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Feeding Horses with Recurrent Airway Obstruction (RAO)

Feeding our horses to keep them in the best possible health is the priority of most owners. We all know that fibre is important, but sourcing good quality forage when grazing needs supplementing can be a challenge for many of us, especially at certain times of the year. Hay that has been badly stored, has become wet or damp, or wasn’t ever of the best quality can undoubtedly have deteriorated by the time it is 10-12 months old. As a result, many horse owners struggle with dusty, poor quality hay resulting in respiratory problems for their horses.

Recurrent Airway Obstruction (RAO) is considered to be the most common respiratory disease in horses today and as many as 50% of horses over the age of Chronic Obstructive Pulmonary Disease (COPD), RAO is caused by an allergy to dust and mould spores commonly found in poorly made and stored forages and beddings. It is recognisable by a persistent cough (often at meal times or whilst being exercised) and is sometimes accompanied by a nasal discharge and apparent difficulty in breathing. It can often have implications on the performance of horses who are working harder.

Hay, straw and poorly managed bedding are probably the biggest offenders. The degree to which they are likely to be affected is dependent on the weather conditions when it was originally made, how it was stored and how old it is. When the mould and dust spores in these poor quality forages or beddings are inhaled, they cause an allergic reaction in the horse’s lower airway. This results in swelling and increased mucus production in the lungs leading to a reduction in airflow and causing the symptoms we are familiar with.

Unfortunately, RAO is a chronic condition meaning there is no complete cure and affected horses are likely to need specialist management for the rest of their lives. However, many horses can live perfectly normal, healthy lifestyles through management of the condition. The following steps can significantly reduce the symptoms exhibited by the horse:

  • Maximum amounts of turnout! If the horse can live out 24/7, the amount of dust/mould spores he is inhaling is likely to be minimal, meaning the symptoms will be greatly improved.
  • Soaking hay (if fed). It is thought there is very little UK-produced hay that is of good enough quality to be fed to horses long-term and not cause respiratory problems. Feeding soaked hay will mean the dust and mould spores are less likely to be airborne and inhaled. However, as soon as the hay dries, the spores will become a problem again. They are NOT washed out!
  • Stable ventilation. Ideally use a stable with direct access to the outside to ensure a constant supply of fresh air. Ensure all dusty cobwebs and dust accumulations are regularly removed from the stable. Also consider the bedding and forage of any adjoining stables if there is airflow between theirs and yours!
  • Bedding. Unless of an extremely clean, good quality, straw is unlikely to be an ideal bedding choice for horses suffering from RAO. Even if using shavings that claim to be dust-free, it is worth testing a bale first as many can prove to be far from this!


If 24 hour turnout is not possible, finding appropriate forage for a horse suffering from RAO must be a main priority. As very little hay is likely to be of a clean enough quality, soaking is the only option if this forage source is going to be used. However, whilst soaking undoubtedly provides a short-term solution, if the hay dries before the horse has finished eating, the dust and mould spores will immediately become airborne again, and are likely to cause a flare up of symptoms.

Another option is to consider feeding a bagged forage that is guaranteed to be 100% dust free – this is the ideal forage choice for horses suffering from RAO. Consider one that has FEMAS and BETA NOPS certification if you compete at a high level and are likely to be subjected to blood testing. Choose a variety which offers the energy level you require.  Good doers, those prone to laminitis and those in little or no work will require a lower calorie forage. For horses that are in harder work, or those who struggle to hold their weight and need to obtain a little more from their forage ration, choose one with higher calorie levels.  Alfalfa forage is ideal for individuals who need a little more still from their net. These could be broodmares in the final stage of pregnancy or early stage of lactation, horses working very hard, or those that really struggle to hold their weight.


Top Tips for Feeding Horses with RAO:

  • Turnout as much a possible
  • Use a 100% dust free forage
  • Ensure stables are kept clean and well ventilated
  • Use a bedding with minimal dust content


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