Presence and distribution of yeasts in the reproductive tract in healthy female horses.
Authors: Azarvandi A, Khosravi A R, Shokri H, Talebkhan Garoussi M, Gharahgouzlou F, Vahedi G, Sharifzadeh A
Journal: Equine veterinary journal
Summary
# Editorial Summary Yeasts represent a normal component of the equine reproductive microbiota, yet their specific composition and distribution within the caudal tract remain poorly characterised. Azarvandi and colleagues cultured samples from the vestibule, clitoral fossa and vagina of 151 clinically healthy mares using standardised mycological techniques, identifying yeast colonies in approximately 40% of animals across nine distinct genera. Candida species predominated, accounting for over half of all isolates, with *Candida krusei* being significantly more prevalent than other Candida spp., whilst notable secondary colonisers included *Cryptococcus*, *Saccharomyces* and *Geotrichum*. Anatomically, the vestibule yielded substantially more isolates than the vagina (48.0% versus 18.3%), and multiparous mares demonstrated significantly higher isolation rates than maiden mares—a finding that may reflect tract changes associated with parity. For practitioners initiating empirical antimicrobial therapy in cases of reproductive tract disease before culture results are available, recognition of these commensal yeasts is clinically relevant; interpreting positive yeast cultures requires careful correlation with clinical signs and cytological findings rather than reflexive treatment, particularly when *C. krusei* is identified in asymptomatic animals.
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Practical Takeaways
- •Candida spp., particularly C. krusei, are normal flora in healthy mares' reproductive tracts and should not automatically be treated as pathogens without clinical signs
- •Location matters: sample from the vestibule rather than vagina for higher diagnostic yield if yeast identification is clinically indicated
- •Multiparous mares have higher yeast colonization rates, which may inform decision-making around empirical treatment protocols in breeding contexts
Key Findings
- •Yeast colonies were isolated from 60 horses (39.7%), belonging to nine genera with Candida spp. representing 53.2% of isolates
- •Candida krusei was the most frequent Candida species isolated at 43.1%, with significantly higher prevalence than other Candida species (P<0.05)
- •The vestibule contained significantly more yeast isolates (48.0%) compared to the vagina (18.3%)
- •Multiparous females had significantly higher yeast isolation rates (76.8%) compared to maiden mares (P<0.05)