Horses maintained on sandy lands are at high risk for sand colic, especially if they are grazing or fed from the ground. However, the ingestion of dirt can cause problems, too, so horses grazing short pastures, particularly when there are drought periods and fine dirt particles, are also at high-risk. These horses may be helped with psyllium.
Psyllium is the active ingredient in the human product Metamucil. it's primarily used for constipation prevention and release. Because humans have a much shorter large intestine and more limited ability to ferment fiber, psyllium results in a softer and more bulky stool because the mucilage holds water and is excreted largely intact.
In horses, psyllium is primarily used to assist in the removal of sand collections in the intestinal tract. Two formal studies have now found there is substantially more sand passed in psyllium-treated horses compared to no treatment or mineral oil alone.
Psyllium seed husks, commonly referred to simply as psyllium, are the outer coating of seeds from plants of the genus Plantago. They are high in soluble fiber, which form a gelatinous mass in water.
Psyllium is also useful as a prebiotic. After a few days of use, the fiber-fermenting organisms in the horse's large bowel will adapt to using psyllium as a food source. Fermentation of psyllium in the colon increases the production of butyrate, the major source of energy for the intestinal lining cells. This can help heal inflammatory bowel disease or other lesions in the colon. Because of these effects, psyllium is often a useful addition to the diet for horses with chronic diarrhea.
Psyllium can also be useful for horses prone to choke. Psyllium mixed with water and added to meals has a lubricating effect.
A quick review of the information in our product chart will show you that manufacturer dosing suggestions for psyllium-containing products can vary quite a bit. When treating horses with known high-sand burdens, the suggested dosages from the literature are at least a pound per day for up to 5 days. As mentioned, since the horse's internal fiber-fermenting organisms will eventually adapt to this new ?food,? prolonged feeding of psyllium is not likely to be effective.
Most of the research has been done with horses that had large sand burdens and were actually showing symptoms. However, it certainly makes sense to try to regularly remove sand from horses that are at high risk. While research has shown psyllium is effective in removing sand, only the large doses have been tested. Since the interior of the colon is a very large place, it makes sense that 4 to 8 oz. (25 to 50% of the sand-colic dose) would be a good starting point. Feeding this for 5 days out of the month should be adequate, unless your veterinarian recommends more frequent treatment. The rapid cycling (3 days on, 3 days off, back on again) recommended on some products may be too short to prevent the organisms from adapting.
If using psyllium for beneficial/prebiotic intestinal effects or to help lubricate meals, you feed it daily. Two ounces per day should be adequate for this purpose.
Note: These are all dosages for an average-size horse, 900 to 1,100 pounds. Smaller equines should get less (e.g. half dose for 500-pound pony) and larger horses more. However, if the horse weighs more only because of body fat, there is no need to increase the dose. Dose the horse according to what his ideal, healthy weight would be.
Many equine products suggest you must never get it wet. The rationale behind this is unclear, and it's the opposite of instructions for use of human psyllium laxatives. We feed psyllium after wetting it with enough water to form a gel.
Pure powdered psyllium is light. An ounce by volume/cup measure actually only weighs about half an ounce. Dosing information in this article refers to weight, not volume. Follow manufacturer instructions for commercial products.
In addition to costing more, unless pellets are well chewed, they're much slower to come apart so that they can form a gel. Sand can also accumulate in the small intestine. Since the transit time from stomach to the large intestine is only 4 to 6 hours, we want the psyllium ready to work immediately, so we prefer to feed a powder, mixed in water.
There is certainly no shortage of products containing psyllium, both powders and pellets. Some have additional ingredients, primarily for flavor, and others are pure psyllium. The other ingredients do not add to the effectiveness of psyllium, and we prefer the pure psyllium husk powder.
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Article by Eleanor Kellon, VMD, our Veterinary Editor.