Vet Advice: 6 Common Causes of Diarrhea in Horses (and How to Treat It)

In this post, Jessica Huntington, DVM, from Stephenville, Texas discusses common causes of horse diarrhea and her recommendations to resolve it quickly. Dr. Huntington takes an integrative approach to the equine athlete by combining traditional veterinary medicine with chiropractic care and acupuncture.


Why Does My Horse Have Diarrhea?

Dealing with horse diarrhea is more than unpleasant and messy—it can be dangerous, leading to serious conditions like dehydration and weight loss, even death. An important function of the equine large colon is to regulate the amount of water absorbed in the body. If you have a horse with diarrhea, it may stem from one of these common instigators of intestinal upset.

1.  Stress

Have you ever noticed when you haul your horse, their manure may be a little loose during trailering or even afterwards? This is an example of stress-induced loose manure.

Stress from traveling, prolonged heat, exercise or performance can trigger loose manure. You can expect one to two piles before it returns to normal.

2.  Poor Oral Health

Using their teeth to masticate food, horses break down roughage into small pieces to aid in proper digestion.  When horses have poor dentition, they're unable to properly chew, leading to longer forage length, which could result in equine diarrhea.

This is a good reason to get a dental checkup. Have your veterinarian examine your horse’s teeth to look for a problematic tooth or abnormality that may be an underlying cause of watery manure.

3.  Internal Parasites

Internal parasites have the ability to invade the colon, attach to the intestinal lining and compromise gut function. This decreases digestive ability and can cause loose manure.

To check for internal parasites, contact your veterinarian for a fecal egg count. This will allow them to identify which internal parasites are present and decide what dewormer is best suited for your horse.

4.  Diet

A rapid change of hay or grain, or feeding too much of either, can bring on diarrhea in young and adult horses. When diet changes, so does the bacterium in a horse’s GI tract. If that change is sudden, gut microbiome can be disrupted.  

Diet change should be a gradual process that happens over a period of three to four weeks. During week one, feed your horse three-fourths the amount of regular hay/grain and one-fourth new hay/grain. At week two, feed one-half the amount of regular hay/grain and one-half new hay/grain. Starting week three, feed one-fourth regular hay/grain and three-fourths new hay/grain. By week four, you can now feed entirely the new hay/grain. This slow change will help your equine’s microbiome adjust properly.

5.  Medications

Supplements or medications can also be the culprit of loose manure or diarrhea. For example, a round of antibiotics targeted to kill bad bacteria will also kill good bacteria. This upsets the delicate balance of intestinal flora the GI tract needs to function properly.

If you notice loose manure and your horse is or has been on medications recently, it’s best to call your veterinarian for direction.

6.  Sand

Every day horses ingest incidental amounts of sand from their environment. Small amounts are normal and can usually be easily digested. But if your horse is consuming too much, it can act like sandpaper, irritating and inflaming the gut lining and potentially causing colic and/or diarrhea.

If your equine is fenced in a sandy area, feed out of a large, shallow water tub. By doing so, you are essentially feeding at ground level but not directly in the sand.

If you notice your horse outright eating sand, a mineral imbalance might be present and your horse may benefit from a natural mineral supplement like this one. 

Daily Gold naturally treats diarrhea in horses

What to Give a Horse with Diarrhea

As a veterinarian, I routinely recommend Redmond Daily Gold Stress Relief to my clients as an effective gastric support supplement for horses. It’s an excellent first line of defense to treat diarrhea in horses or aid in helping your horse recover from diarrhea. The naturally-occurring trace minerals in Daily Gold also replace critical electrolytes lost through loose manure.

For remedial use, feed two scoops of Daily Gold twice daily for an average-sized horse. If after seven days your horse still has diarrhea or you notice an increase in loose manure, or if at any point your horse looses their appetite or acts lethargic, contact your veterinarian immediately.

- Jessica Huntington, DVM, Stephenville, Texas


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