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Dysbiosis (Part 2)

The equine micro biome is a vast and complex topic that is still being heavily researched.  We've all heard that we should ride a horse from "back to the front" and the more I've come to understand the equine micro biome the more I agree. By overlooking dysbiosis we may be inadvertently missing an opportunity to effectively treat gut related issues.


Equine Dysbiosis: Answering some of the questions posed in Part 1

How are pesticides and chemicals impacting the micro biome of the horse?

Glyphosate: (i.e. Round Up)  While we do not have studies done specifically with horses, we do have information from tests done on humans and other animals that inform us about the impacts of glyphosate on bacteria in the digestive tract.  Glyphosate, patented as an antimicrobial (Monsanto Technology LLC, 2010), has been shown to disrupt gut bacteria in animals, preferentially killing beneficial forms and causing an overgrowth of pathogens.  “Evidence of disruption of gut bacteria by glyphosate is available for poultry (Shehata et al., 2013), cattle (Krüger et al., 2013), and swine (Carman et al., 2013). Salmonella and Clostridium  are highly resistant to the adverse effects of glyphosate, whereas Enterococcus, Bifidobacteria, and Lactobacillus are especially susceptible and die off when exposed to glyphosate.”In other words, glyphosate in/on food your horse eats will have an impact on the health of their hind gut. Glyphosate kills beneficial bacteria and creates an environment that allows pathogens to bloom.  When this occurs you have dysbiosis.

2,4-D  2,4-D is a weed killer that has been linked to a number of negative health effects—including decreased fertility, higher rates of birth defects, and other signs of endocrine disruption in humans.  Animals fed 2,4-D also had decreased fertility  signs of endocrine disruption and high rates of young with bone deformities.  

Despite concerns about potential health risks, in 2014 the U.S. Environmental Protection Agency approved the combined use of 2,4-D and glyphosate. The combo is called Enlist Duo.  It is used mainly on large scale production farms, where it is sprayed on genetically modified crops called Enlist soy and Enlist corn that have been engineered to be resistant to the poisons.  There are government regulations related to "allowable" residue levels for livestock feeds but those levels are much higher than they are for food-stuffs produced to move directly into the human food supply chain.  

The U.S. Department of Agriculture estimates that by 2020, the use of 2,4-D on America's farms could rise between 100 percent and 600 percent now that it has been approved as part of Enlist Duo.   

Lignin Sulfonate.  This is not a chemical or pesticide, but is a food additive. I was not familiar with Lignin Sulfonate so I did a Google search.  You can read about it here:   Lignin is the "glue" that holds the cellulose fibers of trees together and is a co-product from the production of paper products.  Lignin is extracted from wood during the pulping process.  The sulfonate is a high carbohydrate additive.  Lignin Sulfonate is most commonly used to control dust on gravel roads and as a binder in concrete.  What is the purpose for it in horse feed?  It is often paired with molasses for use as an antioxidant and pellet binding agent.   

Acid inhibitor's:     When a horse shows signs and symptoms of a sore stomach or "ulcers", we reach for the only drug on the market that is known to treat ulcers in horses: omeprazole.  Omeprazole is a fantastic medication but it is not meant to be used long term and is not meant to be an on-going,  "preventative" treatment.   Concerns about the overuse of this medication and it's links to the development of right dorsal colitis in horses is growing among veterinary practitioners but the trend toward long term and/or frequent use of these products continues to grow.   

How do Proton Pump Inhibitor's (PPI's) work?  Proton Pump Inhibitors work by blocking the production of stomach acid. No acid, no ulcer.  However; decreasing the acid in the stomach limits the effectiveness of protein digestion and nutrient absorption, which may lead to other problems. Dr. Juliet Getty of Getty Equine Nutrition ( believes concerns about the use of antacids are reasonable and Dr. Joe Pagan of Kentucky Equine Research found interesting correlations between calcium absorption and omeprazole.  You can read their comments from the Paulick Report here

NSAID's:  Bute (phenylbutazone) and Previcox are two of the most common NSAID's seen in the equine medicine chest.

