Equine asthma (formerly heaves or RAO) is a common chronic respiratory condition causing breathing difficulty and reduced quality of life. Management significantly improves welfare and often restores performance.
Equine asthma causes chronic respiratory distress that significantly impairs quality of life. Horses with severe asthma strain visibly to breathe, develop abdominal muscle hypertrophy (the heave line) from chronic respiratory effort, and are unable to perform any meaningful exercise without respiratory compromise. The condition causes suffering analogous to severe human asthma — each breath requiring effort rather than occurring effortlessly. Environmental management is welfare-transformative: horses moved from dusty hay and straw environments to turnout with haylage or steamed hay show dramatic clinical improvement. The welfare and management message is clear: dust is the enemy, and its elimination is achievable in almost every management context.