Psyllium (Plantago) Husks are the thin outer coating on Psyllium Seeds and are rich in a form of soluble fibre called mucilage.
Large doses of Psyllium Husk form a gel in the intestines and can be used to help horses move sand out of their digestive tract. However, it only works when used for a few days at a time. If used for a longer period it becomes a prebiotic and the intestinal organisms will adapt to its presence and begin to efficiently break it down.
An added bonus is that wet Psyllium gives a distinctly slippery/slimy coating to a meal which makes it easy to swallow. For this reason, it can also be a useful feed ingredient for horses that suffer from Choke.
Psyllium is the main ingredient in the human product Metamucil, commonly used for constipation. Humans have a much shorter digestive tract and colon than the horse, which is why when used by people, Psyllium can help move and unblock the bowels. Because we can't ferment fibre like the horse can, the mucilage swells and holds water making the stool easier to pass.
According to Dr Eleanor Kellon, a nutraceutical specialist in the US, 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 diarrhoea.
This depends on why your feeding it, as well as the bodyweight of your horse.
If you feel your horse needs some help removing sand from the intestines, then doses up to 450g/day for the average 500kg horse have been suggested, however we feel that as a preventative and as an addition to your regular routine, then a dose of between 100-250g/day for 5 consecutive days a month. Adjust dose according to bodyweight.
If using it for the beneficial/prebiotic intestinal effects or to help lubricate meals, its best fed daily at around 50g/day.