Managing chronic enteropathies in pets: diet, fiber and the microbiome

Vomiting, diarrhea and weight loss are all common reasons for pets to visit a veterinarian. They may indicate a chronic enteropathy. As approximately 60% of dogs with chronic enteropathy are thought to respond to dietary treatment, this is considered the gold standard for symptom control, and should be used as the first line of therapy. Dietary management for these cases may include foods containing novel or hydrolyzed protein, changes to fiber content or practices that alter the pet’s microbiome.

Chronic enteropathies: what are they?

These gastrointestinal conditions represent a group of symptoms in cats and dogs that manifest as diarrhea, vomiting, anorexia and/or weight loss over a period of more than 3 weeks, when all other diseases with similar symptoms have been excluded. The prevalence of this condition is estimated to be 2.1% to 2.9%. Chronic enteropathy syndrome can be divided into diet-responsive, antibiotic-responsive and immunosuppressive-responsive according to the response to treatment.

Chronic intestinal disease in pets could be compared to irritable bowel disease (IBD) in humans, where there are many theories about the disease, but still many unknowns. A complex interplay between the immune system, the gut microbiome and dietary components is thought to lead to this chronic disease with such severe manifestations. However, it is fairly clear that food intolerances and allergies, combined with an imbalanced microbiome, are at the heart of the cause.

In human IBD, gluten is defined as the main allergen that triggers the first gastrointestinal symptoms. Allergy to gluten has also been noted in pets, with a breed-specific predisposition in Irish setters and border terriers, but the prevalence in the general pet population is low. Instead, animal proteins – especially poultry and beef – are considered the most common allergens for pets, but nowadays other common proteins such as fish, lamb or turkey should be avoided.

The importance of a dietary trial

As this is a chronic disease requiring frequent visits to the veterinarian, owners are usually highly motivated to obtain treatment that will keep clinical signs in remission for as long as possible. In most cases, the first diagnostic and therapeutic step is a diet trial, as studies have shown that most dogs respond favorably over a long period of time to appropriate dietary intervention. Pets whose gastrointestinal symptoms stabilize within a few weeks can be considered to have a diet-responsive chronic enteropathy. If stabilization does not occur, treatment with immunosuppressants should be considered.

There are 2 dietary approaches that can be followed: a novel protein diet or a hydrolyzed protein diet.

A novel protein diet ideally contains a limited number of allergenic ingredients that are also new to that individual pet. The term ‘novel’ has a different meaning for each pet because its dietary history is different. In most cases, it is appropriate to exclude common protein sources such as poultry and beef, replacing them with rarer ingredients such as deer or rabbit.

Hydrolyzed pet foods use proteins that are broken down into small molecules that cannot be recognized by the immune system. Enzymatic hydrolysis during the manufacturing process breaks down the protein structure into polypeptide fragments, with the goal of minimizing immune stimulation compared with the intact protein. Subsequent ultrafiltration can further reduce antigenicity. While difficult to produce, these veterinary diets provide a highly digestible and allergen-free product.

The decision between a pet food diet containing novel proteins and a diet containing hydrolyzed proteins is often related to the palatability of the diet and the fat and fiber content that is appropriate for the pet patient. Dietary digestibility is considered critical as the integrity of the intestine would benefit from a highly digestible diet.

Dietary treatment of food allergies is often challenging due to the risks of cross-contamination of the food during the manufacturing process and a lack of compliance by the owner.

Beyond the basics: fiber and the microbiome

Fiber content and the ratio of soluble to insoluble fiber also seem to play an important role. Chronic enteropathies primarily localized in the colon often benefit from higher fiber intake to stabilize the colon microbiome, while localizations in the small intestine often respond better to highly digestible, low-fiber diets.

In the colon, bacterial fermentation of dietary fiber promotes the growth and activity of the commensal intestinal microbiota, inhibits the excessive growth of pathogenic bacteria and provides a source of energy for colonocytes. A balanced microbiome ultimately has a positive effect on the immune system, vitamin B and K production, and the creation of an anti-inflammatory environment.

Probiotics

Probiotics and synbiotics (combinations of a prebiotic and a probiotic) are therapies that alter the gut microbiota and influence the host immune response. Probiotics are defined as live microorganisms that, when consumed in sufficient quantities, provide health benefits to the host. Proposed mechanisms of action of probiotics include enhancement of the gut immune response, production of antimicrobial substances and short-chain fatty acids, and inactivation of bacterial toxins.

The gastrointestinal microbiota is considered an important determinant of gut health, and there is increasing information on its role in dogs with chronic enteropathies. In light of these findings, treatments that modify the microbiota are of great interest, including antibiotics as well as prebiotics and multi-strain probiotics. Fecal microbiota transplantation – in which fecal contents from a healthy donor are administered to a pet with chronic enteropathies – is a newly recognized approach in chronic enteropathy patients, and has shown promising results to date.