Respiratory diseases and their effects on respiratory function and exercise capacity.
Authors: Van Erck-Westergren E, Franklin S H, Bayly W M
Journal: Equine veterinary journal
Summary
# Editorial Summary Since aerobic metabolism underpins athletic performance across most equestrian disciplines, even mild respiratory disease can significantly compromise exercise capacity by increasing breathing impedance and reducing effective ventilation. Van Erck-Westergren and colleagues reviewed how respiratory pathology—whether affecting upper airways, lower airways, or both—impairs respiratory mechanics and arterial blood gas exchange, with the severity of functional deficit varying according to disease stage and the specific demands of the sport. A key finding is that many airway conditions remain subclinical at rest, becoming apparent only under the stress of exercise; consequently, diagnosis often requires dynamic assessment rather than resting examination alone, with exercise testing designed specifically to reproduce the clinical problem and reveal arterial lactate and blood gas abnormalities. The authors emphasise that airway sampling techniques can identify subclinical lower airway inflammation capable of reducing performance even when horses appear healthy in the stable. For practitioners involved in athletic horse management, this work underscores the value of sport-specific diagnostic protocols—particularly ridden or treadmill exercise testing combined with airway cytology—to distinguish true respiratory limitation from other causes of poor performance and to objectively monitor treatment efficacy and long-term management strategies.
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Practical Takeaways
- •Even mild respiratory diseases can significantly impair athletic performance in horses; routine respiratory assessment should be part of pre-purchase and performance evaluations
- •Many respiratory problems are subclinical at rest and only manifest during exercise, so diagnostic exercise testing is essential for horses with suspected performance issues
- •Combine multiple diagnostic techniques (exercise testing, airway sampling, blood gas analysis) to identify subclinical lower airway disease and monitor treatment effectiveness in athletic horses
Key Findings
- •The respiratory system can be a rate-limiting factor in exercise capacity of fit and healthy horses due to reliance on aerobic metabolism
- •Respiratory diseases result in increased respiratory impedance, increased work of breathing, and reduced ventilation detectable through changes in breathing mechanics and arterial blood gas tensions
- •Airway diseases have high prevalence in equine athletes and may be subclinical at rest but become clinically relevant only during exercise
- •Exercise testing is critical for diagnosing subclinical respiratory conditions and establishing accurate diagnosis when clinical signs are exercise-induced