Ocular Microbiome in a Group of Clinically Healthy Horses.
Authors: Santibáñez Rodrigo, Lara Felipe, Barros Teresa M, Mardones Elizabeth, Cuadra Françoise, Thomson Pamela
Journal: Animals : an open access journal from MDPI
Summary
# Ocular Microbiome in Clinically Healthy Horses Until recently, our understanding of the bacterial communities inhabiting the equine eye has relied heavily on conventional culture-based methods, which substantially underestimate microbial diversity and function. Using next-generation sequencing of conjunctival swabs from 14 healthy horses, Santibáñez Rodrigo and colleagues identified a far more complex ocular microbiome than previously documented, dominated by Pseudomonadota (59.88%), Actinomycetota (22.44%), and Bacteroidota (16.39%), with 278 distinct genera detected including Massilia, Pedobacter, Pseudomonas, and Sphingomonas as prevalent residents. Functional analysis revealed these microbial communities are primarily engaged in fundamental metabolic processes—aerobic respiration, amino acid synthesis, and lipid biosynthesis—suggesting they play established rather than pathogenic roles in the healthy ocular environment. The considerable heterogeneity observed between individual horses, particularly among Actinobacteria and Bacteroidetes, indicates that the equine ocular microbiome operates as a distinct ecosystem shaped by individual variation rather than a uniform bacterial signature. These findings provide equine practitioners with a new baseline for understanding normal ocular health and may help contextualise inflammatory or infectious eye conditions by revealing when microbial shifts represent genuine dysbiosis rather than normal variation.
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Practical Takeaways
- •Understanding the normal equine ocular microbiome composition provides a baseline for identifying pathogenic shifts in horses with eye disease
- •The dominance of Proteobacteria in healthy eyes suggests this phylum represents a normal colonizer rather than an inherent pathogen in equine ocular surfaces
- •Future diagnostic protocols for equine ocular infections should reference this healthy microbiome profile to distinguish commensals from disease-causing organisms
Key Findings
- •Pseudomonadota (Proteobacteria) comprised 59.88% of ocular microbiota, followed by Actinomycetota (22.44%) and Bacteroidota (16.39%), totaling 98.72% of communities
- •Six genera (Massilia, Pedobacter, Pseudomonas, Sphingomonas, Suttonella, Verticia) were present in >5% of samples analyzed
- •Inferred metabolic pathways were dominated by aerobic respiration, amino acid biosynthesis, and lipid biosynthesis
- •Actinobacteria and Bacteroides showed high heterogeneity between individual samples