Dealing With Sand Colic
Sand colic is typically seen in horses that live in dry, sandy areas.
The lulling sound of waves slowly rolling in and out. A nice, sandy beach. Great scenarios vacation-wise, but a crisis in the making when applied to your horse's gut sounds and abdominal radiographic post cards. Diagnosis: Sand colic.
Sand colic occurs when the horse ingests sand along with regular rations into the intestinal tract. "Sand colic is typically seen in horses that live in dry, sandy areas," says Andie Dee, DVM, of B.W. Furlong and Associates in New Jersey. "You can't always hear sand when it's in the intestinal tract, but when you do, you'll never forget it," Dee says. "It sounds like the tide rolling in and rolling out."
"Sand colic is abdominal pain caused by an intestinal obstruction, i.e., an impaction," states George Martin, DVM, Dipl. ACVS, and Professor and Section Chief Equine Medicine and Surgery, Louisiana State University. "In most impaction colics, the obstruction is caused by feed, but in sand colic it is caused by sand."
Dee says that some horses seem to be more prone to sand colic than others, even when sharing the same environment. "We don't know why. It may have something to do with the ability of an individual's intestinal motility to keep things moving along. Or, it may be that one individual tends to pick up more sand than another."
While age is not a factor, weanlings, yearlings, and sometimes nursing foals are more inclined to eat sand preferentially, points out Terry Swanson, DVM, CEO of Littleton Large Animal Clinic in Colorado and a former president of the American Association of Equine Practitioners.
Abdominal distress is the most common clinical sign of early stage sand colic, just as it is for a mild "regular" colic. "There is no clinical sign specific to sand colic," Martin says, "but some horses will develop diarrhea as the primary sign or just before the signs of colic develop." Typically, the horse suffers from inappetence and abdominal pain. The animal also shows signs of being mildly depressed and/or sweaty, has a fever, yawns excessively, adopts a posture to urinate but fails to or urinates very little, looks at its flank or belly, lies down, paws, rolls, or thrashes.
Diagnosis is based on tests, clinical signs, and observation of the environment.
"From a veterinary standpoint, we'll look at the environment," explains Swanson. "Is the horse in a sandy corral or pasture where sand is readily available? Is the horse being fed in an environment where he's picking up feed and sand at the same time? We look for that when trying to establish a diagnosis."
Stool samples are checked for sand. "We take the fecal material, add water, mash it up, then let it settle out for about 20 minutes," says Swanson. The manure "tea" can be mixed either in an ordinary bucket or in a rectal sleeve. If sand is present, it will settle out first because it is heavier. Take caution, however, for sand can be present in a normal horse's feces as well.
Abnormal abdominal sounds might point to sand colic, says Dee. "Typically when veterinarians auscultate (listen to) the abdomen, we listen to four quarters--the upper and lower sections on the right and left sides. But when we're looking for sand colic, we also listen to the ventral midline.
Martin explains how to listen for sand colic. "The process is to push abruptly and forcefully into the horse's lower abdomen with your fist, then listen for the peculiar sound of the sand particles moving in the large colon."
Ultrasound And Sand Colic
Researchers at Auburn University have found that ultrasound could be an effective way to diagnose sand colic. The invasive nature of finding sand in the colon—usually during emergency colic surgery—also might be prevented by use of this method.
According to Debra Taylor, DVM, Dipl. ACVIM, of Auburn University, sand can be seen in the gut as a homogeneous gray pattern, with no heterogeneous texture. The ultrasound waves tend to penetrate deeper into a colon laden with sand, while waves will "pop back" in a horse with gas colic, presenting texture on the ultrasound screen.
"It is difficult to appreciate in a still picture, as there is also movement of the sand; it sparkles as it moves," explains Taylor. "The sand is very homogeneous, all the same texture throughout. Feces would have a light and dark texture."
The sand can be viewed best with a 3.5 megahertz probe, but can sometimes be seen with a 5 megahertz probe. Taylor says that the amount of sand seen with the ultrasound isn't always indicative of how much is in the horse. "If there were only a little sand, you would probably miss it," she adds.
Although the findings have yet to be published in a veterinary journal, Taylor and researchers feel certain they can see the condition. "Our limited amount of research has led us to believe that this is the pattern exhibited on ultrasound by horses that have sand in their ventral colon," says Taylor.
Most horses have some sand in their digestive system. Different horses have different tolerances for amounts of sand, and all gastrointestinal tracts move it through at different rates. Some horses excrete the sand easily, whereas others collect it over the years until they have had one mouthful too many.
"I've examined a rectum where I felt like I had my hand in a sandy beach," says Taylor. Ideally, the ultrasound research of Auburn will help veterinarians catch these sand collectors before their GI tracts are overcome by colic and the problem necessitates surgery.
