Horse Respiratory Disease and Indoor Air Quality

Respiratory disease is one of the most common health problems in stabled horses. The air quality in traditional horse stabling is often dramatically worse than required for good lung health.

Key Facts

Equine asthma (inflammatory airway disease and severe equine asthma) affects approximately 14% of horses, with higher rates in stabled animals
Dust from hay, bedding, and arena surfaces is the primary trigger — even hay that appears dust-free can release millions of spores when shaken
Horses breathe 60-100 liters of air per minute at rest — poor stable ventilation rapidly concentrates airborne particles and ammonia
Soaking hay for 30-60 minutes or using haylage dramatically reduces respirable dust compared to dry hay
Good stable ventilation requires air flow without drafts — ridge ventilation and low-level inlets are more effective than open top doors alone
Horses with respiratory disease show reduced exercise tolerance, chronic cough, and nasal discharge — often misattributed to poor fitness

Welfare Considerations

Poor indoor air quality is a pervasive welfare problem for stabled horses that causes or exacerbates respiratory disease in a substantial proportion of the population. The condition is progressive — years of exposure to dusty hay and poor ventilation causes irreversible airway remodeling. Many horses perform significantly below their potential because of undiagnosed or poorly managed respiratory disease. The welfare and performance costs of poor air quality are high, yet the interventions are straightforward: wet forage, appropriate bedding, and ventilation. Making these changes is one of the highest-impact welfare improvements available for stabled horses.

What You Can Do

Switch to haylage, steamed hay, or thoroughly soaked hay for horses with or at risk of respiratory disease
Maximize stable ventilation without creating drafts at horse height
Use low-dust bedding (shavings, paper, rubber matting) rather than straw where respiratory disease is a concern
Have any horse with chronic cough assessed by a vet — do not assume it is normal
Consider turning out affected horses more rather than stabling them in poor air quality environments