HealthWatch: Sand Colic and Plasma
by Amanda Duckworth
Date Posted: 5/19/2009 10:49:42 AM
Last Updated: 5/20/2009 10:41:39 AM
Rarely do we see our horses lapping up sand like it’s some rare commodity. But inevitably horses end up with burdens of sand in their intestinal tracts from grazing sandy pastures or eating off the ground, writes Heather Smith Thomas in the May issue of The Horse.
Sand moves through the digestive tract with food and passes in manure, but it can irritate the intestinal lining along the way. This irritation can lead to diarrhea, weight loss, and colic. If sand accumulates, it weighs down the intestine and can impair motility, hindering proper digestion and function. Reduction in motility hinders passage of sand and leads to more accumulation, and in some cases the slowdown and accumulation cause a blockage.
“Why it becomes a clinical problem in some horses while others seem to carry fairly heavy sand burdens without a problem is still not understood,” said Dr. David Freeman of the University of Florida. “When sand becomes a problem, it is usually in the colon. Sand moves through the rest of the tract fairly quickly. But when it gets to the large colon, it tends to settle out, probably due to motility patterns of the large colon.
“One method to see if a horse is passing sand is to collect some of the horse’s manure and do a swirl test. Pick up a fecal sample with a plastic rectal sleeve, turn it inside out so it contains the sample, pour water into the sleeve, and mix the water with the feces. After you shake it and let everything settle, the sand will gravitate down into the fingers of the glove.”
There are other ways to make a diagnosis. The veterinarian might listen to the abdomen with a stethoscope. Sand will show up on radiographs because it is very dense. Ultrasound examinations aren’t as helpful as radiographs, but they can be used.
While some veterinarians first try to treat horses with accumulated sand medically, some horses require surgery if these efforts to move sand aren’t successful. In situations where you can’t prevent sand ingestion, feeding the horse fibrous products such as psyllium might help. Psyllium tends to swell, pick up sand, and carry it along, moving it out of the tract with manure.
“Psyllium is a laxative, something we borrowed from human medicine,” said Freeman. “It is a high-fiber product that may collect sand and make it easier for the horse to pass it on through the tract, and it may stimulate motility. But horses eat a lot of fiber to begin with. Addition of psyllium may not increase the total (GI) fiber content a lot.”
Psyllium might work in some horses and not in others, and horse owners should not rely on it alone. Additional treatments for sand impaction include mineral oil, magnesium sulfate, and other laxatives.
“At this point we’re still not sure what works best,” said Freeman. “It may vary from horse to horse. Most of the treatments we use are quite safe and not very expensive.”
Surgery, if needed, is usually successful—sand impaction is not a death sentence.
Dr. Siobhan McAuliffe, a veterinarian in Saudi Arabia, reported that administering hyperimmune plasma to foals does not appear to decrease the occurrence of Rhodococcus equi-caused pneumonia, writes Dr. Stacey Oke in the May issue of The Horse.
Previous studies to evaluate the benefits of the administration of such plasma have resulted in conflicting data.
To explore this issue further, McAuliffe divided foals into two groups during the 2005 foaling season. One group was administered hyperimmune plasma on two separate occasions, whereas the second group served as untreated controls.
Of the 80 foals, 47 were positive for R. equi, as deemed by lesions seen on ultrasound and either a positive cytology or culture. Twenty-four horses had been treated with plasma, while the remaining 23 had not been.
Further, there was no difference in terms of severity of disease or number of required treatment days between the groups.
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