The answer is probably not what you think. . . . .
One of the most common questions I am asked as an equine vet is “how can I prevent sand build-up in my horse’s intestine?” In the aptly-named sandhills of North Carolina (Southern Pines, Aberdeen, Pinehurst and surrounding areas), we are plagued with sandy soil that can easily make its way into our horses’ GI tracts. Horses pick up the sand when eating hay or spilled grain from the ground. The sand can then accumulate in the intestines, causing colic, weight loss, diarrhea or other metabolic problems and electrolyte derangements.
Horse owners are rightfully concerned about diagnosing and preventing sand-related problems in their horses. I meet people who use wide varieties of “sand preventing” products for their horses, including psyllium powder (Metamucil), psyllium pellets (Sand Clear, Equi-Aid), beet pulp, wheat bran, rice bran, flax seed, mineral oil, chia seeds, and probably some I haven’t even heard of yet! While some people are absolutely convinced of a particular product’s effectiveness, their conviction is often based on the fact that they haven’t had a problem with sand while using a particular product. As a veterinarian (and a scientist), I am always interested in what science can prove. In my opinion, the conclusions of well-designed scientific studies with large numbers of horses far outweigh the experience of one person who simply hasn’t had a problem. . . . yet.
The first question to ask about sand build-up in horses is: “how can we diagnose it?” There are six ways to diagnose sand in a living horse:
1. exploratory surgery- this is obviously not a good option!
2. abdominal radiography (X-ray): This is the most accurate way to determine whether a horse has sand present in the intestine, but requires specialized, high-powered x-ray machines that are usually only available at university teaching hospitals.
3. abdominal ultrasound- using ultrasound to diagnose sand can be accurate, but relies on the veterinarian to be VERY skilled in abdominal ultrasound. The sand is not visible on the ultrasound, so the veterinarian must determine the location of the large colon and its motility rate as compared to normal horses.
4. Rectal palpation (yep, the old arm-up-the-butt trick!)- usually only VERY severe sand impactions/ accumulations can be felt on rectal exams. Also, rectal palpation is not part of a standard exam, and will usually only be performed after a horse shows signs of colic.
5. fecal sedimentation (float)- this procedure involves mixing fresh manure with water in a bucket or a long glove to determine how much sand settles out. There’s a BIG PROBLEM with this though- if a horse has sand in its manure, does this mean the horse has sand accumulated in its intestine, or does this mean that the horse is consuming sand, but is efficiently eliminating it in the manure? To my knowledge, no one has ever shown that fecal sand correlates in any way to sand accumulation in the intestine.
6. listening for sand in the abdomen with a stethoscope- this method has been proven to be 75-100% accurate, and requires only a stethoscope and few minutes to listen to the horse’s belly. The “whooshing” sounds of sand can be easily appreciated, even by the horse’s owner! I routinely listen for sand in every horse twice yearly during vaccine appointments. In my opinion, this is the only practical and accurate method to determine sand accumulation.
So if your horse is diagnosed with sand, or even suspected to have a GI problem associated with sand, what do we do about it? Many different methods of sand treatment/ prevention have been studied since the mid-nineties. In most studies, horses or ponies were administered sand via stomach tube, sandy feed mash or during a surgical procedure, and then different treatments were given to try to eliminate that sand. Here are the treatments, and the outcomes of the studies:
1. psyllium (pelleted or powder)- There have been several studies over the years designed to evaluate the ability of psyllium products to clear sand. Most studies used ½ to ONE WHOLE POUND of psyllium per horse per day (that’s a lot)! Interestingly, even using that large amount, noneof these studies proved any real effect when compared to the control horses (horses who had the same amount sand inside them, but received no psyllium). In one study, the UNTREATED horses actually eliminated more sand than the treated horses!
