Ridding Sand from the Diet
by: Nancy S. Loving, DVM
In specific regions of the United States, one of the most commonly encountered forms of colic is "sand colic." This is not solely a problem in geographic areas with obviously sandy environments. Anywhere there is sand, decomposed granite, or gravel, "sand colic" can develop. Some farm owners spread sand or road base over their paddocks or arenas to improve the footing, creating a scenario that could lead to sand ingestion.
As grazers and eaters of material directly from the ground, horses ingest dirt and sand each day unless they are fed on mats, concrete, or out of special feeders. Not all horses are fastidious in what they eat. Many will pull up plants and swallow the dirt attached to the roots, especially on overgrazed pastures. Others will riffle around on the ground for every blade of grass, alfalfa hay, or spilled grain, picking up sand and dirt in the process.
In the case of sand ingestion, "an ounce of prevention is truly worth a pound of cure." Preventive strategies can pave the way to a healthier horse, and prevent paving of his intestines with sand or gravel.
The Need for Fiber
Horses evolved to eat small, frequent meals of good-quality fiber. Recognizing and fulfilling this need enables you to modify feeding practices to not only prevent sand colic, but to promote the health of the digestive system. Studies have shown that given the opportunity, horses will graze 17 hours out of every day.
As a rule of thumb, a horse on a hay and grain diet normally needs to consume 1.5-2.5% of his body weight or 15-25 pounds of roughage per day for a 1,000-pound horse. Feeding adequate amounts of hay, or feeding at frequent intervals, can decrease aberrant behavior such as licking the ground or dirt eating (also called pica). If lacking in fiber, a horse might seek it out in the form of board fences, weeds, or dirt. A fiber deficiency also limits normal stimulation of the large colon and makes a horse prone to developing gastric ulcers.
One way of limiting the development of any type of colic is to feed plenty of good-quality hay to promote efficient intestinal activity. In addition, careful pasture management assures ample forage so horses are not forced to consume dirt.
To simulate a "natural" feeding routine, provide free-choice grass hay and supplement only hard-working individuals or difficult keepers with alfalfa and/or grain. A diet of free-choice grass hay, a salt block, and clean, adequate water (which is also vital to gastrointestinal health and motility) helps diminish sand ingestion. This uncomplicated diet also reduces the horse's risk of developing laminitis, and eliminates obesity that can lead to the formation of strangulating lipomas (fatty tumors, which can sometimes occur in non-obese horses).
Providing excess concentrate feeds, such as grains, can increase the risk of colic. Abruptly changing the type of hay or grain can also increase the risk of colic. The annual incidence of colic in the United States has been shown to be 4.2 events per 100 horses each year. Any strategies we can implement to reduce this number would be welcomed by the horse community.
Modify your management to conform to the environmental influences of your farm. Check water tanks to see if sandy material is accumulating in the bottom of the tank--this is a signal that your horse's mouth is full of such material, and that it was rinsed out as he drank. Monitor each horse for differences in eating habits, watching out particularly for ones which eat anything or which nibble the ground all day long. For those horses, modify feeding intervals, increase their quantity of roughage, and implement exercise and turnout to curtail boredom. Some horses might need a muzzle to prevent incessant pica.
Modifying feeding systems to keep hay off the ground is an essential management tool for prevention of sand colic. Feed mangers, racks, nets, and tire feeders can be used to minimize spillage of hay onto the ground. However, an overhead feeding arrangement has its own set of problems, namely the potential risk of increased incidence of respiratory disease. This is due to inadequate clearing of foreign material and mold spores from the respiratory tract when the horse is eating with his head in an upward position. Hay is often pulled out of overhead feeders and scattered on the ground before eating. For horses that do this constantly, rubber mats or concrete pads might be useful to keep hay from contacting dirt. Rubber tire feeders also ensure that the feed material stays put. Tire feeders allow head-down feeding habits, and are relatively safe.
