Does your horse cough during exercise or at rest? Is your horses breathing worse when stabled or during the summer months? 

Your horse could be suffering from a disease called recurrent airway obstruction. A few presentations of the disease exist and will be discussed.




Classical recurrent airway obstruction (RAO)


An allergic response to mould spores, typically found in hay and straw. The spores are breathed in and result in inflammation, increased mucus production and constriction of the lower airways.


Clinical signs may initially be mild such as coughing occasionally during exercise, but as the severity of the condition progresses, coughing will become more frequent and also occur at rest. Respiratory rate (breaths per minute) and effort will increase. Sometimes horses will present in respiratory distress. Signs of this include; high respiratory rate (greater than20 breaths per minute), flared nostrils, wheezing and abdominal effort when breathing at rest.


Diagnosis is often made based on clinical signs and response to treatment. Sometimes a sample will be taken from the lungs to confirm RAO and rule out other causes.


Treatment  predominantly involves careful management; soak hay for at least 20mins, ensure it is fully immersed in water and change water regularly. Alternatively haylage can be fed or hay steamed using the Haygain system. Turn the horse out at pasture 24hours a day. If this is not an option then keep the horse and all other in-contact horses in the barn on a dust free bed. It is prudent to remove the affected horse from the stable when mucking out and make sure the  ventilation is optimal. Medical intervention may be necessary in some cases;  Clenbuterol (ventipulmin or dilaterol), is a drug which dilates the airways, making breathing easier. In some cases inhaled steroids will be necessary to combat the inflammatory process.


Studies have shown that only a few minutes of exposure to allergens can result in days of coughing so management changes must be adhered  to at all times.

Summer pasture associated recurrent airway obstruction (SPARAO)

This disease involves an allergic response to pollens in the environment. Affected horses will be worse when pollen counts are high and they are out in the field.


Clinical signs are the same as RAO but time of year and current management regime dictate as to whether a diagnosis of SPARAO is more likely.


Treatment. The horse should be stabled during the summer but the same changes to stable management should be made as for a horse suffering from RAO. Inhaled corticosteroids are usually required to keep the lungs settled.