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Chronic obstructive pulmonary disease (COPD) or recurrent airway obstruction (RAO) is one of the most common respiratory conditions in horses. The condition is caused by an allergy to fungal spores in hay, bedding and the environment and is, therefore, usually seen during the winter when horses are stabled more.
The allergic reaction to the spores causes irritation of the airways producing increased mucus secretion and thickening of the airways. |  |
Signs:
Affected horses will have a cough, increased respiratory rate (heaves) and a nasal discharge. Occasionally horses may become ill, go off their food and have an increased temperature if a secondary bacterial infection occurs in the inflamed airways.
In the early stages the damage to the lungs is reversible, however, in ongoing cases especially in older horses that have had frequent bouts of coughing the changes are permanent and the airways will remain thickened. These horses will often have a visible 'heave' line just behind the rib cage. |
Diagnosis:
Clinical signs and history of the condition are usually enough to make an initial diagnosis and start treatment, however, in many cases further tools can be used.
Endoscopy can be used to examine the presence of inflammation in the airways and amount of mucus present. A sample of this mucus can be taken, a tracheal wash, and examined to determine the cells and, in some cases, bacteria present. |
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Treatment:
The main treatment for COPD is management changes. Horses should be allowed out onto pasture as much as is possible and when they are inside stables should be well ventilated and dust free. Haylage or alfalfa pellets should be fed instead of hay to eliminate the spores being eaten. Allthough soaked hay is less dusty there are still fungal spores present. Dust free bedding such as shavings should also be used.
Drugs that can be used to manage the disease include drugs to dilate the airways (e.g. ventipulmin) and anti-inflammatory drugs (e.g. steroids). These are often best delivered directly into the lungs via an inhaler.
Antibiotics are used if bacterial infection is suspected.
In a case of acute respiratory distress similar agents can be injected to supply a more rapid response. |
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Lameness
