AUGUST 2017 THE RIDER /17 Leaky Gut: What to do about it!


By Dr. Bri Henderson BVMS MRCVS ACVSMR-resident Cheltenham Veterinary Centre, Caledon, Ontario 905-838-3451


In my June article we touched on hind


gut issues as a cause of reduced perform- ance. This is an emerging area of research and something we are recognizing more frequently in our competitive horses. The concept of “leaky gut” syndrome is well studied in human endurance athletes and this has formed the foundation for equine studies. The impact of physical and psycho- logical stress on the human gut is well de- fined, where an hour of intense physical exercise reduces blood flow to the intestine and longer durations can cause damage to the inner lining of the intestine. In horses, a similar impact has been illustrated in re- search models with risk factors being a high carbohydrate diet, psychological stress, NSAIDs (Non-steroidal anti-inflammatory drugs) and intense exercise. Before we dive into an unhappy gut, let’s touch on the structure and function of a normal piece of intestine! Horses’ stomachs are relatively small,


holding only 8-15L maximum. From the stomach, their food bolus passes into the first part of the small intestine - the duode- num where further digestion and absorption of carbohydrates and fats begins. The small intestine (duodenum - jejunum - ileum) measures 22m in length! Horses’ rely pri- marily on their hind gut for energy as ‘hind gut fermenters’. The caecum (a super sized version of our appendix) is a large fermen- tation vat which kick starts the break down of forage into “short chain fatty acids” as a food source for the large colon. Over the ~3.5m from the caecum to the small colon, a population of microbes and good bacteria break down forage into substances like bu- tyrate (a short chain fatty acid) which can be absorbed and used for energy. In addi- tion to the production of SCFA’s, the large colon is also responsible for water resorp- tion and the final production of manure. On a cellular level, the intestinal cells


are joined together by “tight junctions” which act as the gate keepers to control what is allowed to move in and out of the cells (and blood supply). Specialized por- tals allow the appropriate passage of elec- trolytes, SCFA, water and the the prevention of bacte- ria/toxins from gaining en- trance to the cells and the rest of the body. See Figure 1 Above


For many years, stom-


ach ulcers have been recog- nized as a cause of poor appetite, poor coat quality and a sour demeanour. We are just beginning to grasp the impact of “Inflammatory Bowel Disease” in horses. Colonic ulceration is esti- mated to occur in 65% of sport horses Clues that your horses’ gut is not operating at 100% are similar between stomach and colon ulceration. Often we only see a change in atti- tude, reduced performance, dull coat, weight/top line loss. As the severity of the ulceration


increases,


changes in blood work, fae- cal blood testing as well as more dramatic behav- ioural/physical changes are noted.


Risk factors are simi-


lar for both stomach and colon ulcers with stress (en- vironmental/transport), nu- trition and NSAIDs. When we focus only on intestinal inflammation, we must also consider any long term/re- cent antibiotic use as well as a genetic predisposition (i.e. Food allergy). Human and equine research indicates


the article, nutrition is key. Low non-structural carbohydrates and supplementation with omega fatty acids (flax or soya oil) is the foun- dation. The addition of psyllium and pre/probiotics to the diet can help also reduce the inflammation within the intestine. Prebiotics are often products


which are broken down to psyllium in the small intestine and then fur- ther digested to ‘short chain fatty acids’ like butyrate in the large colon. Comparatively, probiotics are a supplement of the “good bac- teria” that we want to populate the hind gut. Some recent human studies


have demonstrated that the addition of amino acids to the diet can help


protect the small and large intestine from exercise induced inflamma- tion. Glutamine is identified specif- ically as an amino acid which helps to protect the intestinal lining from exercise/stress induced damage. In addition to the nutrition and supple- ments, I believe it is important to manage our horses appropriately and ensure that they get time to “be horses”. Paddock turnout, consis- tent management schedules, hack- ing, and rest periods during the competitive season will all help to mitigate the stress that our compet- itive horses are under. For more information please


contact Bri Henderson at sportsmedvet@gmail.com


Figure 1. Normal versus “leaky” gut from “Alterations in Intestinal Permeability: The Role of “leaky gut” in health and disease” Journal of Equine Veterinary Science, May 2017 (Stewart et al.)


that nutrition is likely the most important key factor in promoting a healthy intestine and preventing “dysbiosis” (disturbance in the microbe population within the gut al- lowing “bad bacteria” to over grow). Diets high in carbohydrate have a spill over ef- fect, where undigested carbohydrate gets into the small intestine/large intestine and is rapidly fermented to acidic/inflammatory products (i.e. Lactate). This creates a drop in the pH of the large colon which can kill off the “good bacteria”. In it’s most severe form, we know this as “grain over load” when a horse accidentally gorges in a grain bin. In this situation, horses frequently de- velop severe diarrhea, sepsis, laminitis and potentially death. When carbohydrate spill over occurs daily on a smaller scale, the re- sult in a low level but consistent damage to the intestinal barrier which damages those “tight junctions” and allows bacterial/toxins and inflammatory products to creep across the intestinal wall and gain access to the blood supply. When stress, regular medications


(NSAIDs) and intense exercise are com- bined with a grain/carbohydrate rich diet,


we create the perfect storm for the develop- ment of an inflamed large colon. These horses often have frequent low grade colic issues that are never well explained or low level episodes of laminitis with no clear cause. Another form of colonic ulceration is “Right Dorsal Colitis” which develops during treatment with NSAIDs and can cause mild-moderate colic signs with no major findings on rectal examination. For ei- ther cause of colon ulcers, an ultrasound examination of the horses’ abdomen is the best bet to begin defining the situation. By measuring the colon wall thickness and looking for clues of oedema within the colon wall we can begin to build a picture of what is happening on the in- side before we see any major changes on the outside (colic, diarrhea, blood work changes). As mentioned earlier in


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