Ask a Vet: What is the Most Effective Way to Treat Diarrhea in Foals?

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By: Nathan M. Slovis, DVM, DACVIM, CHT

This article is sponsored by Hagyard Equine Medical Institute.

Diarrhea is among the most common clinical complaints in foals. According to a National Animal Health Monitoring System equine study, diarrhea affects more than 20% of foals within the first six months of life. Although diarrhea is common with enteritis (inflammation of the small intestine), diarrhea is not always associated with inflammation of the bowel.

Before a veterinarian can consider a treatment course for diarrhea, they must understand the mechanisms of diarrhea. Is it malabsorptive or secretory diarrhea? Malabsorptive is the inability of the intestinal tract to reabsorb water and nutrients. Secretory diarrhea results in the hypersecretion of both water and electrolytes into the intestinal tract. In a general categorization, bacterial toxins (Salmonella or Clostridium, for example) cause secretory diarrhea while viruses (such as rotavirus) can result in malabsorptive diarrhea. In severe infections, bacteria and viruses can result in both secretory and malabsorptive diarrhea.

Diagnosing the cause of diarrhea in foals can be difficult because of the myriad of potential causes. Causes of foal diarrhea may be secondary to non-infectious foal heat diarrhea, dietary issues, bacterial infection (Salmonella, Clostridium difficle, Clostridium perfringens), viral infection, parasitic infection, and cryptosporidium. Obtaining fecal samples for either culture(s) or PCR (DNA) testing can be utilized in identification of a specific agent.

While there is no “golden bullet” to treat foal diarrhea, treatment strategies are directed at both supportive care (fluid therapy, nutrition) and treatment for specific infections as directed by clinical and  diagnostic testing. One novel treatment plan currently used as an adjunctive treatment for both viral and bacterial causes of diarrhea is the use of bentonite clay. Bentonite is effective because it bonds to a variety of toxins and prevents the absorption of toxins by coating the intestinal wall. Not all bentonite clay is created equally, but there is an ultra-purified bentonite clay that is available for use in equine patients, like Relieve intestinal absorbent.

That’s why Hagyard Pharmacy carries the best equine health products to supplement your horse & foal health needs – visit or call 859.281.9511 to see what Hagyard can do for you!

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