Changes

==Description==

==Description==

Summer Pasture-Associated Recurrent Airway Obstruction (SPA-RAO) is an inflammatory condition of the lower airways affecting pasture-kept horses. This is in contrast to Recurrent Airway Obstruction that affects horses that are stabled. The disease is characterised by airway inflammation, increased airway mucus production, reduced mucociliary clearance and bronchoconstriction in response to allergen exposure. The pathogenesis of the disease is largely unknown but suggested hypotheses include inhaled pollens or outdoor moulds or ingestion of a pasture-derived pneumotoxin. It occurs most commonly in the South of the United States but has also been reported in the United Kingdom.

Summer Pasture-Associated Recurrent Airway Obstruction (SPA-RAO) is an inflammatory condition of the lower airways affecting pasture-kept horses. This is in contrast to Recurrent Airway Obstruction that affects horses that are kept in a stabled environment. The disease is characterised by airway inflammation, increased airway mucus production, reduced mucociliary clearance and bronchoconstriction in response to allergen exposure. The pathogenesis of the disease is largely unknown but suggested hypotheses include inhaled pollens or outdoor moulds, or ingestion of a pasture-derived pneumotoxin. It occurs most commonly in the southern states of America but has also been reported in the United Kingdom.

==Signalment==

==Signalment==

==Diagnosis==

==Diagnosis==

Diagnosis is usually based on the characteristic and seasonal appearance of clinical signs combined with a history of exposure to pasture during late spring or summer. Endoscopy may be used in order to examine the airways for the presence of inflammation or mucus. A sample of mucus may be obtained via bronchioalveolar lavage which often yields copious mucupurulent material. Cytology usually reveals >25% non-degenerate neutrophils confirming the presence of lower airway inflammation. Curschmann's spirals may also be observed, representing inspissated mucus in the obstructed lower airways.  

Diagnosis is usually based on the characteristic and seasonal appearance of clinical signs combined with a history of exposure to pasture during late spring or summer. Endoscopy may be used in order to examine the airways for the presence of inflammation or mucus. A sample of mucus may be obtained via bronchioalveolar lavage which often yields copious mucupurulent material. Cytology performed on the sample usually reveals >25% non-degenerate neutrophils confirming the presence of lower airway inflammation. Curschmann's spirals may also be observed, representing inspissated mucus in the obstructed lower airways.  

Thoracic radiology is not commonly performed but may reveal an increased bronchointerstitial pattern.

Thoracic radiology is not commonly performed but may reveal an increased bronchointerstitial pattern.