Changes

==Description==

==Description==

[[Image:COPD.jpg|right|thumb|100px|<small><center>COPD (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]

 

[[Image:COPD scanning micrograph.jpg|right|thumb|100px|<small><center>COPD scanning electron micrograph (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]

Recurrent airway obstruction (RAO) is a common, performance-limiting, allergic respiratory disease of horses characterized by chronic cough, nasal discharge, and respiratory difficulty. Episodes of airway obstruction are observed when susceptible horses are stabled, bedded on straw, and fed hay, whereas elimination of these inciting factors results in remission or attenuation of clinical signs. The pathophysiology involves small airway inflammation (neutrophilic), mucus production, and bronchoconstriction in response to allergen exposure.

Recurrent airway obstruction (RAO) is an inflammatory, obstructive airway disease that becomes clinically evident in middle-aged horses. The disease, also known as heaves, is most prevalent in the northern hemisphere where horses are stabled for large parts of their lives and are fed hay [1]. A similar syndrome, summer pasture-associated obstructive pulmonary disease (SPAOD) occurs in the southeastern United States, Britain and California in horses that are kept on pasture when the weather is warm and humid [2,3]. Evidence to date suggests that the two syndromes are the same disease but with different initiating factors. Recurrent airway obstruction was formally known as chronic obstructive pulmonary disease (COPD). However, because of differences between equine and human COPD, a recent workshop recommended that the terms RAO or heaves, rather than COPD, be used for the horse disease [4].

Recurrent airway obstruction (RAO) is an inflammatory, obstructive airway disease that becomes clinically evident in middle-aged horses. The disease, also known as heaves, is most prevalent in the northern hemisphere where horses are stabled for large parts of their lives and are fed hay [1]. A similar syndrome, summer pasture-associated obstructive pulmonary disease (SPAOD) occurs in the southeastern United States, Britain and California in horses that are kept on pasture when the weather is warm and humid [2,3]. Evidence to date suggests that the two syndromes are the same disease but with different initiating factors. Recurrent airway obstruction was formally known as chronic obstructive pulmonary disease (COPD). However, because of differences between equine and human COPD, a recent workshop recommended that the terms RAO or heaves, rather than COPD, be used for the horse disease [4].