Recently the term Leaky Gut Syndrome (LSG) has been mentioned more and more in articles about equine health. It has even been linked to laminitis by well-known foot researcher, Dr. Chris Pollitt. But it still remains little known by many horse professionals, including veterinarians.
LSG is the name given to a state of gastrointestinal (GI) health where such severe inflammation occurs that the water-tight boundaries between the cells that line the GI tract (mostly the intestinal section) are compromised, thus allowing the toxins in the gut access to the body. Research is showing that the gastrointestinal tract is actually a very complex ecosystem. Similar to other small ecosystems, not only is its importance misunderstood or underestimated, but so are its individual components. LSG includes:
-- Dysbiosis (abnormal populations of gut microbes)
-- Putrefaction of proteins (essentially breakdown by rotting rather than digestion)
-- Fermentation of carbohydrates (leading to creation of toxic and carcinogenic chemicals)
-- Decreased healthy bacterial populations (allowing for further invasion by pathogens such as yeasts and worsening dysbiosis)
-- Sensitization to antigens
LSG is important because we are now starting to recognize the complexity and importance of the gut ecosystem. Like the complex ecosystems that surround us, the small one within has many parts that are symbiotic and interdependent; failure of one part affects those around until eventually the ecosystem falls apart. In regards to the gastrointestinal system, besides digestion, one of its most important jobs is to extract ingested and metabolic toxins (present in the gall bladder as waste from liver metabolism) and to prevent the body from exposure to those toxins. If this ecosystem of a milieu of microbes, enzymes and food breaks down, then diseases such as inflammatory bowel (colic), maldigestion and allergies occur. Allergies are thought to occur when the waterproof barrier allows large molecules from the gut to leak into the lymphatic and circulatory systems. Antibodies to GI microbes have been identified in lungs, joints and skin.
There are probably many causes of LSG, but one of the most important has been understood for many years...antibiotics. The effect that antibiotics have on the normal bacteria of the body has been known since the first use of an antibiotic; however, it has been assumed that the body recovers on its own and the damage to normal bacterial populations is an inconsequential thing. Unfortunately, time and sick people (and animals) are proving that assumption wrong. Research in Europe has shown for people that as little as two doses of an antibiotic in a lifetime can set someone down a LSG pathway. Other factors include environmental factors (ingested toxins, stress) and diet (quality and quantity of fibers and likelihood of reinoculation with healthy bacteria). However, other ingested drugs are also known to change gut bacterial populations including non-steroidal anti-inflammatories (NSAIDs) such as Banamine, phenylbutazone, aspirin, etc.) and steroids.
Don't think that just because you have never given your horse antibiotics that you are home free and clear. A recent government study reviewing water quality has shown that the antibiotic triclosan present in many 'antibacterial' hand soaps is not removed by water treatment plants. The levels shown in many municipal water systems were enough to kill microbes just as efficiently as any ingested antibiotic. (These water systems also showed relatively high levels of hormones such as thyroid, estrogen, progesterone and cortisone due to the human consumption...these too are not removed from water treatment systems.) So your animal's daily drinking water may actually be dosing with antibiotics daily.
Diet, of course, is a very important factor in LSG. Normal populations of GI bacteria live not only on the way to, but also in, the lumen, or opening, of the gut. There are also different populations depending on what part of the gut you are in. All those insoluble fibers that your doctor tells you to eat are just as important for the horse. Those fibers are critical for maintaining healthy bacterial habitat, so to speak. All those donuts you might eat and the sweet feeds and processed pellets with molasses you feed to your horse only feed yeast. Some yeasts are necessary to have, but it is common in people, and is suspected in horses, to have overgrowth of pathological yeasts. Yeasts prefer digesting simple sugars, so feeding too much of those foods feeds the bad yeast, especially if there are insufficient amounts of the other factors that support healthy bacterial populations.
So what can you do about LSG? Be informed and smart about factors in your animal's environment that could alter GI health. Have you given antibiotics lately? Is your horse on bute or Banamine for arthritis or performance pain? Does your horse have access to good pasture or quality roughage or is he on pellets and preprocessed feeds? Consider it all and take corrective actions. Sometimes antibiotics are necessary for fighting an infection...don't panic, just take steps such as giving your horse quality probiotics for at least 30-60 days after a 10 day dose of antibiotics. Make sure that your animal has access to water uncontaminated (hopefully) by agricultural runoff or other chemicals. Provide plenty of quality hay that has good stem (when I select my alfalfa, I look for stemmy hay, not leafy hay) and fiber. If your mare has had a lot of antibiotics in her lifetime, make sure she is on probiotics before she foals; it is her responsibility to inoculate her foal with the proper GI bacteria at birth and if she doesn't have the right stuff, neither will her baby. Avoid too much sweet feed or feeds with sweeteners; avoid extruded feeds due to lack of roughage or heat damage of nutrients. Be conscious of subtle changes in your horse's health and, even if symptoms are a long way (both distance and time) from any GI problems, don't forget its possible role in health and disease.
Kimberly Henneman, DVM, has authored several articles in national equine magazines and is a popular speaker and lecturer. She is director of Animal Health Options, LLC, and director of Choices in Health, LLC. Dr. Henneman graduated Magna cum laude from Utah State in 1981 and is a 1986 graduate of Purdue University School of Veterinary Medicine. She was IVAS certified in veterinary acupuncture in 1990, and AVCA certified in veterinary chiropractic. She is also certified in veterinary homeopathy by the Academy of Veterinary Homeopathy, and certified in Veterinary Chinese Herbal Medicine by the International Veterinary Acupuncture Society. Contact info: Kimberly Henneman, DVM, 150 Starview Dr., Park City, UT 84098