Be cautious in using tire feeders around young foals, as there have been cases of foals being trapped inside the tire. Also, the potential exists for a foal to chew on a rubber feeder, accidentally ingesting the material and developing a serious intestinal impaction. Foals are inquisitive and normally taste everything in their environment; they are susceptible to sand colic as early as the first few weeks of life. The markedly smaller diameter and volume of a foal's digestive tract relative to that of an adult horse hastens the onset of clinical signs, such as diarrhea.
Signs of Sand
Several clinical signs might tip you off to the development of a problem from excessive sand ingestion in any age horse. In about 35% of afflicted horses, a persistent diarrhea develops before the onset of painful signs. The sand forms a space-occupying mass that abrades the lining of the intestinal tract, impairing appropriate absorption of nutrients and fluids and slowing intestinal motility. Subsequently, diarrhea intensifies.
In some individuals, the only presenting signs might be depressed appetite and/or weight loss. Performance might suffer because of chronic discomfort or reduced nutrient efficiency. Other horses experience low-grade, intermittent, mildly painful bouts of colic that recur. In the author's experience, sometimes a colic crisis is precipitated during or after riding, possibly because the sandpaper-like abrasion stimulates painful spasms of the intestine.
A recent report from Finland found that sand in the gut was most often identified in the ventral colon, not at the pelvic flexure. The sand does become lodged at the pelvic flexure and transverse colon when it obstructs the colon, causing serious colic. If sand accumulation is excessive, a mechanical impaction obstructs normal gastrointestinal passage of food materials. An immovable impaction allows gas to build behind it, with associated pain from distended segments of bowel. Pain reflexes and spasms around an impaction slow motility while abnormal peristaltic contractions (wavelike muscular contractions that move food along in the gut) can result in a displaced or twisted intestine, although this is rare.
At the site of the impaction, it is possible for the heavy and abrasive nature of the material to erode through the intestinal lining, leading to a ruptured bowel and life-threatening peritonitis (inflammation of the peritoneum, the membrane that lines the abdominal cavity).
Screening Tests for Sand
A simple test can be performed to monitor for signs of impending sand buildup. Take six fecal balls from the center of a fresh pile of manure. Mix this into a quart of water to make a slurry. Once the solid material precipitates out, measure the amount of sand in the bottom of the vessel. More than one teaspoon per six fecal balls is considered abnormal. The presence of any sand is a cause for concern.
Another means of checking for sand is to listen for telltale sounds using a stethoscope that's placed along the abdominal midline at the girth and near the sternum. Sounds of sand are similar to what one hears as a conch shell is held to an ear, or those reminiscent of a roiling surf on a sandy beach. Some equate these sounds to the noise made by slowly rotating a paper bag partially filled with sand.
However, absence of these sounds does not necessarily imply the absence of sand. For "sand sounds" to be heard, the bowel must be heavy enough to be lying next to the abdominal wall, and the bowel must be moving with its contents rubbing across accumulated sand.
Ancillary Diagnostic Tests
Rectal examination of the intestinal tract by your veterinarian does not always reveal definitive information. If a large amount of sand is present in the gut, it can pull the impacted portion of the intestine toward the bottom of the abdomen and out of reach of his/her arm. If any sand or grit is felt in the fecal material, this is significant, but lack of its presence in feces does not guarantee that it is not present in the gut.
An abdominocentesis (belly tap) is a procedure that involves inserting a needle into the abdomen to ascertain fluid character and volume. Sand might be obtained through such a tap as the weight of the sand pushes the intestines along the belly wall, and the needle inadvertently can penetrate the intestine. This is not a technique to be used to diagnose sanding, but if such information is accidentally obtained in this way, it might confirm a tentative diagnosis.
Abdominal radiography can be necessary to positively diagnose sand in the gastrointestinal tract. This procedure requires powerful X ray equipment that is often only available at a university veterinary teaching hospital or a private equine referral hospital.