Stephanie L. Church
Sand also is visible via radiography. "We've X rayed some horses that looked like they had a little beach in the bottom of their large colons!" Swanson reports. Radiographing foals, miniature horses, ponies, and small horses generally is not difficult, but for full-sized horses, abdominal radiography is more difficult, says Swanson, because of the need for larger radiographic equipment.
Occasionally, the veterinarian might perform an abdominocentesis. "We put a needle in the bottom of the abdomen to check the peritoneal fluid surrounding the intestine," Swanson says. "If a horse has a bowel that is smothered with sand, sometimes you can feel sand on the needle. We don't like to use this procedure, but occasionally it is done."
Another diagnostic test is ultrasound. Using a probe along the ventral abdomen, you can visualize the sand as starbursts. There is research in progress at Auburn University exploring the effectiveness of ultrasound for sand colic diagnosis (see sidebar on at left).
"Conservative treatment is ideal when diagnosed early," Martin says. "Administration of a bulk laxative product, such as psyllium (Metamucil), appears to be the most effective. Psyllium is believed to work by stimulating intestinal motility and by agglutinating the sand (making it stick together), allowing the horse to pass the sand. Other laxatives such as mineral oil generally are ineffective because they tend to float over the surface of the impaction. Rehydration and over-hydration with intravenously administered fluids can help add moisture content to the lumen in the area of the impaction."
The impaction will cause many horses to become bloated because they cannot pass the gas. This usually causes severe pain.
Swanson says that antibiotics are sometimes added to the regimen to protect the horse from absorption of bacteria from a bowel that is inflammed by the sand.
"Over the course of several hours, if the horse's clinical signs do not improve, or if they worsen, then surgical exploration is the next treatment step," says Martin. "During surgery, the treatment is to remove the sand from the large colon. This can be done relatively easily, although there can be some tricky aspects to the procedure. Basically, the most moveable part of the large colon is withdrawn from the horse's abdomen and either placed on a sterile tray or hung over the edge of the table. A 15-20 cm incision is made into the colon, and the contents are flushed out onto the floor or into some type of collecting system. (The contents of the colon are filled with bacteria and must not be spilled onto the external surface of the colon or into the abdominal cavity because infectious peritonitis will be inevitable.) After the sand has been removed from the large colon, the incision in the colon is sutured, and the bowel is re-positioned in the horse."
Sand colic can be fatal when it is left untreated, if treatment is initiated too late, or when the condition is very severe. Sand colic usually is fairly mild and responds favorably to conservative treatment. Horses requiring surgery have about a 60%-65% survival rate, says Swanson.
The threat of sand colic can be minimized in high-risk areas by taking a few preventive measures. Swanson offers some suggestions. "Observe your horse to see if he has habits that would cause him to ingest a lot of sand. In other words, is he always nibbling on the ground, rubbing his nose, acting like he's ingesting sand? Feed horses in an environment where the hay leaves fall on a firm surface other than sand. If you're feeding outside in a lot, arrange some way to have a harder surface where the feeder is. If feeding in a stall, lay down rubber matting where the hay is so the horse isn't picking the leaves up out of the sand."
"Allow horses to graze only in pastures with adequate growth so that ingestion of sand is less likely," adds Martin.
In addition, feed horses grain and hay before turnout, so they are not so hungry, and will not rip the grass up with the sandy roots. If possible, turn out horses in the day during the summer, so they will go into the woods and not eat so heartily.
Horses which live in a sandy environment or which have had sand colic before might benefit from preemptive measures via regular feeding of psyllium. "I recommend one to two cups of psyllium per 1,000 pounds of horse daily for a week, every four to five weeks," says Martin. Alternatively, Swanson notes psyllium can be fed one day a week, every week. "I don't recommend every horse that lives on a sandy lot be put on psyllium, but if a horse appears to be nibbling or licking the sand or a stool sample shows an impressive amount of sand when you float the stool, then that's the kind of horse I would put on a prophylaxis."
Swanson warns that psyllium should be fed intermittently, like once a week, rather than continually. "Bulk laxatives seem to have more effect that way," he says. "When used every day, the physiology may adjust to that, and we don't get the desired effect."
While complete control of the factors that cause sand colic aren't possible, smart preventive techniques can reduce the risk of your horse's developing this affliction. Prompt diagnosis and treatment can ensure that a mild colic doesn't become a fatal colic.
About the Author
Marcia King is an award-winning freelance writer based in Ohio who specializes in equine, canine, and feline veterinary topics. She's schooled in hunt seat, dressage, and Western pleasure.
POLL: Colic Surgery