Field-applicable low-intensity exercise induces bronchodilation in horses with severe asthma

Area of Science:

• Equine respiratory medicine
• Veterinary pulmonology
• Animal exercise physiology

Background:

• Severe equine asthma (SEA) causes significant airway dysfunction, leading to poor outcomes for affected horses.
• While intense exercise induces bronchodilation in SEA, the effects of lighter, field-applicable training are less understood.

Purpose of the Study:

• To assess the impact of submaximal aerobic exercise on airway obstruction in horses experiencing SEA exacerbation.
• To compare exercise-induced bronchodilation with the effects of a standard bronchodilator medication.

Main Methods:

• A preliminary study evaluated a 25-minute standardized exercise regimen on lung function in eight SEA horses.
• A randomized controlled crossover trial compared lung function changes after standardized exercise versus turnout.
• Lung mechanics were measured pre- and post-intervention; salbutamol was administered post-turnout for comparison.

Main Results:

• Standardized exercise significantly reduced pulmonary resistance by approximately 50% in SEA horses.
• Pulmonary resistance decreased from 2.6 to 1.3 cm H2O/L/s post-exercise (p=0.006), while remaining unchanged after turnout.
• Exercise-induced bronchodilation was comparable in magnitude to that achieved with the bronchodilator salbutamol.

Conclusions:

• Brief aerobic exercise induces rapid and potent bronchodilation in horses with SEA.
• These findings suggest that exercise programs warrant further investigation for managing SEA.
• Limitations include a small sample size, lack of blinding, and focus on short-term effects.