Geophagia is defined as the deliberate practice of eating earth, soil, or clay; i.e. dirt.  While the definition is easily defined the reason(s) for consuming dirt is multi-factorial.  Theories of why horses voluntarily consume dirt range from the horse has a nutritional deficiency to it’s a habit picked up by mimicking other horses.  Most often when a horse seeks out and voluntarily consumes dirt it is in an area where an old salt block was placed.  The horse is eating “dirt” to obtain the salt found there.  Judicious use of a loose salt will usually prevent or at least minimize this problem.

A more common problem seen in horses is the “accidental” or consequential consumption of sand/dirt.  This is often seen in areas where the soil is high in sand content, e.g. coastal areas.  What about other areas of the United States?  Should horse owners be concerned about sand/dirt ingestion?  All soils are comprised of sand, silt, and clay.  Looking at the following illustration you can see that a very large percentage of the soils in the United States contain sand.  This varies from a high of 100% sand to a low of 20% sand.  Loams are comprised of equal parts sand, clay, and silt and are the predominant types of soils in most of the United States.

These are some factors that contribute to the incidental consumption of sand/dirt:

• Feeding on the ground without proper matting to minimize sand/dirt ingestion.
• Overgrazing pasture or range. This can be due to overstocking; having more animals than the area can adequately carry.  Drought and the failure to properly manage the area are often to blame.  Having upper and lower incisors allow the horse to graze “down to the ground”, contributing to overgrazing and sand/dirt ingestion.
• Allowing unrestricted access to grasses when the pasture is saturated with water. On this type of ground the horse pulls up the entire plant and ingest the sand/dirt clinging to the roots.
• Not cleaning hay feeders. In certain areas a large amount of sand is brought in on the hay.

Horses in a large part of the country are exposed to excess sand/dirt ingestion whether it is voluntary or accidental.  What are some management precautions can horse owners do to minimize issues related to sand/dirt ingestion?

• Feed above ground in hay feeders, nets, etc.
• Use mats under feeders.
• Clean feeders of residual sand/dirt as well as other foreign material on a daily basis.
• Use a psyllium product as directed.

How do horse owners determine if their horse(s) have sand in their gastrointestinal tract?  While there are several methods that can be used, two methods are easily done “in the barn”.  You can take a fresh manure sample before it is contaminated with sand/dirt and place it in a small bucket.  Add water and stir the contents to break-up the manure.  Feel for sand in the bottom of the bucket.  Another method is to use an obstetrics glove (OB sleeve) obtained from your veterinarian or feed store.  Put on the glove, pick-up the fresh manure sample and invert the glove as you pull it off.  Add water to the glove and break-up the manure.  If you feel sand in the fingers, then the horse has sand in the gastrointestinal tract (photo 1 & 2).

Although a very large percentage of horses have the opportunity to ingest sand/dirt whether deliberate or accidental, there are some proven ways to minimize the negative impact this can have on their health.

The use of psyllium seed husk is recommended for the treatment and to aid in the prevention of sand accumulation in the gastrointestinal tract.  Psyllium is a soluble fiber that comes from a shrub-like herb, Plantago ovata.  It grows world-wide but it is most common in India.  When the husk comes in contact with water or moisture it forms a gelatin-like mass.  This mass is thought to “hold” sand particles found in the ventral colon and help remove it from the gastrointestinal tract.  Contact with saliva causes the husk to become slick or slimy often causing palatability issues and the horse not consuming the product.  Pelleting the husk eliminates this issue and allows for improved palatability.  Pelleted psyllium is as effective as the powder since the chewing action of the horse breaks-down the pellets so by the time the psyllium reaches the large intestine both the pellet and powder are in the same form.  Use of a quality psyllium product the first 7 days of each month coupled with good management practices will help minimize sand/dirt ingestion problems.

For additional information refer to the upcoming series on geophagia.