Coughing and equine asthma

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Winter is a time when we often hear our horses coughing more.  Whilst in many situations this is not a major issue, in others, especially middle aged to older horses, this could be due to a disorder called equine asthma. Signs tend to be noticed more in winter as horses spend more time indoors. This exposes them to more of the potential allergens causing the disease.

What is equine asthma?

Equine asthma a non-infectious inflammatory airway disease triggered by environmental allergens such as fungal spores found in hay and straw.  It has previously been called Recurrent Airway Disease (RAO) or sometimes called Chronic Obstructive Pulmonary Disease (COPD).  It is also referred to as heaves or broken wind.  The airway inflammation results in the lower airways in the lungs narrowing due to constriction of muscles and build up of mucus making it harder for your horse to breathe. It typically affects stabled horses and is uncommon in young horses. Horses normally show a gradual worsening in signs, however,  acute episodes can occur, often in winter.  Equine Asthma can normally be easily controlled with management changes and either oral or aerosolized medication (similar to human inhalers).

Signs that your horse has asthma

  • Coughing (may only be when exercised or after feeding)
  • Noisy breathing (wheezing)
  • Fast breathing rate (look at the flank and see how many times in a minute your horse breaths, should be between 8-20)
  • Using abdominal muscles to assist breathing (flank markedly moves in and out with breathing)
  • Nostrils flaring.


The clinical signs of asthma may be classic, and further testing following initial veterinary examination may not be required. However, in more subtle cases, or when all of the signs are not obvious, testing will usually involve endoscopic examination of the airways (a small camera is inserted via the nostrils into the trachea) and then sampling of the material in the airway.  This will help rule out an infection, and also ensure that the correct diagnosis has been made.


Once a diagnosis is made, a management plan can be provided by your veterinary surgeon. Many horses will not need any medication once the initial signs are controlled if management changes to minimize the amount of dust and mould in the environment can be made. Some of these include:

  • Dust free bedding – replace straw with alternatives such as newspaper or dust extracted shavings. Regular shavings can be just as dusty as straw so check before you use them.
  • Haylage or steamed/soaked hay – steaming hay using commercially available steamers has been shown to be the most effective way of lowering numbers of mould spores and dust. Soaking the hay can prevent dust and allergens being released into the air when your horse eats, although soaking for too long can actually increase the amount of mould/fungal spores.
  • Turn out – even in the colder weather, turning horses out for as much of the day as possible gives them a break from the allergens present in the stable. If possible the horse should live outside all the time.

If your horse has not improved with these changes alone, medication can be considered in consultation with your vet.

Short term medication

Bronchodilators – these drugs open up the airways which become narrow with the disease. This allows more air to get in and out of the lungs. The drug mostly used is called clenbuterol.

Steroids – may be considered in more severe cases. These drugs prevent the horse’s immune system from over-reacting to stable allergens, again helping them to breathe better.

Long term medication

Aerosolized medications– similar to human inhalers these can be used to give your horse certain medications ensuring that they reach the lungs where they are most needed. These can come in the form of devices that cover one nostril, or masks that cover both nostrils, and are specially designed to ensure that the medications are effectively delivered to the lungs.


Asthma cannot be cured, but most horses can be managed very effectively and can continue to do their job. Ongoing consultation with your vet may be necessary if medication/management are no longer be as effective.