Enterolith: A Common Colic Culprit

Last Updated on August 21, 2023 by Allison Price

Although you may not be aware, a small pebble or a few strands of baling twine could cause colic. Learn more about whether your horse’s diet, habits, or even where he lives can make him more susceptible to this common cause of colic–enterolith.

Horses that ingest bits of baling twine, or other foreign objects may develop an enterolith around them much the same way a pearl surrounds a grain of sand.

Clint said, “He just didn’t look right.” Clint followed his instincts and loaded him into the trailer before he took him to the clinic. He says, “It was a good decision we made, or else we might have lost his.” His veterinarian removed two small intestinal stones during colic surgery. One was the size of an apple and one was the size of softballs. The veterinarian discovered the young stallion’s love for tail hair by examining the enteroliths.

These products may be helpful in colic cases, but they won’t help with enteroliths. Ortho Equine’s Immediate Respond, Say Whoa Gel or Silver Lining Herbs Eaz may be helpful.

After being ingested, the tail hair formed a sphere and mineral deposits, similar to a pearl in an oyster. Clint was alerted to the horse’s discomfort when it failed to pass through his intestinal tract. Although the stallion was able to recover and compete again, his experience with colic highlights the damage enteroliths can cause to a horse’s health.

How common is enteroliths then? How can you tell if your horse may be at risk? We asked Dr. Diana Hassel a few questions about the deadly stones. She studied horse colic and enterolithiasis at the University of California at Davis before joining the faculty at Colorado State University.

Here are her words.

What is an enterolith? How do they form?

An enterolith, in fact, is a stone mainly made of strvite mineral, which is a combination of magnesium, ammonium and phosphate. There are many shapes and sizes of them, but the majority are either spherical (having four sides) or tetrahedral.

Each enterolith contains a center from which the mineral is laid down in concentric ring configurations.

Common “nidi” culprits are usually pebbles, or even grains of sand. However, they can also contain feed material, metal foreign bodies (like a small amount of baling wire), baling twine or hair.

trichobezoars are simple hairballs. However, they are not a common cause of colic in horses. Although they are rare, they can cause severe obstructions that require surgery. However, if enough mineral is placed over the trichobezoar it could become an enterolith with hairball center.

Sometimes, we will see enteroliths from ingested rope and twine all over the surface.

[READ ABOUT Do’s & Do’ts of Colic]

This enterolith can cause colic and intestinal blockages in horses. It must be surgically removed if the horse wants to live.

Are enterolites common?

At the University of California, Davis, enteroliths are the most frequent type of surgical colic. The number of cases seems have increased. Only 6.6 percent of horses who were referred to the clinic because they had colic between 1973 and 1986 had enteroliths. This number rose to 21.6 per cent between 1987 and 1996.

Horses with enteroliths are seen almost every week. Most commonly, an enterolith is a single, small-sized, baseball-sized blockage that has become lodged in the descending colon. They form in the ascending colon (larger) and move downstream to the bowel (smaller diameter). This can cause an obstruction.

What warning signs are there?

15% of horses suffering from enteroliths have had to pass a small amount of enterolith in their manure. It will look similar to a cement fecal ball. I recommend that you have your horse examined at a clinic capable of performing abdominal x-rays if there are any enteroliths found in your pasture. This is the best way to detect enteroliths at this time, although x-rays might not always be able to detect them in larger horses.

About 33 percent of horses suffer from chronic recurrent colic, which responds to medical treatment. This can also indicate that an enterolith may be present.

Other symptoms that are less common include mood changes (grumpiness), changes in performance (downhill riding or jumping may be affected), chronic diarrhea and weight loss (although horses with enteroliths tend to be overweight).

[READ: How to Not Panic If Your Horse Colics]img alt=”Inside view for an enterolith.” data-src=”https://horseandrider.com/.image/c_limit%2Ccs_srgb%2Cfl_progressive%2Cq_auto:good%2Cw_700/MTY0NzMxMzcyMjc4MTMwMjI3/enterolith.jpg” src=”https://horseandrider.com/.image/t_share/MTY0NzMxMzcyMjc4MTMwMjI3/enterolith.jpg”/> 

The cross-section below shows an enterolith that has concentric rings made of minerals over time. The enterolith’s size increases and it is not safe to pass through the digestive tract.

What should you do if your horse is colicked with an enterolith ?

Surgery is currently the only option for treating enteroliths. Horses that have an enterolith causing their intestines or bowels to burst will not survive.

The chances of success are very high if the condition is detected before the intestinal ruptures.

Are horses more likely to enteringoliths?

A combination of three factors is most likely to cause enteroliths in horses: environment, diet, and genetics.

It is a very regional disease that has a worldwide distribution. A few cases have been reported in Australia, Tahiti, as well as parts of Europe. The states of Florida, Texas, Ohio and Texas are the most common places where enteroliths occur in the United States. California has the highest number.

California, for example, has rich alfalfa hay. It is high in magnesium and protein, as well as many other ingredients that are necessary to make a stone. Alfalfa rich in magnesium and protein contributes to a more acidic (higher pH), environment in the colon. Horses that are more likely to develop enteroliths also have a higher pH, even though they are on the same diet as horses who aren’t prone to enteroliths.

Certain breeds are more at risk than others. American Miniatures, Morgans, Arabians and Morgans have been found to be more likely to develop enteroliths. It is not unusual for horses with enteroliths to have their siblings affected as well.

Are younger horses at greater risk?

Horses with enterolith obstructions are usually between 11 and 12 years old. However, they can be as young or old as a yearling. The Miniature Horse was 11 months old when the case was first reported.

To prevent your horse from developing enteroliths again, he should start a more aggressive preventive program if he develops them at an early age.

What is a preventive programme?

Horses with a history of the disease are best prevented by eliminating alfalfa products and allowing them to go on pasture daily.

Switch to grass or oathay and add grain and apple cider vinegar. While vinegar is not proven to prevent enteroliths from occurring, it can reduce the colon pH by a small amount. Although some horses may initially be irritated by the vinegar’s flavor, most horses eventually come to love it. One cup would be sufficient to cover one grain twice daily.

Horses with an enterolith should be closely monitored when their feed is changed. Horses can become constipated if their feed is changed to a fibrous, such as grass hay or oat, which can lead to the stone moving into the intestinal tract. It is best to have abdominal x-rays done if you suspect that your horse may have enteroliths.

You can feed your horse a 50/50 mix of grass and alfalfa if you don’t have a horse at high risk. Alfalfa is generally considered a high quality feed and can be helpful in preventing ulcers. Alfalfa should not be removed from horses’ diets.

Allison Price
Allison Price

I’m Allison, born and raised in San Diego California, the earliest memory I have with horses was at my grandfather’s farm. I used to sit at the stable as a kid and hang out with my Papa while he was training the horses. When I was invited to watch a horse riding competition, I got so fascinated with riding!