Page 105 - October 2023

from the intestinal lumen into the bloodstream, they activate production of cyclooxygenase (COX), which
in turn produces prostaglandin E2
to initiate sickness behaviors. In addition, breach of the blood-brain barrier by inflammatory mediators passing from the intestinal tract to the systemic circulation to the brain may alter behavioral responses to stimuli. A normally calm horse may become hyper-reactive to touch and loud sounds or movements, to display “irreconcilable” behavior.
Villi (fingerlike projections) of the small intestines respond to injury by contracting their projections, which reduces surface area for absorption. In some ways, this creates a protective response while helping with recovery of the epithelial barrier, referred
to as restitution. Less surface area limits the amount of toxins and bacteria transferred from the bowel lumen to the bloodstream. The remaining cells elongate and stretch to cover the basement membrane, further disrupting passage of unwanted substances across the basement membrane. While this is a protective strategy for the horse, the intestines then are not as efficient in absorption of water and nutrients. This can lead to bouts of diarrhea and/or weight loss even in the face of ample groceries. To fully heal
the intestinal epithelium, stem cells need to regenerate and produce new epithelial cells to replace damaged, dysfunctional villi.
SUPPLEMENTS FOR PROTECTION AND HEALING OF ENTEROCYTES (OR INTESTINAL LINING)
A high fiber diet – aka “Dr. Green” – is
often touted as an excellent panacea for many intestinal and behavioral ills. A fiber-rich diet, especially containing green grass, amplifies native production of butyrate (a short-chain fatty acid) by intestinal bacteria during fermentation. Butyric acid (butyrate) is important to enterocyte health for its use by intestinal epithelial cells
as an energy source. Additionally, butyrate markedly increases epithelial cell proliferation and differentiation and improves colonic barrier function. It is also known to down-regulate bacterial virulence. Research is currently being conducted on how butyric acid supplementation can help to maintain integrity of tight junctions in the face of stress on intestinal epithelial cells.
Other nutritional components are important for intestinal epithelial energy support and repair, including amino acids such as glutamine, arginine, threonine, and lysine. Zinc also is beneficial to intestinal healing,
yet no defined studies have yielded concrete information about its role for horses. Selenium and vitamin E may have potential benefits, but studies still need to be pursued.
Protection of the microbiome is an important element to guarding against changes in gastrointestinal permeability. Prebiotics and probiotics may have a role
in nutritional support of the microbiome. However, there are concerns that manufacturers of probiotics list label ingredients that may not actually be included in the bucket as specified. Without FDA oversight on product quality and integrity
of probiotics, there is no guarantee that probiotics will perform as promised.
A fiber-rich diet, especially one containing green grass, amplifies production of butyrate (a short-chain fatty acid) by intestinal bacteria during fermentation.
VETERINARY VIEWS
Research has yielded findings that leaky gut syndrome leads to other manifestations of systemic inflammation, particularly in other epithelial tissues, such as:
SPEEDHORSE October 2023 103
Skin allergies, including pruritus (itching) and hives. Speedhorse Archives
Laminitis – damage and inflammation of the tissue between the hoof and the underlying coffin bone.
Brain inflammation from cytokines that signal the brain to induce sickness behavior such as fever, loss of appetite and lack of energy.