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==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 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.

SPA-RAO generally affects adult horses only and the average age of onset is 9 years of age. There is no reported sex predilection but Quarter Horses and Appaloosas are more prone to developing the condition.

==Clinical signs==

==Clinical signs==

Clinical signs are similar to those associated with RAO but occur in horses kept out at pasture during the summer months, usually for more than twelve hours a day. Signs may include exercise intolerance, cough (often productive), dyspnoea, increased expiratory effort, nasal discharge and flared nostrils. Pyrexia may be a feature if a seconday bacterial infection has occurred in the airways. In severe cases, affected horses stand with their neck arched and elbows abducted. An abdominal 'heave' line may also be visible due to hypertrophy of the external abdominal oblique muscles. Lung field auscultation reveals fine crackles and wheezes. In severe cases, wheezes may be audible without a stethoscope.  

Clinical signs are similar to those associated with RAO but occur in horses kept out at pasture during the summer months, usually for more than twelve hours a day. Signs may include exercise intolerance, productive cough, dyspnoea, increased expiratory effort, nasal discharge and flared nostrils. Lung field auscultation reveals fine crackles and wheezes. In severe cases, wheezes may be audible without a stethoscope. Pyrexia may be a feature if a secondary bacterial infection of the airways has occurred. In severe cases, affected horses stand with their neck arched and elbows abducted. An abdominal 'heave' line may also be visible due to hypertrophy of the external abdominal oblique muscles.  

==Diagnosis==

==Diagnosis==

==Treatment and management==

==Treatment and management==

Control of environmental exposure is essential in horses affected by SPA-RAO. Affected horses should only be allowed access to pasture during late autumn, winter and early spring. They should ideally be kept stabled in a dust-free environment such as a stable with rubber matting and no bedding. If hay appears to act as a trigger to the horse, a complete pelleted diet may be fed or alternatively hay should be soaked. Alfalfa has been previously associated with less respiratory problems than grass hay and may be preferable.

Control of environmental exposure is essential in horses affected by SPA-RAO. Affected horses should only be allowed access to pasture during late autumn, winter and early spring. They should ideally be kept stabled in a dust-free environment such as a stable with rubber matting and no bedding. If hay appears to act as a trigger to the horse, a complete pelleted diet may be fed or alternatively hay should be thoroughly soaked. Alfalfa hay has been previously associated with less respiratory problems than grass hay and may be a preferable source of roughage for affected horses.

In some cases, the response to environmental management may be significant and drug treatment may not be required. In more severe cases, drug therapy may be required to suffiently manage the horse's condition. Corticosteroids may be administered via nebuslisation using an inhaler in order to allow the maximum concentration of the drug in the respiratory tract, with minimal systemic side effects. This can be combined with a bronchodilator such as clenbuterol. Antibiotics may be required if seconday bacterial infection is present.

In some cases, the response to environmental management may be significant and drug treatment may not be required. In more severe cases, drug therapy may be required to suffiently manage the horse's condition. Corticosteroids may be administered via nebuslisation using an inhaler in order to allow the maximum concentration of the drug in the respiratory tract, with minimal systemic side effects. This can be combined with a bronchodilator such as clenbuterol. Antibiotics may be required if seconday bacterial infection is present.

   

   

==References==

==References==

*McGorum, B. C., Edward Robinson, N., Dixon, P. M., Schumacher, J. (2007) '''Equine respiratory medicine and surgery''' ''Elsevier Health Sciences''   

*McGorum, B. C., Edward Robinson, N., Dixon, P. M., Schumacher, J. (2007) '''Equine respiratory medicine and surgery''' ''Elsevier Health Sciences''   

*Orsini, J. A., Divers, T. (2007) '''Equine Emergencies: Treatment and Procedures''' ''Elsevier Health Sciences''

*Orsini, J. A., Divers, T. (2007) '''Equine Emergencies: Treatment and Procedures''' ''Elsevier Health Sciences''

[[Category:Allergic Respiratory Diseases]][[Category:Horse]][[Category:To Do - Blood]][[Category:To Do - SophieIgnarski]]

[[Category:Allergic Respiratory Diseases]][[Category:Horse]][[Category:To Do - Blood]][[Category:To Do - SophieIgnarski]]