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. 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 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.

==Signalment==

==Signalment==

The average age of onset of SPA-RAO is 9 years of age. There is no reported sex predilection but Quarter Horses are over-represented.

The average age of onset of SPA-RAO is 9 years of age. There is no reported sex predilection but Quarter Horses are over-represented.

==Clinical signs==

==Clinical signs==