The following is from the American Farrier's Journal, October 1, 2017.  If you have not read through their site I encourage you to do so.  It is full of wonderful (free) information from veterinarians, equine nutritionists and other equine professionals who share their knowledge and expertise on a variety of topics. 

Hoof Nutrition Intelligence: Side Effects of Bute For Pain Control  by equine nutritionist and author, Juliet Getty, PhD.  ( 

"Bute (phenylbutazone) is the most commonly used NSAID (non-steroidal anti-inflammatory drug) for pain resulting from injury to the joints and feet. But while you’re relieving your horse’s pain, you may be putting it at risk of developing an ulcer.

Bute functions by blocking the cyclo-oxygenase (COX) enzymes responsible for converting arachidonic acid (a fatty acid) to prostaglandins, some of which contribute to pain and inflammation.

There are two types of COX enzymes, COX-1 and COX-2, which differ in their impact on your horse’s digestive system. COX-2 is the one we want to inhibit because it is involved in producing the problematic prostaglandins. COX-1, however, is a beneficial enzyme that maintains a healthy gastrointestinal lining and also promotes proper blood clotting.

Unfortunately, bute blocks both of these enzymes. This alleviates the horse’s discomfort (because it blocks COX-2), by making the mucosal lining of the stomach more vulnerable to stomach acid (by blocking beneficial COX-1), potentially leading to ulcerations anywhere along the digestive tract.

Bute disrupts the natural surface barrier within the stomach’s mucosal lining. Within this lining is a fatty bilayer made up of two rows of molecules called phospholipids. The outer portion is hydrophilic (attracted to water) while the inner portion is hydrophobic because of its fat content. Because bute inhibits COX-1, it causes the inner hydrophobic barrier to become hydrophilic, allowing acid to permeate the mucosal lining, resulting in ulcerations.

To protect against ulcers, many veterinarians prescribe omeprazole, which goes by the brand names of full-strength GastroGard used to treat ulcers or the lower-dosed UlcerGard to prevent ulcers while the horse is receiving bute.

Omeprazole is a proton-pump inhibitor, which blocks the final step of acid production within the stomach. Since the protective mucus lining of the stomach may be compromised by bute, it becomes vulnerable to acid. Omeprazole reduces the acid content of the stomach, thereby preventing the formation of ulcers.

However, sudden discontinuation of omeprazole can cause a rebound acid effect, at increased levels, making your horse more vulnerable to ulcer formation. Omeprazole can also lead to malnutrition because stomach acid is necessary to start protein digestion and absorption of key minerals. In addition, omeprazole doesn’t protect against ulcers that may show up in the colon."   

What about common ingredients in horse feed and treats?  Wheat flour, wheat middlings, oats, oat flour, and molasses.  Wheat middlings are the by-product of the production of wheat flour.  They are loaded with lectins. In humans these can inflame the gut, cause leaky gut, and disrupt hormonal communication, specifically INSULIN.  Wheat flour is mostly starch and starch becomes glucose (sugar)...which may contribute to insulin resistance.  Oats work the same way.   

Cane Molasses:   Cane molasses in a by-product of the sugar industry and is a common ingredient in horse feed.   Molasses is what gives some popular horse treats their ooey-gooey texture, a rich aroma ,and that distinctive flavor horses (and I) love.  In horse feeds it is used to increase palatability.  It is often combined with Lectin Sulfonate to help bind the other ingredients in the pellet together.   Molasses is inflammatory so it is best to limit the amount your horse gets.  Research does show that elevations in the glycemic index due to molasses in the diet is greatly dependent on the ingredients paired with the molasses.   So, while it is not "bad" to give your horse feed or treats with molasses, you do need to know what else is in the food and moderate their intake.  


Is it possible that just treating for ulcers and not dysbiosis is causing us to miss an opportunity to effectively manage gut pain in our horses? Some of the products in horse feed and current ulcer treatments may even be making dysbiosis worse  

It is topics like these that show me everyday that what you feed your horse matters.  


Click here to read Part 3 where I share where you can get the micro biome of your horse's hind gut tested and explore how simple changes to your horse's diet may bring big rewards for you and for them! 




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