Cytological Findings in Bronchoalveolar Lavage Fluid of Foals With Pneumonia Caused by Rhodococcus equi and Other Bacteria.
Authors: Vitale Valentina, Sgorbini Micaela, Cuteri Vincenzo, Preziuso Silvia, Attili Anna Rita, Bonelli Francesca
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Distinguishing Rhodococcus equi pneumonia from other bacterial respiratory infections in foals remains clinically challenging, particularly when culture results are pending. This retrospective analysis examined bronchoalveolar lavage fluid (BALF) cytology from 19 foals (aged 3 weeks to 6 months) with lower respiratory tract infections, comparing eight cases of confirmed R. equi pneumonia against eleven cases of other bacterial pneumonias. Foals with R. equi infection demonstrated significantly elevated total nucleated cell counts and neutrophil percentages (P = .02 and P = .002 respectively), whilst macrophage proportions were notably reduced compared to those with alternative bacterial aetiologies (P = .01). These cytological differences offer practical value for field practitioners: BALF analysis—a minimally invasive procedure requiring only basic equipment—can help differentiate R. equi bronchopneumonia from competing diagnoses before culture confirmation becomes available, potentially guiding earlier therapeutic decisions. For farriers and coaches working alongside veterinary teams, recognising that elevated neutrophilia with suppressed macrophage presence in BALF may indicate R. equi rather than commensal or environmental pathogens emphasises the importance of prompt veterinary investigation in young foals presenting with respiratory signs, given the disease's characteristic severity and specific management requirements.
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Practical Takeaways
- •BALF cytology showing elevated neutrophils with reduced macrophages suggests R. equi pneumonia in young foals with respiratory disease, allowing earlier targeted treatment decisions before culture confirmation
- •Bronchoalveolar lavage is a practical field procedure requiring minimal equipment that can help differentiate R. equi from other bacterial causes of foal pneumonia
- •Consider R. equi as a likely diagnosis in foals aged 3 weeks to 6 months presenting with pneumonia and elevated neutrophil/reduced macrophage proportions on BALF analysis
Key Findings
- •R. equi-positive foals had statistically significant higher total nucleated cell count (P = 0.02) and neutrophil percentage (P = 0.002) compared to R. equi-negative foals
- •Macrophage proportion was significantly lower in R. equi-positive foals than R. equi-negative foals (P = 0.01)
- •8 of 19 foals (42.1%) had R. equi pneumonia while 11 of 19 (57.9%) had other bacterial pneumonias
- •Bronchoalveolar lavage fluid cytological analysis can differentiate R. equi pneumonia from other bacterial pneumonias while awaiting culture results