Clostridium in Mares and Foals

Newborn foals are especially susceptible to gastrointestinal diseases such as clostridial enterocolitis, which is characterized by abdominal pain, diarrhea, toxemia, shock, or death without prior signs. While this disease occurs only sporadically, it is highly fatal. Clostridium perfringens is one of the most common species of this organism to cause enterocolitis, but it has several subtypes, some of which aren't pathogenic (disease-causing).

The prevalence of clostridial enterocolitis in foals is unknown, so researchers from Colorado State University set out to calculate the percentage of mares and foals on six farms that shed Clostridium perfringens in their feces. Clostridium perfringens was found in the feces of 64% of foals eight to 12 hours old, and 90% of 3-day-old foals. Only six of 118 foals had negative culture results.

In contrast, only 30-35% of mares at foaling and one to two months afterward, along with their foals, shed the organism. Clostridium cultures were primarily of the subtype A, which is considered the least dangerous unless it contains either the enterotoxin gene or a gene called beta-2, both of which increase its pathogenic potential. Eighty-five percent of the samples contained subtype A, 12% had subtype A with beta-2, and only 2.1% contained subtype A with the enterotoxin gene. Less than one percent of samples contained subtype C, which is associated with bloody diarrhea in foals. The most striking result was the finding that none of the 128 broodmares tested and only one of the 118 foals became ill with diarrhea, which suggests that C. perfringens subtype A is a normal inhabitant of the guts of horses and newborn foals.

Tillotson, K.; Traub-Dargatz, J.L.; Dickinson, C.E.; et al. Journal of the American Veterinary Medical Association, 220(3), 342-348, 2002.

About the Author

Susan Piscopo, DVM, PhD

Susan Piscopo, DVM, PhD, is a free-lance writer in the biomedical sciences. She practiced veterinary medicine in North Carolina before accepting a fellowship to pursue a PhD in physiology at North Carolina State University. She lives in northern New Jersey with her husband and two sons.

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