Your Guide to Equine Health Care

Foal Diarrhea

I am a new owner of a broodmare who just had her first foal, which now has diarrhea. How serious is it for him?

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Q:I am a new owner of a broodmare who just had her first foal, which now has diarrhea. What can I do about it? How serious is it for him? How do I keep this from happening again?

A:The causative agents for diarrhea can be bacteria, viruses, parasites, or a range of non-infectious agents or conditions such as toxins, lactose intolerance, or "foal heat" diarrhea. Foal heat is due to normal physiological changes in the foal’s gut and usually occurs anywhere from day seven to 12 after birth. Infectious agents that can cause diarrhea include rotavirus, Salmonella, Rhodococcus equi, clostridial organisms, and Actinobacillus. However, when it comes to diagnosing diarrhea, veterinarians often are hard-pressed to pinpoint a specific cause. Also, once infectious diarrhea has been diagnosed in a foal, that foal should be isolated from other foals to prevent spread of the infection.

One of the main factors in whether a foal becomes afflicted with diarrhea is whether or not the foal received enough colostrum, or whether the colostrum was of good quality. Colostrum contains antibodies that fight off the viruses and bacteria the new foal faces in the first few weeks of life. A blood test done by your veterinarian at 12 hours of age will indicate if the foal nursed enough quality colostrum.

The first 18 hours of the foal’s life are critical when it comes to the absorption of colostrum. It is during that window of opportunity that the foal’s gastrointestinal system can absorb the antibodies found in the colostrum. The mare produces antibodies against bacteria and viruses by vaccination or exposure to these organisms in her environment. The colostrum protection is essentially the only protection a foal has against harmful germs. Foals are born with an immature immune system that has to develop for about 30 days in order for it to produce antibodies on its

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Written by:

Roberta Dwyer, DVM, MS, Dipl. ACVPM, is an equine extension veterinarian and professor at the University of Kentucky, in Lexington, where she also serves as director of the preveterinary advising program. She specializes in veterinary preventative medicine.

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