Grit Happens: Enteroliths & Sand Colic
- Sep 1
- 4 min read
Sand colic and enteroliths are two insidious culprits in equine gut health, often lurking beneath the surface until discomfort erupts. Sand colic arises when ingested soil accumulates in the large colon, impeding motility and triggering impaction or inflammation. Enteroliths, on the other hand, are mineral concretions that form over time, often in horses fed high-alfalfa diets or living in arid regions. Both conditions share a common thread: compromised intestinal movement. That’s where mucilaginous feeds like chia, flax/linseed or psyllium husk come into play. Rich in soluble fiber, these feeds form a gel-like matrix that stimulates gut motility, binds debris, and helps sweep foreign matter from the digestive tract—offering a gentle, gut-smart solution to a gritty problem.
Enteroliths
Enteroliths are mineral masses (mostly struvite: magnesium ammonium phosphate) that form in the horse’s large colon, often around a foreign object like a piece of wire, a pebble, twine, or even undigested feed. Think of them as the gut’s version of a pearl—layered over time to neutralise irritation.
Large enteroliths can block the intestine, causing colic or even rupture. Some horses carry them for years without symptoms.
Colic clues: Recurrent mild colic, reduced manure output, or sudden severe pain may signal their presence.
Risk factors:
High-lucerne diets
Rich in protein and magnesium—prime ingredients for struvite
Alkaline hindgut pH
Promotes mineral crystallisation
Genetic predisposition
Arabians, Morgans, and Saddlebreds are overrepresented
Foreign bodies
Twine, stones, hair—anything indigestible can be a nucleus
Indoor management
Reduced turnout (stabling) may affect gut motility
Sandy soils
Chronic sand ingestion may contribute
Sand Colic
Sand colic occurs when horses ingest sand or sediment, which then accumulates in the hindgut—particularly the cecum and ventral colon. Over time, this buildup can:
Disrupt gut motility
Cause irritation or inflammation
Lead to impaction or obstruction
We have grouped these two conditions together, because they both involve foreign matter in the gut, and you can help avoid them in the same way.
Practices to avoid ingestion of foreign matter
You can help to avoid both enteroliths and sand colic with vigilance.
Keep all feed bins clean.
If your surface is sandy, feed on mats, slightly raised bins and feed hay in a rack with a tray that collects the dropped leaf.
Make sure there are no fragments of baling twine or other debris that may have been caught up in your hay during baling.
Observe your horse's manure so you can note changes in frequency, colour, consistency, odour and content.
Avoid lucerne-only diets. While lucerne (alfalfa) is a positive contributor to the diet, it should complement other sources of fibre such as pasture, grassy hay and fibre-rich feeds like soy hulls or beet pulp.
You can also help clear fragments or debris in the gut by routinely adding mucilaginous feeds. These are feeds that swell into a gel when water is added.
Gel-Forming Feeds That Support Gut Clearance
These ingredients are rich in soluble fibre, which absorbs water and forms a gel-like matrix in the digestive tract. This gel can help:
Bind and carry out debris (undigested feed particles, sand, toxins)
Slow digestion for better nutrient absorption
Support microbial balance by feeding beneficial bacteria
Improve stool consistency and reduce impaction risk
Supports hydration
Some examples of mucilaginous feeds:
Chia Seeds
Typically fed mixed into damp feed (10–30g/day for a 500kg horse).
Bonus: High in omega-3s and antioxidants.
Flaxseeds (Linseeds)
50g/100g per day
Ideally ground to unlock nutrients.
Benefits: Supports gut motility, coats the gut lining. Rich in omega-3s
Psyllium Husk
Swells dramatically in water, forming a thick mucilage.
The suggested protocol on various websites like this one is to administer psyllium for 5 consecutive days in a month. I couldn't find the original research that supports this protocol.
There are studies that indicate that it has no effect, (this is another one of those horrible studies. They put sand into 12 ponies' guts, had a treatment group and a control group, and then they euthanised them and measured the sand).
This study from 2008 looked at a paraffin drench (remember back in the day when vets used to do a paraffin drench?) administered with psyllium was more effective at moving out sand in the gut than administered alone. It looks like no ponies had to die to find that out. Happy days.
Anecdotally, when we kept our horses on sandy soils on Sydney's Northern Beaches we gave all our horses a mash composed of wheat bran and about half a cup of psyllium every Sunday, and this prevented all further instances of sand colic, when prior to that it was often occurring.
We supply linseed/flax both as whole seeds and as a meal.
We supply a beneficial amount of chia seed for supporting gut clearance in our Chia Trace Mix and also in our Turmeric Joint Mix.
So you can add 'helps prevent $10,000+ surgery for gut debris' to the list of reasons for feeding them!
We currently don't stock psyllium husks, but our wholesalers carry it. We are happy to add it to our catalogue if there is a demand for it. Get in touch if this is something you'd like to see.
More information about enteroliths:
Enterolithiasis | School of Veterinary Medicine
More information about sand colic:
(Note: studies on sand colic turned out to be a bit of a rabbit hole as some studies were being paid for by businesses trying to find evidence for their psyllium-based formulations, and some were about surgery. Generally speaking I would say that if your horse is requiring surgery for sand colic you may have let the condition deteriorate quite a long way before seeking treatment. This research would not be all that useful to the average attentive horse owner observing subtle signs of colic long before surgery became the only option.)
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