Smectite: Diarrhea-Fighting Clay
Di-tri-octahedral smectite is a type of clay, but it's not just any old clay - it has some useful properties that may be able to help prevent or treat certain intestinal tract diseases. The main benefit of smectite is it's ability to bind to bacterial toxins. Bacterial toxins in the intestinal tract play an important role in intestinal diseases, particularly diarrhea. We previously showed that smectite effectively binds to toxins produced by Clostridium perfringens and Clostridium difficile, two important causes of diarrhea in horses, as well as endotoxin, another important bacterial toxin. These studies were done in a lab. While smectite has been widely used for the treatment of diarrhea (or prevention in some situations), we've been using it based on the hope that what happens in the lab also happens in the horse, and on our clinical impression that it seems to do something helpful.
Now, we have a little more actual proof that this is the case. A recent study published in the Veterinary Journal (Hassel et al 2009) looked at the ability of smectite to prevent post-operative diarrhea in horses that underwent colic surgery. Horses were randomly assigned to receive smectite (500 g/500 kg body weight in 4 litres of water, once a day for 3 days) or a placebo (4 litres of water, once a day for 3 days). Treated horses had a significantly lower risk of post-operative diarrhea: 11% versus 41% in controls.
Surprisingly, there was no mention of whether treated horses had a higher survival rate, shorter hospital stay or other important outcomes. It would be useful to know these things, because if smectite just prevents mild diarrhea (i.e. the type that just results in loose feces for a couple days) but doesn't actually improve survival, decrease serious disease, shorten hospitalization or reduce complications, then it's not as useful.
So, we have more evidence indicating that smectite can have a beneficial effect in the horse, not just in the lab. Considering it's safe to use and not excessively expensive, and given that diarrhea is a serious problem in horses, continuing to use it makes sense. Nonetheless, more information about the ability of smectite to have an impact on survival, hospitalization, treatment costs or other factors is still needed.
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