Diet and Chronic Enteropathy

The gastrointestinal tract (GIT) is impacted directly by the diet more than any other part of the body. It is affected by the nutrients, the frequency and timing of meals, and the effect on the microbiome. The diet may contain toxins, allergens, nutritional excesses or deficiencies. The diet also has a direct effect on GI physiology, affecting motility, cell renewal rate, enzyme production, immune functions, ammonia production, and volatile fatty acid content. Nutrition plays a key role in the management of many GI diseases, and many cases may be managed by dietary therapy alone.

Nutritional Assessment

Nutritional assessment is part of the routine history taking and physical examination. Nutritional assessment has two parts: a screening evaluation and an extended evaluation if areas of concern are found. The screening evaluation should be performed at every veterinary visit and includes a diet history, body weight, body condition score (BCS), muscle condition, and evaluation of the coat and teeth.

A complete dietary history is especially crucial for patients with GI disease. Often the pet has access to treats, foods provided to give medications, or outside food sources (e.g., scavenging or hunting) which the owner may not consider part of the “diet”, so the questioning must be done carefully.

Chronic Diarrhoea

Chronic diarrhoea is diarrhoea which has lasted longer than 2 weeks. It has many potential aetiologies, including adverse reactions to food, inflammatory bowel disease/ chronic enteropathy, parasites, infectious agents, neoplasia, and systemic disorders such as pancreatitis, pancreatic insufficiency, kidney or liver disease, and hypoadrenocorticism.

Large vs Small Intestinal Diarrhoea

One of the first diagnostic steps is to determine if the diarrhoea is large or small intestinal in origin or both. Many patients exhibit signs which fall into “both” categories, which may be due to small bowel disorders affecting the large bowel function or disease which involves both the small and large bowel. Up to 30% of dogs with chronic diarrhoea have diffuse disease of the gastrointestinal tract. The classic signs of large vs small intestinal diarrhoea are presented here.

Inflammatory Bowel Disease (IBD) or Chronic Enteropathy (CE)

Canine and feline IBD or CE is a heterogeneous group of disorders characterized by persistent or recurrent gastrointestinal signs and in the case of IBD also an inflammatory infiltrate within the GIT. It may affect the stomach, small intestine, colon or any combination of these organs. The infiltration is most often lymphoplasmacytic but may include eosinophilic and neutrophilic infiltrates and may be associated with crypt abscessation and/or lacteal dilation with protein-losing enteropathy (PLE). The underlying cause is not fully understood and is likely to be multifactorial. “ When the disorder affects the small intestine “chronic enteropathy” is probably a better term than “inflammatory bowel disease” in dogs and cats, because the treatment and outcome of the disease is very different from that of inflammatory bowel disease in humans¹.

About two-thirds of canine CE cases respond to an elimination diet trial with a hydrolysed protein diet or novel ingredient diet^2,3 (see below). Hydrolysed diets may improve nutrient absorption and decrease antigenic exposure. In dogs which don’t respond to dietary therapy, about 16% will respond to antibiotics (e.g., metronidazole or tylosin) and about another fifth may require immunosuppressive medications (prednisolone, cyclosporine). Food responsive dogs have a better outcome than the other groups². In a study comparing a highly digestible “intestinal” diet and a hydrolysed diet in dogs with chronic small intestinal disease, both diets improved clinical signs initially; however, long-term remission at one year was better using the hydrolysed diet⁴. Thirty-one of 39 dogs with food responsive chronic diarrhoea did not have a recurrence of clinical signs when switched back to their original diet after 14 weeks of elimination diet trial⁵. A diet with high protein, low carbohydrate, and moderate fat was effective in resolving diarrhoea in 7/15 cats⁶. A highly digestible diet appears to be effective regardless of the fat content⁷.

Anorexia and Poor Appetite as a GI Sign

There are many reasons for decreased appetite or anorexia. Food responsive enteropathy can cause nausea and vomiting and, subsequently, lead to learned food aversion (LFA). Especially in young dogs that show intermittent GI signs and reduced appetite, or are “finicky eaters”, LFA secondary to CE should be suspected. An important differential diagnosis for poor appetite is hypoadrenocorticism, which should be ruled out either by basal cortisol measurement or ACTH stimulation test⁸ (Bovens et al. 2014).

Diet Trial

Adverse reactions to food are diagnosed using elimination-challenge trials. Dietary trials confirm or rule out adverse reactions to food but do not establish an immune mediated basis for the reaction, although that does not affect the case management. Ingredients previously fed should be avoided or a hydrolyzed protein diet can be fed. Hydrolysed proteins are generally less antigenic than whole proteins. Absolutely no other foods or ingredients should be fed during the diet trial as this makes it impossible to confirm that diet is part of the problem. Counselling the owner on feeding management, including the feeding of treats or snacks, is key to the success. Dogs with antibiotic responsive enteropathy often respond better if the antimicrobial therapy is combined with an elimination diet. Animals that respond to elimination diets usually do so within 2 weeks, although rare patients may require 4–6 weeks.

To confirm an adverse reaction to food, a rechallenge or provocation is necessary. The initial food in reintroduced or individual ingredients from the initial diet are added to the elimination diet one by one. Cases with gastrointestinal disease usually react within several days. Many clients do not want to rechallenge and the pet can be kept on the test diet if it is complete and balanced or another novel protein complete diet can be tried¹⁰.

If an elimination diet trial does not resolve the CE signs, additional diagnostics and therapies are warranted. Dogs with idiopathic antibiotic-responsive diarrhoea respond well to antibacterials (e.g. metronidazole or tylosin).

Some chronic inflammatory enteropathy (CIE) patients fail to respond to diet or antibiotics. Definitive diagnosis of CIE is based on histology; therefore, endoscopy and histopathological evaluation of mucosal biopsies are needed before initiating the immunosuppressive medication (e.g., corticosteroids, cyclosporine or chlorambucil).

Prebiotics and Probiotics

Prebiotics are complex carbohydrates which are fermentable, promote the growth of beneficial intestinal bacterial and decrease the growth of pathogenic bacteria, e.g., fructooligosaccharide and mannonoligosaccharides. Probiotics containing non-pathogenic bacteria, such as Bifidobacterum or Enterococcus faecium, are used to increase the ratio of normal to pathogenic GI microbes, which have a variety of effects on the intestine.

Cobalamin (Vitamin B₁₂) and Folate

Many animals with CE are cobalamin deficient^11,12. Cobalamin is needed for GI epithelial cell turnover and repair, and in many feline GI cases signs won’t resolve until cobalamin has been repleted. Serum cobalamin concentrations are usually measured simultaneously with serum folate concentrations. Folate can become deficient when cobalamin is replaced and may also need to be supplemented. Cobalamin has previously been administered parenterally, although a recent study showed that oral cobalamin supplementation was effective in normalizing serum cobalamin concentrations^12,13.

References

References are available upon request.