Summer Pasture-Associated Recurrent Airway Obstruction
(SPA-RAO)
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This article is still under construction. |
Also known as: Summer Pasture-Associated Obstructive Pulmonary Disease, Summer Pasture-Associated Heaves
Description
Summer Pasture-Associated Recurrent Airway Obstruction(SPA-RAO) is a disease affecting horses kept at pasture (in contrast to Recurrent Airway Obstruction that affects horses that are stabled and fed hay). The disease is characterised by airway inflammation, increased airway mucus production and bronchoconstriction.
Signalment
The average age of onset of SPA-RAO is 9 years of age. There is no sex or breed disposition reported.
Pathogenesis
The pathogenesis of the disease is largely unknown but it suggested hypotheses include inhaled pollens or outdoor moulds and ingestion of a pasture-derived pneumotoxin.
Clinical signs
Clinical signs are similar to those associated with RAO but occur in horses kept out at pasture during the summer months. Signs may include exercise intolerance, cough (often productive), dyspnoea, increased expiratory effort and flared nostrils. Pyrexia is not usually a feature of SPA-RAO. An abdominal 'heave' line may be visible due to hypertrophy of the external abdominal oblique muscles. Lung field auscultation reveals fine crackles and wheezes or significantly reduced lung sounds in severe cases of SPA-RAO.
References
- McGorum, B. C., Edward Robinson, N., Dixon, P. M., Schumacher, J. (2007) Equine respiratory medicine and surgery Elsevier Health Sciences