Equine COPD - or chronic obstructive pulmonary disease - is a now-obsolete term for a common condition in horses that causes coughing and poor performance. This condition is now referred to as equine asthma and is one of the most common non-infectious lung diseases. Severe equine asthma affects 14–17% of horses in some populations, but up to 70% of pleasure horses have indicators of mild to moderate asthma. Horses affected by equine asthma typically have increased mucus production, difficulty breathing during exercise and sometimes at rest, cough, and nasal discharge. More severe cases may result in acute respiratory distress.