Equine Asthma is a relatively new term to the veterinary vocabulary, chosen because of the similarity to asthma in humans, and can be a difficult problem to manage. Equine Asthma covers all non-infectious respiratory disease, and now replaces terms such as RAO, IAD and COPD. Equine Asthma is a chronic disorder, which usually shows itself as a consistent cough with nasal discharge, frequently limiting the horse’s performance.
If the horse is only mildly affected then symptoms may only occur during or just after exercise, however even a mild cough should not be discounted as not a problem. Horses have a very low cough response compared to humans, therefore if a cough is seen then the horse is certainly experiencing respiratory stress. Sub-clinical respiratory stress is commonly found in working horses, and respiratory capacity is often considered to be the limiting factor for performance in elite equine athletes. Therefore maximising respiratory health should be considered for all working horses, and the as owners and trainers we ignore the occasional cough at our peril.
For those with more serious issues, they may wheeze almost constantly, with crackling being heard upon use of a stethoscope. These more severe cases may also be accompanied by heave lines, a muscular lines around the area of the ribcage, caused by muscles having to work harder in order to exhale. Normally affected horses won’t demonstrate a high temperature, though if opportunistic bacterial infections take hold, then antibiotics may be needed. For those cases where impact on performance is mild, brochoalveolar lavage may be used to assess neutrophil levels, which indicate lower respiratory tract inflammation.
A number of allergens contribute to Equine Asthma, and in summer these can drastically increase. High levels of pollen and dust exist during the warmer months and, because of this, the condition was previously known as SPARAO (Summer Pasture Associated Recurrent Airway Obstruction). Pollen is a common trigger in respiratory disorders, along with mould spores, and their ubiquitous nature can make it very difficult, if not impossible, to avoid them. These allergens cause irritation and inflammation of the delicate lining of the lungs as well as bronchoconstriction; this inflammation leads to fluid production and hence the mucus discharge and crackling chest noises.
It is recommended to adopt a low dust regime for all horses, but particularly those with signs of Equine Asthma. Choose low dust bedding and ensure well-ventilated, but not draughty, stabling. For dust sensitive individuals it is advised to increase their turnout as much as possible. However if they are particularly sensitive to pollen they may benefit from stabling at peak times, or just take care to be aware of which pollen they are sensitive to (i.e. tree, rapeseed etc), and choose a field away from these triggers if possible.
Dietary support is recommended, with research showing the benefit of antioxidant supplementation to respiratory health.
Selected References for information.
