Powder Fights Best Against Sand Colic

Psyllium is most often recommended as a preventative or treatment for sand colic. Sand colic is caused by sandy soil that the horse ingests while grazing or eating from bare ground. The sand builds up inside the large intestine. The contents of the horse’s large intestine are watery until the most distal ends of the intestinal tract, when most of the water is reabsorbed. Because of its weight, some of the sand tends to settle out in the slow-moving large intestine rather than all of it being swept along and passed in the manure. As it settles and builds, it causes the horse to colic.

There is still scientific debate about whether psyllium can help after sand has accumulated, but clinical experience suggests it can. Given the huge capacity of the horse’s digestive tract (over 25 gallons in the cecum and large intestine alone), it’s hard to believe that even the one to two cups of psyllium recommended for treatment of sand colic would make much difference, but this approach is often successful.

Horses who routinely eat off of dirt-filled areas may ingest sand, causing a buildup in the intestine. When the grass in a field is thin, the chances of the horse ingesting dirt increase. Preventing sand colic is one of the best uses for a hay bag.

An article in the March 2001 Equine Veterinary Journal, from the veterinary school in Helsinki, Finland, described nonsurgical treatment of foals and full-size horses with sand colic. Most responded within two to four days to psyllium alone. A few required both psyllium and high doses of magnesium sulfate as a laxative, with or without mineral oil. Food impactions in other areas of the abdomen interfered with the treatment so that must also be ruled out. One horse in the series didn’t respond to treatment but did eventually clear the sand when turned out on pasture.

Diagnosing Sand Colic

Early signs of a problem with sand accumulation can be rather vague. The horse may just seem more depressed or lethargic than normal, rather than obviously colicky. Appetite will eventually lessen, the horse may lose weight, diarrhea or fluid around formed manure may be seen, and eventually there will be some degree of colic.

One screening test that will at least tell you if the horse is eating sand along with its food is to take a few (4 to 6) fecal balls, break them up well and mix with about a quart of water (a large plastic bag works well for this). Allow the mixture to sit undisturbed in an upright position. Undigested fibrous material is light and will float to the top, while sand will settle to the bottom. Any more sand than a teaspoon or so is considered to mean the horse is eating a significant amount of sand.

However, the test isn’t perfect. The amount of sand in the manure does not correlate well with how much is accumulated in the intestine. All it really tells you is that the horse is indeed taking in sand.

Rectal exams don’t help either because the sand collections are out of reach. Listening to the abdomen with a stethoscope may find that the sounds are unusually fluid-like, but this isn’t specific for sand colic.

By far the best way to diagnose sand colic is with radiographs of the abdomen. Even with a large horse this can be attempted at the barn with your vet’s portable X-ray equipment and some angled views through the lower abdomen. The detail won’t be good because of the size of the abdomen, but since the sand contrasts so much with normal tissue it may still be visible. If this fails, the horse will need to go to a full-service clinic.

What To Do

If dealing with a sand collection, don’t expect results from psyllium overnight. Just like food impactions, sand can take several days to clear. The horse may need flunixine (Banamine) to control the pain during this time and, if not eating well, will probably need to be tubed to provide fluids and electrolytes. Surgery is an option if the horse doesn’t respond, and it has a better prognosis for full recovery than other colics.


As always, an ounce of prevention is worth a pound of cure. The best way to prevent sand colic is to prevent the horse from eating sand-contaminated food. Using large rubber mats at outside feeding areas is a good place to start. If necessary, use hay nets, cloth feeders or racks with closely spaced slats to prevent the horse from pulling large amounts of hay onto the ground and ingesting sand. Horses observed to actually eat mouthfuls of dirt or sand (this is unusual) should be fed inside and muzzled when turned out.

Using Psyllium

Psyllium can also be used as a preventative. Regularly scheduled psyllium feeding can help clean out sand in the intestines before it has a chance to accumulate to a dangerous extent. Daily feeding should be avoided, because the organisms in the horse’s intestine can readily adapt to fermenting the soluble fiber in psyllium, making it lose its effectiveness.

Psyllium powder is lightweight. A one-ounce scoop by volume weighs about a half an ounce. For prevention purposes, it is usually recommended that 2 to 4 oz. a day (?? to 1 cup by volume measure) be fed for a week, once a month.


Psyllium works best if there is plenty of water available at the same time. When premixed with water, psyllium forms an oozy goo that doesn’t look at all appetizing, but most horses will readily consume it mixed with their regular feed, or in some cases even plain. If the horse is already symptomatic with sand colic and not drinking well, it is definitely best to prehydrate the psyllium.

Bottom Line

Although it hasn’t actually been confirmed by studies, it is believed that psyllium, because of the high mucilage content, is the preferred form of soluble fiber for treatment of sand accumulations because it will ”trap” and suspend the sand. The herbs Slippery Elm and Marshmallow are also high in mucilage, but they cost considerably more.

You’ll have a choice of powders or pellets. We prefer powders because we have found they are superior in how easily they form a gel. In the powder category, pennies separate the producs in our chart with the lowest being Herb-N-Horse. Horse-Tech’s powdered psyllium has added flax seed, which is a benefit for most horses, but it costs more. If you want the flax, you’ll find that the product does form an excellent gel.

If your horse absolutely will not eat psyllium powder, dry or rehydrated, with or without flavorings, the Equus International pellet, which also contains wheat mill run and anise, would be a good one to try and there may be some additional laxative effect from the wheat.

If you’re not dealing with sand problems and looking to increase soluble fiber in a picky eater, Select the Best’s Fiberpsyll with a blend of psyllium, beet pulp and wheat bran should get the job done.

What did you think of this article?

Thank you for your feedback!