Topography of the respiratory, oral, and guttural pouch bacterial and fungal microbiotas in horses.
Authors: Bond Stephanie, McMullen Christopher, Timsit Edouard, Léguillette Renaud
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Respiratory Tract Microbiotas in Healthy Horses Understanding the baseline microbial composition of the equine respiratory tract is essential for interpreting changes associated with disease, yet detailed characterisation of bacterial and fungal communities across anatomical sites had been lacking until this 2023 study. Researchers sampled eleven anatomical locations—from the nostrils through to the guttural pouches—in eleven healthy Thoroughbreds using swabs, protected specimen brushes, and saline washes, then sequenced the 16S rRNA gene (V4) and ITS2 region to profile both bacterial and fungal communities. The nasopharynx emerged as a critical hub: its microbial composition most closely resembled that of the distal trachea in healthy horses, suggesting it functions as the primary reservoir supplying microorganisms to the lower respiratory tract, whilst fungal diversity was notably highest in the nostrils and decreased progressively distally. The study revealed greater spatial heterogeneity in bacterial communities than fungal ones, with community richness declining at more distal sampling locations. For practitioners, these findings highlight the nasopharynx as a strategically important sampling site for respiratory microbiota investigations, and suggest that nasopharyngeal swabs may prove valuable in future studies seeking to identify reliable disease biomarkers—potentially offering a non-invasive alternative to lower airway sampling in clinical assessment of respiratory conditions.
Read the full abstract on PubMed
Practical Takeaways
- •Nasopharyngeal swabs may be a practical and non-invasive sampling method for monitoring lower respiratory tract microbiota in clinical practice, pending validation of disease biomarkers
- •Understanding normal respiratory microbiota topography provides a baseline for identifying pathological changes associated with respiratory disease in horses
- •The pharynx appears to be a critical gateway for microbial colonization of the lower respiratory tract and warrants targeted investigation in respiratory disease studies
Key Findings
- •Fungal species richness and diversity were highest in the nostrils, with decreasing diversity at more distal respiratory locations
- •Bacterial composition showed greater spatial heterogeneity across sampling locations compared to fungal communities
- •Pharyngeal microbiota composition was most similar to distal tracheal microbiota, suggesting the pharynx as the primary source of bacteria and fungi to the lower respiratory tract
- •Eleven distinct anatomical locations along the respiratory tract harbour different microbial niches in healthy horses