TERMINOLOGY OF SMALL AIRWAY DISEASE

Large airways:

• The nasal passages, throat, trachea (windpipe), and major bronchi.

Small Airways:

• Small bronchi and bronchioles.

Terms Used for Small Airway Diseases:

• SAD = Small Airway Disease (large category including any non-infectious disease of the small airways).
• SAID = Small Airway Inflammatory Disease (inflammation of the small bronchi and bronchioles).
• IAD = Inflammatory Airway Disease (same as SAID, except includes small and large airways).
• COPD = Chronic Obstructive Pulmonary Disease (Heaves). These horses have had recurrent bouts of severe airway inflammation resulting in permanent thickening of the airway walls. With repeated exposure to allergen, or on hot humid days, horses with COPD have difficulty breathing.
• Heaves = recurrent episodes of airway obstruction, which result in forceful breathing, coughing, wheezing, and low blood oxygen tensions.  In some horses with heaves, the damage is permanent, while in others the disease can be controlled with environmental management and maintenance treatments.
• Recurrent airway obstruction = Heaves.
• Reactive airway syndrome = any horse with hyper-reactive airways. Clinically, these horses are usually presented to the veterinarian for recurrent cough.
• Chronic bronchitis / bronchiolitis = inflammation of the small airways as confirmed by biopsy.