This refers to diseases of the lung that are inflammatory in nature. Horses with this condition typically exhibit an increased respiratory rate and effort. A cough or nasal discharge may also be observed. Inflammatory conditions typically do not elicit a fever, so the presence of a fever is a reliable way to distinguish between a condition that is infectious as opposed to inflammatory. An individual may have an inflammatory disease without an infectious component, however most infectious diseases are usually accompanied by an inflammatory component.
Heaves, formerly referred to as COPD, is the most common inflammatory disease that affects the lower respiratory tract of horses. It is precipitated by exposure to dusts and allergens in the horse's environment, which in turn cause inflammation of the lower or small airways. Inflammation may then lead to mucus production and/or constriction of the small airways leading to respiratory compromise. Of the many respiratory ailments that horses present to the Mid Atlantic Equine Medical Center for evaluation of, heaves is the most frequently diagnosed disorder.