Sand colic is a term for abdominal pain in horses caused by the ingestion of sand.

Depending on the geographic region, five to thirty percent of all colic cases are caused by sand or sediment accumulation in the gut. [1][2][3]

Sand colic typically occurs in dry areas with poor vegetation growth. When horses forage, sand particles and other sediments (such as silt and gravel) are ingested and may remain in the large colon for long periods. [1]

Sand enteropathy or impaction occurs when sand accumulation damages the large intestine, leading to inflammation of the colon wall, distress or complete bowel obstruction. Without medical intervention, impaction colic can be fatal.

Acute colic is a serious condition that requires medical attention. If your horse forages in a sandy region and presents clinical signs of sand colic, contact your veterinarian immediately.

Sand Colic in Horses

When horses ingest sand particles, some of the sediment is cleared via bowel movements. However, sand can begin to accumulate in the ventral colon and cecum of the horse, negatively impacting gut motility (the movement of food through the intestines).

Sand accumulation can lead to weight loss, diarrhea, constipation, stomach distension, poor performance and acute colic.

In extreme cases, obstipation (severe or complete constipation) from blockages may occur, and intestines can rupture. [4]

It is unknown how much sand needs to accumulate in the digestive tract to cause clinical signs of impaction. [5] Signs of sediment accumulation vary depending on the size of the horse, and some horses display no symptoms at all. [6]

Clinical Signs

After ingesting large amounts of sand, horses may exhibit typical colic symptoms, such as: [7]

  • Lack of appetite
  • Distressed or anxious behaviour
  • Pawing at the floor
  • Looking at or biting at the sides of the belly
  • Lying down, standing up, rolling over
  • High heart rate (over 64 bpm) or other changes in vital signs

If your horse displays signs of colic, contact your veterinarian immediately for urgent care. All forms of colic should be treated as a medical emergency.

Why do Horses Eat Sand?

Sand colic is usually attributed to incidental sand ingestion that occurs when horses are foraging in sandy regions. However, some horses may intentionally ingest sand or soil at pasture, a practice known as geophagia.

This behaviour may indicate a nutritional deficiency (such as a lack of selenium or sodium in the diet) or boredom in horses. [6][8] However, further research is needed to understand the factors that cause geophagia.

Both wild and domesticated horses have been observed to return to specific locations to ingest soil repeatedly. They may be seeking out certain minerals in the soil, but site selection does not seem to correlate with soil mineral content. [8]

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Risk Factors for Sand Colic

Several factors increase a horse’s risk of sand colic, including feeding on the ground or in sandy paddocks, housing horses on sandy soils or keeping horses on low-quality pastures. [1]

Horses turned out in sandy paddocks or pastures may ingest soil while searching the ground with their lips for forages. Sand colic is most common in the southern United States (i.e. Arizona and Utah), where the soil is dry and forages are more scarce.

Horses with restricted access to forages or hay could be more likely to colic due to a lack of fiber in the diet. [7] Fiber is critical for gut motility and clearing ingested sand and soil from the digestive tract.

Some breeds, such as the Quarter Horse, Shetland Pony, Miniature Horse and Finnhorse, are believed to be more susceptible to sand colic. This may be related to a higher appetite in these breeds. [6]

Diagnosis

Your veterinarian will conduct a differential diagnosis to rule out other conditions that may be causing symptoms of sand colic. [6]

Clinical presentation of sand accumulation may mimic other diseases or conditions, such as laminitis, tying-up (rhabdomyolysis) or pneumonia. [7]

Horses may experience poor performance, which can be mistaken for Equine Gastric Ulcer Syndrome (EGUS) and treated as such.

Auscultation of the Abdomen

Abdominal auscultation can accurately diagnose sand colic by using a stethoscope and listening for sand sounds in the gut.

Abdominal sounds indicating sand accumulation are gritty and resemble the sound of waves crashing on a beach. [1][6][9]

Sand sounds vary in intensity and duration, depending on the amount of sand accumulated, with large accumulations resulting in more noise. Sand sounds are believed to occur when greater than 6.3 – 10.5 kg of sand accumulates in the colon. [6]

Many veterinarians can identify abnormal gut sounds associated with large amounts of sand in the colon. Coarse sands may produce more identifiable noises, making diagnosis easier.

Fecal Sand Sedimentation

Fecal sand sedimentation is a reliable diagnostic tool for sand colic or impaction in horses.

However, results can be highly variable between individual horses and fecal samples. Some horses with large sand loads do not excrete sand.

Follow these steps to conduct a fecal sand sedimentation test at home on your horse: [5]

  1. Gather a few manure balls from a fresh pile and place them in a plastic bag (avoid using manure that has touched the ground)
  2. Fill the plastic bag halfway with water and squeeze the manure sample to create a mixture
  3. Hang the bag by a corner and allow the sample to settle over several hours

Horses with a moderate to severe sand load in the digestive tract will have a substantial amount of sand settling in the corner of the bag.

If a bag is unavailable, a fecal sand test can be conducted by mixing feces with water in a bucket. [1]

Note that healthy horses who live in sandy areas may pass small amounts of sand in their feces without signs of physical pain. Small sand loads in the gut are common in some geographical areas and are rarely cause for concern.

If a horse shows signs of colic or diarrhea and is passing noticeable sand in their feces, call your veterinarian immediately for examination and diagnosis.

Some horses may also demonstrate clinical signs of colic without passing any sand.

Abdominal Radiography & Ultrasound

The best method to determine the severity of colonic sand accumulations is abdominal radiography. [3][5] Sand and other sediments have a distinct shadow in a radiograph, and grading systems can be used to determine the size of the accumulation. [6]

Radiography can also be used to assess the effectiveness of treatments or supplements for evacuating sand from the gut. [5]

Ultrasonography is generally accurate when ruling out sand accumulation, although it has limited use when diagnosing positive tests. [6] This makes ultrasound an accurate screening tool with limitations for diagnosis.