Chronic Diarrhea & Digestive Health

By: Dr. Lydia Gray

SmartPak strongly encourages you to consult your veterinarian regarding specific questions about your horse's health. This information is not intended to diagnose or treat any disease, and is purely educational.

Brief Description

Diarrhea is defined as an increase in the frequency, volume or fluid content of stools. There can be two forms of diarrhea – acute and chronic. Acute diarrhea in a horse can be very serious and should be treated as an emergency. Diarrhea that lasts more than two weeks is considered chronic and can have many causes, such as:

  • Bacterial infection
  • Intestinal parasites
  • Abrupt change in diet
  • Inflammatory bowel disease
  • Disruption to the beneficial bacteria that live in the gut
  • Sand
  • Altered organ function such as heart or liver failure
  • Cancer
  • Unknown

Supplements that May Lend Support

It is generally thought that diarrhea in horses is a result of malfunction in the colon or hindgut. Therefore, supplements that contain ingredients intended to support healthy hindgut function may be helpful, including:

Possible Diagnostic Tests

In addition to a complete physical examination and bloodwork, your veterinarian may perform a number of fecal examinations, including culturing for bacteria, counting parasite eggs and looking for the presence of sand. Additional tests such as rectal palpation, abdominal ultrasound, “belly tap” and others may be performed. Absorption tests and intestinal biopsies may also be helpful but are more difficult and costly to perform.

Prescription Medications Available

If a specific cause for the diarrhea can be identified, such as parasites or bacteria, then appropriate treatment can be given, such as dewormers or antibiotics. However, many times treatment for chronic diarrhea is simply supportive in nature: keeping the horse hydrated, replacing nutrients that may be lost in the stool, and controlling pain and inflammation. Corticosteroids or non-steroidal anti-inflammatories (NSAIDs) are occasionally used for these purposes.

Other Management Suggestions

Your veterinarian may recommend changes to your horse’s diet if he or she feels the hay and/or grain you are currently feeding are contributing to the diarrhea.

Questions to Ask Your Veterinarian

  • What do you believe is the cause of my horse’s diarrhea?
  • Could this be contagious to other horses or to me?
  • Should I take my horse to a referral center or veterinary teaching hospital for a complete diagnostic workup?

Additional Resources

Further Reading for You

From the SmartPak Ask the Vet Blog:
What to Do about Horses with Diarrhea
From The Horse Journal:
  • Chronic Diarrhea Stinks
  • Diarrhea in Horses

Further Reading for Your Veterinarian

Taylor SD, Pusterla N, Vaughan B, et al. Intestinal neoplasia in horses. J Vet Intern Med. 2006 Nov-Dec;20(6):1429-1436.

Plummer PJ. Malabsorptive maldigestive disorder with concurrent Salmonella in a 3-year-old quarter horse. Vet Clin North Am Equine Pract. 2006 Apr;22(1):85-94.

Stampfli H, Oliver OE. Chronic diarrhea and weight loss in three horses. Vet Clin North Am Equine Pract. 2006 Apr;22(1):e27-35.

Barrett EJ, Blair CW, Farlam J, Proudman CJ. Postdosing colic and diarrhea in horses with serological evidence of tapeworm infection. Vet Rec. 2005 Feb 10;156(8):252-253.

Merritt AM. Adult Equine Diarrhea Workup, in Proceedings. 45th Annu Conv Am Assoc Equine Pract 1999;45:276-279.

About Dr. Lydia Gray

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Mollie and Eden
I started riding when I was 9 years old and quickly got swept up into the competitive hunter/jumper world. I showed my first pony, Chloe, in the Small Pony Hunter divisions were we competed at shows like Fairfield Hunt Club, Old Salem, HITS, and West...

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