Impact of Lower Airway Inflammation on Fitness Parameters in Standardbred Racehorses.
Authors: Lo Feudo Chiara Maria, Stucchi Luca, Conturba Bianca, Stancari Giovanni, Ferrucci Francesco
Journal: Animals : an open access journal from MDPI
Summary
Lower airway inflammation in Standardbred racehorses, particularly mild-moderate equine asthma (MEA), is widely accepted to compromise performance, yet the specific mechanisms linking airway pathology to fitness decline remain poorly characterised. Researchers retrospectively analysed diagnostic records from 116 Standardbreds presenting with poor performance, correlating endoscopic findings and bronchoalveolar lavage (BAL) cytology with fitness parameters obtained from incremental treadmill testing. Elevated neutrophil percentages in BAL fluid showed inverse relationships with key performance markers—specifically speed at 200 bpm heart rate, speed and heart rate at 4 mmol/L plasma lactate (VLa4 and HRLa4), and maximal speed—whilst correlating positively with elevated resting lactate concentrations. Notably, horses were stratified into neutrophilic, eosinophilic-mastocytic, and mixed inflammation subtypes, with significant performance differences identified between groups, particularly for VLa4, HRLa4, and lactate kinetics. For practitioners managing racehorses with suspected respiratory disease, these findings underscore that neutrophilic lower airway inflammation represents a quantifiable impediment to aerobic capacity and metabolic efficiency, suggesting that BAL cytology should inform performance expectations and treatment urgency in clinical decision-making.
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Practical Takeaways
- •Standardbreds presenting with poor race performance should be evaluated for lower airway inflammation via BAL cytology, as neutrophilic inflammation directly impairs fitness parameters and lactate clearance
- •Different MEA subtypes (neutrophilic vs. eosinophilic-mastocytic) show distinct effects on performance metrics; treatment protocols may need to be tailored based on BAL cell populations
- •Fitness testing (incremental treadmill test with lactate and heart rate monitoring) can help identify airway inflammation-related performance limitations in racehorses
Key Findings
- •Neutrophil percentages in BAL fluid were inversely correlated with speed at heart rate 200 bpm, VLa4, HRLa4, and maximal speed in Standardbred racehorses
- •Neutrophilic airway inflammation was positively correlated with higher plasma lactate concentrations during exercise testing
- •Significant differences in VLa4, HRLa4, and lactate concentrations were detected between neutrophilic, eosinophilic-mastocytic, and mixed MEA subtypes
- •Airway neutrophilic inflammation impairs athletic capacity and fitness parameters in Standardbred racehorses