(note: one study of a very expensive, brand-name psyllium product did show a positive result in a very small trial of eight horses. To my knowledge, that result has never been duplicated in a larger study. My personal experience with the product has been dissapointing)
I think its also worth mentioning the many dosing schedules for psyllium products (Metamucil, Sand-Clear, etc). Horse owners are often told to administer these products for one week per month, every-other-week, twice weekly, every day, etc. The amounts also vary, but usually range from one ounce to one cup. These amounts are a far cry from the one pound used in scientific studies (and the one pound failed!), and these schedules are completely made-up!
2. Mineral oil- a few studies looked at the ability of mineral oil (a laxative) to eliminate sand. It was not effective.
3. Epsom salt- Epsom salt (magnesium sulfate) is another commonly-used laxative for horses. One study evaluated the effect of this product (given by nasogastric tube) on sand accumulation- it didn’t work very well by itself.
4. Combination of psyllium and Epsom salt: one study showed good success in eliminating sand by using 1lb of Epsom salt PLUS 1lb of psyllium, given by a stomach tube, daily for seven days. That’s nice, but is definitely impractical and expensive unless your horse is currently sick. I use this method on horses that are already showing signs of colic due to sand.
5. Wheat bran- only one study evaluated wheat bran’s ability to eliminate sand. It was not beneficial, and this was another study where the *untreated* horses actually eliminated more sand!
6. All other products- flax, chia, and other products have never been studied to determine their ability to eliminate sand from the horse’s intestines. Based on all the research of other products, I think it’s highly unlikely that there would be much benefit from these products. Remember, supplements are not regulated by any agency, so they can make any claim they want, from preventing sand to preventing death- but just because they say it, does not make it true!
Chia in particular has been touted on certain internet sites as reliably “sand clearing.” It is important to note that the so-called scientific studies mentioned on these sites are NOT published in any scientific journal, and are only available on the websites of the companies that want to sell you chia!
OK, so now that I’ve bashed all the commonly-recommended sand-clearing products for horses, its time to tell you what really DOES work! Are you ready?
Studies (and my personal experience too) have overwhelmingly demonstrated that providing 1.5% to 2.5% percent of body weight per day (15 – 25 lbs for a 1000lb horse) in hay (or forage) will produce the best results when trying to eliminate sand from a horse’s intestine. It is important to note that while no one has studied the effect of an equal amount of grass (instead of hay), it would presumably have the same results. Research environments usually don’t have sufficient space to study horses on large, grassy fields, so we are left to observation in this case. Horses on large, grassy fields usually don’t accumulate as much sand, and moving a “sandy” horse to such a pasture may help them eliminate sand.
There is one important exception in my opinion though- the older horse. Many old horses (20-plus years old) are provided plenty of hay or grass, but are unable to utilize it properly due to bad teeth, or other unknown digestive difficulty. These horses are the ones in which I most commonly hear sand during their twice-yearly exams. When I do hear sand in a horse this age that is being provided an adequate amount of hay, I usually recommend that the horse be changed to a commercial Senior grain (Purina, Triple Crown or Nutrena work well), and fed about 6lbs twice daily. These grains are high in fiber and very digestible. Most horses will be free of sand within a few weeks!
The only other important factor in preventing sand accumulation in horses is preventing them from consuming it in the first place! The biggest culprit for sand ingestion is grain dropped onto sandy soil (common in horses fed in the paddock or pasture). The horses then “scrounge” for the remaining grain, and take in the sand. Stopping this process only requires a little creativity. Some excellent solutions include the use of stall mats under feeders (they will need to be swept free of sand a few times per week), hanging feeders on the “wrong” side of the fence, or constantly moving ground feeders to a new spot in the pasture where the grass is thicker (this will probably get old after a while).
So it's simple: use creativity to stop your horse from consuming sand in the first place, and save your money on the commercial sand prevention products. . . . you can put that money toward hay or high-fiber grain when necessary!
If you have questions about this post, or would like a list of references, please email Dr. Kivett at info@FoundationEquineVet.com