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| Environmental control to reduce allergen exposure is key to the management of recurrent airway obstruction, as signs will re-appear following discontinuation of medication if this is not implemented. Since dusts in hay and straw are the most common triggers for disease, animals should be kept at pasture if possible. The availability of fresh grass eliminated the need for hay, and supplementary feeding can be achieved with pelleted feedstuffs. Round bale hay should not be provided as it is particularly allergenic and can cause environmental control to fail<sup>merck</sup>. If turn-out is not possibly, for example due to weather conditions, stalled horses should be maintained in a clean, controlled environment. Complete feeds may be fed that totally eliminate the need for roughge, although some horses prefer hay cubes or hay silage, which are equally acceptable. Soaked hay should not be fed as dust is incompletely removed and the nutritional content is poor. Shavings, newspaper or peat rather than straw should be used to bed animals, and supplies of hay and straw should not be kept in the same building as a RAO-afflicted animal. The addition of good ventilation to the stable design is also helpful if feasible. For example, a louvered vent may be added at the back of the stable, and the top door kept permanently open. Some horses will be controlled by environmental management alone. | | Environmental control to reduce allergen exposure is key to the management of recurrent airway obstruction, as signs will re-appear following discontinuation of medication if this is not implemented. Since dusts in hay and straw are the most common triggers for disease, animals should be kept at pasture if possible. The availability of fresh grass eliminated the need for hay, and supplementary feeding can be achieved with pelleted feedstuffs. Round bale hay should not be provided as it is particularly allergenic and can cause environmental control to fail<sup>merck</sup>. If turn-out is not possibly, for example due to weather conditions, stalled horses should be maintained in a clean, controlled environment. Complete feeds may be fed that totally eliminate the need for roughge, although some horses prefer hay cubes or hay silage, which are equally acceptable. Soaked hay should not be fed as dust is incompletely removed and the nutritional content is poor. Shavings, newspaper or peat rather than straw should be used to bed animals, and supplies of hay and straw should not be kept in the same building as a RAO-afflicted animal. The addition of good ventilation to the stable design is also helpful if feasible. For example, a louvered vent may be added at the back of the stable, and the top door kept permanently open. Some horses will be controlled by environmental management alone. |
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− | When medical therapy is neccessary, bronchodilators and corticosteroids are used. Bronchodilators, such as clenbuterol, are used to relieve bronchospasm in an attempt to minimise respiratory distress. Since mucus accumulation and inflammatory changes in the airway wall contribute to obstruction as well as bronchospasm, complete resolution may not be seen<sup>allen</sup>. Atropine is the best "rescue drug" in the event of severe respiratory disress. | + | When medical therapy is neccessary, bronchodilators and corticosteroids are used. Bronchodilators, such as clenbuterol, are used to relieve bronchospasm in an attempt to minimise respiratory distress. Since mucus accumulation and inflammatory changes in the airway wall contribute to obstruction as well as bronchospasm, complete resolution may not be seen<sup>allen</sup>. Atropine is the best "rescue drug" in the event of severe respiratory disress. The concurrent administration of corticosteroids with bronchodilators address airway inflammation as well as bronchospasm. Oral, intravenous of inhaled steroids may be used. Inhaled steroids are advantageous as they are delivered directly to the site of inflammation and so lower doses are required. Fewer systemic side-effects are therefore experienced. However, in RAO the airways requiring anti-inflammatory treatment are obstructed, and inhaled steroids are only of use after lung function has been improved through the used of bronchodilators or systemic corticosteroids<sup>allen</sup>. In mild to moderate cases this prior treatment may not be neccessary before the use of inhaled medication. Generally, medical treatment should be considered a short-term measure while environmental improvements are instituted. |
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− | NSAID, antihistamines, and leukotriene-receptor antagonists have failed to demonstrate therapeutic benefit. | + | NSAID, antihistamines, and leukotriene-receptor antagonists have all failed to demonstrate therapeutic benefit in RAO<sup>mercj</sup>. |
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− | Corticosteroids
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− | Many horses benefit from corticosteroid administration
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− | early in the course of the disease in conjunction with bronchodilators,
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− | as this will address the underlying inflammation
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− | as well as bronchospasm. Corticosteroids
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− | can be administered systemically
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− | using intravenous or oral
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− | preparations, or by inhalation. (The
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− | association between cortico steroids
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− | and laminitis should be discussed
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− | with the owner.)
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− | The advantage of inhaled corticosteroids
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− | is that they are administered
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− | directly to the respiratory
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− | tract; therefore, the required therapeutic
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− | dose is lower, resulting
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− | in less systemic absorption and
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− | hence less risk of side effects. The
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− | pulmonary distribution of inhaled
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− | cortico steroids is poor during
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− | severe airway obstruction, so this
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− | method of administration should
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− | only be used after an improvement
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− | in lung function has been
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− | achieved with systemic corticosteroids
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− | and/or bronchodilators.
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− | In mild to moderate cases, systemic corticosteroids may
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− | not be required and inhaled corticosteroids may be used
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− | from the outset. Ideally, inhaled corticosteroids should
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− | be administered after inhaled bronchodilators to improve
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− | their penetration to the lower airways.
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− | In the majority of cases, medical treatment should be
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− | considered a short-term measure while environmental
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− | improvements are instituted.
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