Understanding their unique roles in equine gut health

By Dr. Wendy Pearson, PhD (Dr. of Veterinary Toxicology)

Nutritional supplements designed to assist in digestion are becoming increasingly popular among horse owners. We’ve all heard about probiotics, but increasingly we are starting to see products claiming to be prebiotics. How are prebiotics different from probiotics, and do they actually contribute to improved gut health?

Probiotics have a well-established role in promoting robust gut health, and work primarily by introducing live cultures of beneficial bacteria into the horse’s gastrointestinal tract. These bacteria include bifidobacteria, lactobaccilus, and eubacteria, and are considered beneficial because they do not participate, to a significant degree, in the pathogenesis of disease. These beneficial bacteria play a vital role in breaking down non-digestible fibres for the production of volatile fatty acids, which are subsequently absorbed by the horse for energy.

Prebiotics, on the other hand, are not live cultures. Rather, they are compounds that are indigestible by the horse, so arrive relatively unchanged at the large intestine. Once there, the beneficial bacteria selectively ferment them because potentially pathogenic bacteria (such as Clostridia, Staphylococcus, Listeria and E. coli) do not have the necessary enzymes. This allows the beneficial bacteria to grow and flourish, and restrict the growth of potentially pathogenic bacteria. In essence, they feed the good bugs and allow them to grow and outcompete the pathogenic bacteria. The most common prebiotics include oligofructose and chicory inulin.

The primary benefit attributed to prebiotic supplementation is the increased population of native lactobaccilus and bifidobacteria in the colon, which reduces activity of pathogenic bacteria, and production of their toxic metabolites. This translates into reduced vulnerability of the horse to gastrointestinal disorders. Furthermore, prebiotic supplementation is associated with increased colonic surface area for absorption of nutrients and improved digestibility of carbohydrates, lipids, and proteins. The effectiveness of prebiotics is not long-lasting after removal of supplementation, and thus they need to be provided as part of the diet on an ongoing basis in order to continue accruing their benefits.

Supplementation with pre- and probiotics is an effective combination strategy for optimizing overall gut health. Together they stifle production of toxic enterobacteria and their toxic metabolites, and allow the beneficial bacteria to flourish. They also collectively contribute to improved nutrient digestibility and can be of great benefit to horses recovering from gastrointestinal diseases, as well as horses that have been receiving antibiotics or other medications that may disturb normal gut microbiology. 

More by Wendy Pearson

Photo: Supplementation with prebiotics and probiotics contributes toward improved digestibility of nutrients and can be of significant benefit to horses recovering from gastrointestinal diseases or horses with disturbed normal gut microbiology. Photographer: Derrick Coetzee/Flickr