Any horse which experiences chronic diarrhea, recurrent episodes of mild colic, unexplainable weight loss, or poor performance should be examined by your veterinarian. The key is to diagnose the problem before it becomes too far advanced to rectify.
Psyllium Treatment Controversy
Psyllium is derived from the husk of the psyllium seed (Plantago ovata), and many commercial psyllium products are marketed as aids in eliminating sand from a horse's gut. Some come as pellets, some as powders, and some in both forms.
Psyllium was once considered to be one of the best treatments to move sandy material out of the gut by lubricating it in a gelatinous material. Currently, it's thought to stimulate motility of the bowel and keep fluids in the intestine, helping to move sand along with the water. An illuminating study at Colorado State University used abdominal radiographs to illustrate that only two days of therapy with psyllium resolved chronic diarrhea attributable to sand.
On the other hand, a 1998 study by the University of Illinois examined elimination of sand from the large intestine by feeding psyllium. All 12 horses in the study had sand surgically placed in their cecums. Six horses were fed or stomach tubed with psyllium while the other six (control) horses received none. Their abdomens were radiographed on Days 1, 5, and 11 to compare the control and treated horses for transit and evacuation of sand from the intestines. All were euthanized on Day 11 and the amount of sand remaining in the intestines was weighed.
The study found no statistical difference between the treated vs. the non-treated ponies with the conclusion that psyllium did not hasten the evacuation of sand from the bowels. However, a few points should be noted regarding this study: Veterinarians in different parts of the United States have noted different degrees of success in treating sanded horses with psyllium. It is possible that not all sand is created equal, and it is possible that not all sand/dirt throughout the United States is amenable to psyllium therapy.
The variability in size of the sand grains that collect in the bowel might determine the effectiveness of psyllium as a treatment strategy. The other notable point is that it takes time to clear sand from the bowels, and 11 days might not be an appropriate time frame upon which to base success or failure.
A final conclusion of the Illinois study on psyllium is probably the most telling point: When intake of sand is prevented, the equine large intestine can reduce and possibly eliminate the sand burden it already has.
A Finnish study done in 2001 concluded that laxatives using psyllium alone or with the addition of magnesium sulfate or mineral oil helped eliminate sand from the bowel in 13 of 14 horses studied. The 14th horse managed to eliminate sand from his bowel when he was turned onto grass pasture rather than housed on a drylot with only hay being fed.
To Feed or Not To Feed Psyllium
Feeding psyllium is not harmful in any way, but it is important that you don't offer your horse a continuous diet of psyllium as the microbes in the bowel will start to digest it as a fiber source, and it will lose its effectiveness as a sand treatment. Your veterinarian can help you determine the appropriate amount of psyllium to feed.
Because sand builds up over a long period of time, a lengthy time might be necessary for it to pass. Recommendations for treating large sand accumulations in the colon include stomach tubing with psyllium for two to five days, followed by feeding a half-pound twice a day to adult horses, or a quarter-pound twice a day to foals. This regimen should be carried out for four to five weeks. Sand will be found inconsistently in the feces during psyllium therapy, so treatment should not be prematurely discontinued.
An alternative is to have Epsom salts (MgSO4) administered via stomach tube daily for three days, then repeated after five to seven days if needed. This saline laxative will increase water in the intestine and is also effective in flushing out the sand in the colon.
For years, many veterinary practitioners have suggested that their clients implement a monthly psyllium preventive plan, and this has resulted in a notable reduction in the incidence of sand colic.
Contrary to popular mythology, wheat bran is neither a therapeutic nor preventive for sand colic. Due to the peculiar anatomy of the equine intestinal tract, by the time the relatively small amount of bran reaches the large intestine of the horse it has little laxative effect.
Do not be lured into a false sense of security by feeding psyllium or any other laxative to your horse(s). Instead, employ proper management strategies to limit the sand burden in your horse's gut in the first place.