relapsed. While the fecal retention in the colon and rectum—is a relatively common

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clinical problem in cats. It may lead to obstipation, which is in- Conclusion tractable constipation in which defecation becomes impossible The GI tract is the organ most directly affected by nutrition, and without medical intervention. The potential etiologies of consti- new studies are continually improving the diagnosis and dietary pation include diet, lack of exercise, mechanical obstruction, therapy of GI disease. neurologic disease, dehydration, administration of drugs, and some endocrinopathies. Medical treatment includes addressing References the underlying cause, if possible; correcting fluid and electrolyte 1. Guilford WG. Nutritional management of gastrointestinal disease. In: Guilford WG, disorders; and removing feces by using laxatives, enemas, proki- Meyer DJ, Strombeck DR, eds. Strombeck’s Small Animal Gastroenterology. 3rd ed. Philadelphia, PA: WB Saunders; 1996:889-910. 15 netics, and surgery, if necessary. 2. Marks SL. Enteral and parenteral nutrition. In: Washabau RJ, Day MJ. Canine and Dietary recommendations have included feeding highly digest- Feline Gastroenterology. St Louis, MO: Elsevier Saunders; 2013:429-444. ible diets to decrease the amount of feces and increasing dietary 3. Mohr AJ, Leisewitz AL, Jacobson LS, et al. Effect of early enteral nutrition on intestinal fiber to improve colonic motility. If a cat develops megacolon permeability, intestinal protein loss, and outcome in dogs with severe parvoviral enteritis. with little to no motility, surgical subcolectomy and provision of J Vet Intern Med 2003;17(6):791-798. 4. Cave N. Nutritional management of gastrointestinal disease. In: Fascetti AJ, Delaney a highly digestible, low-residue diet may be indicated. SJ. Applied Veterinary Clinical Nutrition. Chichester, UK: Wiley-Blackwell; 2012:175-220. For cats with constipation but not megacolon, the use of added 5. Simpson KW, Jergens AE. Pitfalls and progress in the diagnosis and management of dietary fiber may be indicated. Fiber is plant material resistant to canine inflammatory bowel disease. Vet Clin North Am Small Anim Pract 2011;41:381-398. digestion by the small intestine. A wide variety of dietary fibers 6. Suchodolski JS, Xenoulis PG, Paddock CG, et al. Molecular analysis of the bacterial exist, including cellulose, hemicellulose, pectins, gums, and lignins. microbiota in duodenal biopsies from dogs with idiopathic inflammatory bowel disease. Vet Microbiol 2010;142:394-400. Fibers are divided into soluble and nonsoluble types. Generally, 7. Guilford WG, Jones BR, Markwell PJ, et al. Food sensitivity in cats with chronic idio- soluble fibers attract water, form gels, delay gastric emptying, and pathic gastrointestinal problems. J Vet Intern Med 2001;15:7-13. are highly fermentable in the colon. Insoluble fibers may hasten 8. Luckschander N, Allenspach K, Hall J, et al. Perinuclear antineutrophilic cytoplasmic gastric emptying, are not gel forming, are less fermentable in the antibody and response to treatment in diarrheic dogs with food responsive disease or colon, and provide bulk within the colon. Many fiber sources inflammatory bowel disease. J Vet Intern Med 2006;20:221-227. 9. Raditic DM, Remillard RL, Tater KC. ELISA testing for common food antigens in four have properties of both classifications. The “crude fiber” reported dry dog foods used in dietary elimination trials. J Anim Physiol Anim Nutr (Berl) on pet food labels is mostly insoluble and does not include the 2011;95(1):90-97. amount of soluble, more fermentable fiber sources. 10. Cave NJ. Hydrolyzed protein diets for dogs and cats. Vet Clin North Am Small Anim Recommendations for diets for cats with constipation have Pract 2006;36:1251-1268. included the use of fibers with low solubility to provide fecal bulk 11. Mandigers PJ, Biourge V, van den Ingh TS, et al. A randomized, open-label, positively controlled field trial of a hydrolysed protein diet in dogs with chronic small bowel enter- and improve colonic motility by distending the colon. Insoluble opathy. J Vet Intern Med 2010;24:1350-1357. fibers can decrease moisture in stool, and many cats with consti- 12. Mandigers PJ, Biourge V, German A. Efficacy of a commercial hydrolysate diet in pation already have a distended colon with dry feces, which would eight cats suffering from inflammatory bowel disease or adverse reaction to food. Tijdsche make the use of insoluble fiber less appropriate in theses cats. Diergeneesk 2010;135:668-672. Fermentable fiber increases the amount of short-chain fatty acids 13. Jackson HA, Jackson MW, Coblentz L, Hammerberg B. Evaluation of the clinical and allergen specific serum immunoglobulin E response to oral challenge with cornstarch, corn, in the stool; this is thought to positively affect colon motility. soy and a soy hydrolysate diet in dogs with spontaneous food allergy. Vet Dermatology However, too much fiber fermentation can lead to diarrhea. 2003;14:181-187. Psyllium—a soluble fiber with low fermentability—produces 14. Marks SL, Laflamme DP, McAloose D. Dietary trial using a commercial hypoallergenic a mucilaginous gel when combined with water. It also provides diet containing hydrolysed protein for dogs with inflammatory bowel disease. Vet Ther stool bulking. In people with constipation, the addition of psyllium 2002;3:109-119. 15. Guildford WG, Strombeck DR. Miscellaneous disorders of the bowel, abdomen, and increases stool frequency and improves stool consistency. A anorectum. In: Guilford WG, Meyer DJ, Strombeck DR, eds. Strombeck’s Small Animal commercial psyllium-enriched dry diet has been studied in an Gastroenterology. 3rd ed. Philadelphia, PA: WB Saunders; 1996:503-531. uncontrolled trial in cats with constipation.16 Clinical improvement 16. Freiche V, Houston D, Weese H, et al. Uncontrolled study assessing the impact of a and improved stool quality were seen in more than 80% of the psyllium-enriched extruded dry diet on faecal consistency in cats with constipation. J cats within a week of starting the diet. In many of the cats, doses Feline Med Surg 2011;13:903-911. of lactulose and cisapride could be decreased.16 The long-term use of this diet and its potential for decreasing the risk of megacolon have not yet been studied.

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