<i>Clostridioides difficile</i> in equidae necropsied in Northwestern France, between 2019 and 2021

<i>Clostridioides difficile,</i> an anaerobic, spore-forming enteropathogen, is less studied in animals than in humans despite its importance in One Health. We evaluated <i>C. difficile</i> occurrence, diversity, circulation, and virulence in French Equidae (<i>n</i> = 100) after their necropsy in northwestern France, from 2019 to 2021. We systematically recovered all cecal contents and any watery intestinal contents. We isolated <i>C. difficile</i> strains, determined their toxin gene profile by PCR, and established their PCR-ribotype according to the WEBRIBO database. We also performed free toxin detection. Twenty-seven Equidae were positive for <i>C. difficile</i> and 20 had a toxigenic strain, including one animal co-colonized by a non-toxigenic strain. Toxigenic isolates belonged to eight already described ribotypes: (i) 078 and 126 (toxin genes of wild-type size: <i>tcdA⁺ tcdB⁺ cdt⁺</i>), (ii) 005, 012, 020, AI-53, and FR227 (<i>tcdA⁺ tcdB⁺</i>), and (iii) 017 (<i>tcdB⁺</i>). Non-toxigenic isolates were of ribotypes 009, 035, and 439. Ribotypes 017 and 009 were predominant (<i>n</i> = 5). In two cases, Equidae of the same premises shared the same ribotype, either 020 or 009. Free toxins were detected in four animals: they displayed signs of diarrhea and a <i>C. difficile</i> of ribotype 126 (<i>n</i> = 1) or 017 (<i>n</i> = 3) as the only detected enteropathogen, suggesting a <i>C. difficile</i> infection (CDI). Three of them had received antibiotics. Two had died from an entero-toxic infection, for which <i>C. difficile</i> ribotype 017 was the only identified cause. French Equidae displayed common pathogenic <i>C. difficile,</i> and ribotype 017 was highly virulent. These findings are of concern from a One Health perspective.IMPORTANCE<i>C. difficile</i>, a major enteropathogen widely disseminated in the environment, is a One Health issue. Animals are raising concern as human contamination sources. Equidae are in close contact with humans and also develop <i>post</i>-antibiotic and healthcare-associated CDIs. The systematic survey of Equidae necropsied from 2019 to 2021 in the leading horse breeding region in France revealed that 20% harbored pathogenic strains. These belonged to clinically important ribotypes, raising the possibility of cross-species, zoonotic or anthropo-zoonotic transmission. Free toxins, which are rarely tested in animals, were detected in four animals with signs of diarrhea and a toxigenic <i>C. difficile</i> as the only identified enteropathogen, suggesting CDI. In two of them, <i>C. difficile</i> ribotype 017 was the only identified cause of entero-toxic disease and death. French Equidae could play a role in the dissemination of pathogenic <i>C. difficile</i> and notably ribotype 017. They should be surveilled carefully from a One Health perspective.