Recurrent Airway Obstruction

By Your Horse

25 November 2011 11:06

Recurrent airway obstruction (RAO) is a source of anxiety to many horse owners as the winter months approach and any horse can develop it. 

Here’s the best expert advice and myth-busting information to help you reduce the risk of your horse being affected this winter.


The disease

- RAO is an allergic reaction that affects the lungs – similar to the human asthma
- It usually affects stabled horses and is more common in those over nine years old
- It is an allergic reaction to an inhaled substance, or allergen
- The most common allergen are mould spores which are found in the stable environment



Signs of RAO creep up slowly and can include:
- Increased breathing rate, nasal discharge and coughing
- Loss of performance when competing
- In chronic cases, a heave line may show as the abdominal muscles have to work extra hard on expiration and wheezing can be heard
- The affected horse, if unlucky, may experience an acute attack of the respiratory distress – the horse version of a human asthma attack. Seek help as soon as possible



- A dust-free environment with as much turnout as possible
- Replace hay with haylage or vacuum-packed hay
- For mild RAO, soaked hay may be adequate – only for a good-doer
- Avoid stabling near the hay barn or muck heap
- Remove as much dust and cobwebs as possible
- Bedding needs to be as dust free as possible – rubber matting can reduce the amount of bedding required
- Make sure you vaccinate your horse every year because RAO can develop following a viral respiratory infection



- All year round turnout
- The two drugs given to RAO sufferers are:
       - Bronchodilators: These ease breathing by relaxing the muscles around the small airway walls – this drug is not a cure, but will only dilate the airways for as long as they are given.
       - Steroids: These improve the structure of the lungs by dampening down the over-zealous inflammatory reaction.
- Both are given orally or are inhaled
- Antibiotics are given to treat secondary bacterial chest infection and expectorants to shift mucus which allows inhaled drugs to reach the lungs
- Immunotherapy has been attempted to treat RAO but success has been limited
- Antihistamines are not effective
- Phenylbutazone (bute) should never be given due to it’s natural chemicals guarding against airway inflammation so it will worsen things