By Dr. Elizabeth DeLomba, DVM MBA
The gut is the gateway to the body. Think about it: this circuitous tube with its outpouchings and multi-functional areas, mediates the process of transferring food and other substances from the exterior world to the interior of the animal. An animal’s GI tract is rich with immune cells, diverse organisms both bacterial and fungal and responsible for digestion and nutrient absorption.
With so many functions, when the gut is upset, it is reflected in the health and functioning of other body systems. More evidence is accumulating that the gut has an impact on the severity of allergies, the integrity of the skin as well as brain health.
Critical Factors Affecting Gut Health
- Microbiome: The microbiome, or the microbial population in the gut is individual and highly variable. By populating the gut with “good” bacteria, it may help prevent pathogenic occupation. The microbiome organisms have functions beyond physical occupation or mucosal sited; they generate vitamins and other nutrients. For example: colonic cells rely on propionate, butyrate and acetate production by colonic bacteria for nutrition and reproduction. Chronic intestinal issues are often linked to imbalance of the microbiota. Most colonic bacteria are located in the free and adherent mucus. Dogs with chronic gastrointestinal disease displayed a higher number of direct surface mucosal bacteria and there was evidence of bacterial penetration of the mucosal barrier. This finding reinforces the thought that pathogenic bacteria penetrate the normal protection mechanisms in the gut. The bacteria, fungi and viruses occupy receptors so that pathogens cannot gain access to the enterocytes. Supporting nonpathogenic organisms helps to reduce the populations and promote a more stable population of “friendly” organisms. The microbiome has direct impact on the surrounding tissue as well as further impact in other places in the body.
- Immune defense: Much of the immune system is based in the gut. GALT (gut associated lymphoid tissue) is estimated to make up about 70% of the whole immune system. Most of the plasma cells, which make IgA, live in GALT. The microbiome has a protective effect on the immune system. Studies have shown that puppies who are given probiotics have a greater immunologic response to their vaccines vs puppies not on probiotics.
- Gut Integrity: Increased intestinal permeability due to the breakdown of the tight junctions between enterocytes is blamed on many negative consequences in the body. It can occur due to a number of inciting factors such as stress, NSAID administration, infection, or inflammation. GI integrity loss results in lipids, proteins, allergens and irritants accessing deeper structures as well as the general circulation. The result is basically that antigens that don’t belong outside the gut, like bacterial toxins, incompletely digested fats and proteins get through the gut, and into the bloodstream. The immune system is triggered and you get an immune reaction. This can manifest as allergic skin irritation, joint issues and in people has been linked to some neurologic/behavioral conditions.
- Fiber: Prebiotic fibers are indigestible, but are soluble fibers that feed the microbiome. These types of fibers include inulin, mannanoligosaccharides (MOS) and fructooligosaccharides (FOS). Other healthy fibers including psyllium, that bulk up the stool and help to absorb excess water and normalize transit times. As noted above, fiber not only regulates the digestive process, but also serves as a food source for the probiotic organisms. Colonization of the GI tract by lactobacillus is enhanced when it is administered with FOS (fructoligosaccharides).
- Mucosal protectants: GI supplements may contain plant-based ingredients that when consumed create mucilage. This forms a protective coating for the GI tract decreasing its exposure to toxins and supporting healthy bacteria. These ingredients include slippery elm and marshmallow root.
When dealing with gastrointestinal issues, a multimodal approach consisting of dietary modification, gut friendly supplements and other measures are often necessary to maintain quality of life for the patient as well as the owner.
Dr. DeLomba, DVM MBA is a Senior Veterinary Services Consultant at VetriScience®. She combines extensive clinical experience with 13 years of management in veterinary pharmaceuticals. She has authored over 50 veterinary articles and continuing education courses. Dr. DeLomba earned a DVM in Veterinary Medicine from Michigan State University and MBA from Villanova University.
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