Canine Immunosuppressant-Responsive Enteropathy (Inflammatory Bowel Disease)

A diagnosis of immunosuppressant-responsive enteropathy is made by exclusion and therefore implies:^1,5,7─9 

• anthelmintic, dietary, and/or antibiotic treatments failed to produce satisfactory clinical responses
• intestinal biopsies and histopathology confirmed the presence of inflammation
• glucocorticoid or other immune-modulating therapy resulted in a positive response

Many dogs with chronic GI disorders, including immunosuppressant-responsive enteropathy, present with intestinal inflammation and changes in the gut microbiome, a condition known as intestinal dysbiosis.^10─15 However, it is unclear whether dysbiosis is a cause of the enteropathy or is a symptom of it.^16,17 

Although diet change by itself may produce an inadequate response, nutritional modifications should still be considered as adjunctive therapy for dogs with immunosuppressant-responsive enteropathy. A change in diet may be beneficial because intestinal inflammation is thought to be triggered by interactions between food components, the mucosal immune system, and the microbiota in genetically susceptible dogs.^18,19 Furthermore, malnutrition is common in dogs with chronic enteropathy due to dysrexia, malabsorption, and increased nutrient losses.²⁰ 

The goals of nutritional intervention are to provide a complete and balanced diet that meets the dog’s nutrient requirements, minimizes mucosal inflammation, compensates for maldigestion and/or malabsorption, and helps control clinical signs.

Key Messages

• Nutritional intervention is used as an adjunct to immunosuppressive therapy in dogs with chronic GI signs that fail to respond to dietary management alone or in combination with antibiotic treatment. Common dietary types include:^{8,16,21,23,24} 
  • hydrolyzed protein diets
  • amino acid-based (i.e., elemental) diets
  • novel protein diets
• Diet characteristics and nutrients of concern include digestibility, energy density, fat, protein, cobalamin (vitamin B12), potassium, and water consumption.^20,25 
  • Not every nutrient of concern is relevant for every patient.
  • Nutrients of concern for a particular dog will vary, depending on which clinical signs are present, their duration and severity, and a nutritional assessment.
• Dogs with immunosuppressant-responsive enteropathy should be fed a highly digestible, palatable, moderate- to low-fat, hydrolyzed or novel protein diet that provides sufficient calories to manage impaired digestion and/or absorption of macronutrients (e.g., protein, fat, or carbohydrate), address dysbiosis, and minimize lean body mass loss.²⁶
  • An amino acid-based, or elemental, diet can be fed instead of a hydrolyzed or novel protein diet to provide readily available amino acids and small peptides for protein synthesis.
  • The chosen diet should be fed exclusively for as long as needed.
• Dehydration is a frequent problem in dogs with immunosuppressant-responsive enteropathy, and may be accompanied by electrolyte imbalances, particularly potassium and possibly sodium.²⁰ Dogs with mild fluid deficits can be managed with oral water intake or subcutaneous fluid administration. However, dogs with moderate to severe dehydration should receive intravenous fluid and electrolyte replacement as appropriate.
• GI malabsorption may result in cobalamin (vitamin B12) deficiency in dogs with chronic enteropathies, despite its abundance in canine diets. If testing reveals a deficiency, vitamin B12 should be supplemented, either parenterally or orally.^25,27 
• Increased levels of omega-3 fatty acids, which have anti-inflammatory and immune response-modulating effects, may benefit dogs with immunosuppressant-responsive enteropathy.^26,27 
• Prebiotics, probiotics, or synbiotics may help dogs with immunosuppressant-responsive enteropathy by influencing the composition of the GI microbiome which, in turn, changes the bacterial antigens presented to the intestinal mucosa and modulates the inflammatory response.^25,26 
  • Prebiotic fiber (e.g., soluble or mixed fiber) in the diet may benefit some dogs through increased production of short-chain fatty acids by the microbiota.
• Many dogs with immunosuppressant-responsive enteropathy experience dysrexia and may benefit initially from eating small, frequent meals (e.g., 3 to 6 meals per day). This can help improve nutrient absorption and minimize adverse responses such as vomiting or diarrhea.^25,28 
  • If clinical signs of the enteropathy resolve, a very gradual transition to the dog’s usual diet can be attempted over a 7-day period. 
  • Depending on the suspected underlying cause, some dogs may need to remain on a therapeutic diet.

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