Turkish foal study adds baseline data on clostridial fecal findings

A newly published study offers one of the first multiregional looks at clostridial targets in foals from Türkiye, adding surveillance data on pathogens that continue to complicate equine diarrhea workups. Reporting in Veterinary Sciences on October 9, 2026, Burcu Karagülle and Zeynep Yerlikaya examined 300 archived fecal samples from 2- to 6-month-old foals from 20 stud farms in five Turkish provinces. They confirmed Clostridium perfringens in 16.7% of samples and detected Clostridioides difficile marker and toxin-gene targets in a smaller subset, with both organisms represented across all regions sampled. (mdpi.com)

The backdrop here is a familiar one for equine veterinarians: clostridial organisms are well-recognized in foal and adult horse enterocolitis, but interpretation is rarely straightforward. Merck Veterinary Manual notes that C. difficile and C. perfringens are common causes of equine enterocolitis, yet both organisms, and some toxin-producing strains, can also be detected in healthy horses and foals. AAEP guidance similarly emphasizes that bacterial presence alone can be hard to interpret, especially because clostridial bacteria may be part of normal intestinal flora and fecal shedding can occur outside active disease. (merckvetmanual.com)

That context matters for this paper’s design and conclusions. The authors investigated archived fecal material from foals aged 2 to 6 months, with gastrointestinal signs recorded in only 10 animals and no systematic clinical information available for the remaining 290. C. perfringens was identified by anaerobic culture followed by PCR confirmation and toxin-gene profiling, while C. difficile was assessed molecularly from fecal DNA. The study found 50 cpa-confirmed C. perfringens samples, all showing a cpa-only toxin-gene profile among the targets assessed. For C. difficile, 12 samples were positive for the species-associated tpi target, and seven of those also carried both tcdA and tcdB gene targets. The authors explicitly caution that these molecular findings do not establish viable C. difficile, active toxin production, or clinical infection. (mdpi.com)

That caution lines up with broader diagnostic guidance. AAEP says diagnosis of clostridial diarrhea should ideally go beyond organism detection to include toxin-focused testing, including assays for C. difficile toxins A and B and, where appropriate, C. perfringens toxin targets. The guidance also notes that type C C. perfringens in foals is considered abnormal and more strongly associated with disease, whereas the significance of many other detected types in diarrheic feces remains less clear. In this study, the C. perfringens isolates were cpa-only, not type C, which makes the findings more useful as surveillance data than as evidence of a direct disease signal. (aaep.org)

Other published work underscores why that distinction matters. A 2021 UC Davis case series on foals with diarrhea found fecal PCR evidence of C. perfringens and/or C. difficile toxin genes in 57% of 28 cases, but it framed those results within active clinical disease and hospital presentation. Separately, a study of neonatal foals and mares at a referral hospital found C. difficile could be isolated commonly and transiently, including in the absence of identifiable disease clusters, highlighting how easily detection can outpace interpretation. Taken together, those reports support the Turkish authors’ argument that more complete clinical phenotyping and toxin testing are needed before prevalence data can be translated into case definitions or treatment decisions. (journals.sagepub.com)

Why it matters: For veterinarians, diagnostic labs, and breeding operations, the paper is useful less for what it proves than for what it helps frame. It provides a regional baseline in a country where published foal data have been limited, and it reinforces a practical message: positive clostridial PCR or culture results should be interpreted alongside age, clinical signs, farm history, and toxin testing. That’s especially relevant in foals, where diarrhea differentials remain broad and can include rotavirus, Salmonella, Lawsonia intracellularis, parasites, and other infectious or management-related causes. Overinterpreting a positive molecular result could push clinicians toward unnecessary antimicrobial use or distract from infection control and supportive care priorities. (mdpi.com)

The study also has some surveillance value for herd and farm-level planning. Because both bacterial targets were found across all five provinces, the findings suggest these organisms, or at least their genetic signatures, are geographically distributed rather than isolated to one local production system. For stud farms and referral practices, that supports continued attention to fecal sample handling, isolation protocols for diarrheic foals, and careful interpretation of lab panels that detect toxin genes faster than they can establish disease causality. AAEP guidance notes that proper sample handling matters, and that clostridial spores can persist in the environment, raising the stakes for biosecurity in breeding and hospital settings. (mdpi.com)

What to watch: The most useful follow-on work would be prospective studies in Turkish foals that collect standardized clinical data, compare healthy and diarrheic animals, culture C. difficile directly, quantify organism burden, and test for toxins rather than gene targets alone. If those studies can connect molecular detection with clinical outcomes, they’d move the field from descriptive surveillance toward more actionable diagnostic thresholds. (mdpi.com)