Bronchoalveolar lavage fluid from both lungs in horses: Diagnostic reliability of cytology from pooled samples.

The research study investigates if pooling bronchoalveolar lavage fluid (BALF) samples from both lungs of a horse can accurately represent individual lung samples in diagnosing conditions such as mild or severe equine asthma and exercise-induced pulmonary haemorrhage. The results suggest that a pooled BALF sample is, indeed, representative of individual lung samples, making it a reliable method for diagnosing these conditions.

Methodology

• Fifty-one horses with poor performance and/or respiratory symptoms were included in this study.
• BALF was collected from both lungs of each horse.
• The study compared cytology of pooled BALF samples to that of individual BALF samples.
• Horses were categorized based on clinical signs and individual BALF cytologies into four groups: control (CTL), mild equine asthma (mEA), severe equine asthma (sEA), and/or exercise-induced pulmonary haemorrhage (EIPH).
• An undisclosed (masked) protocol was used to conduct cytology on pooled and individual BALF samples.

Findings

• No significant difference was found between pooled and individual BALF samples for all cell types.
• Strong correlations were observed between pooled and individual samples for neutrophil proportions and haemosiderophages/macrophages ratio, while moderate correlations were observed for metachromatic cell and eosinophil proportions.
• Using threshold values determined by receiver operating characteristic (ROC) analysis, good categorical agreements were found for diagnosing mEA/sEA, and substantial agreements for diagnosing EIPH.
• Using a pooled BALF sample, only one horse was wrongly classified as CTL instead of mEA, and three horses were classified as EIPH instead of CTL.

Conclusion

• The study concludes that cytology of a pooled BALF sample is representative of individual lung samples. Therefore, this approach can be utilized as a valid method for diagnosing equine asthma in horses.