Equine Asthma

Scratching bay horse

Equine Asthma

What is it? – The Terminology


Equine asthma was previously known as heaves, recurrent airway obstruction (RAO) or inflammatory airway disease.
It is a common, non-infectious and non-contagious respiratory condition caused by an allergic response to inhaled allergens found in the horse’s environment.


Allergens are normally harmless substances such as; mould spores, dust and storage mites or grass, weed and tree pollens. However, in an allergic horse, their immune system views these allergens as a threat, causing it to overreact, which in turn results in the symptoms we see.


Equine asthma is more commonly seen in stabled horses, but a pasture associated version also occurs.


It is a life-long and normally progressive condition, but the earlier a diagnosis can be made, before permanent changes have happened to the airways, the better.


Common equine respiratory allergens


List of indoor and outdoor Equine Allergens.


What does it look like? – The Symptoms


The airways become inflamed, and therefore narrower, in horses with asthma. This can result in respiratory noise. Alongside this there is an increase in mucus production causing the horse to cough as they try to clear it.


Equine Allergen symtoms chart.

How do I know if It’s Asthma? – The Diagnosis


The other common causes of similar respiratory symptoms, particularly infections, will need to be ruled out by your vet before a diagnosis of asthma is made.


This is likely to involve taking a detailed history (to work out if it could be triggered by allergens) and a full clinical examination. In many cases further diagnostic testing, such as blood tests and endoscopy, may be required depending on what is found.


What can I do to help? – Treatment


Allergen Avoidance


After the diagnosis has been made, the problem allergens can be identified either by skin prick testing or blood testing. These tests are comparable but many owners prefer the blood test as it can be done by their own vet, is quick and simple and generally has no requirement for sedation or clipping.


Changes in management to avoid these problem allergens is critical. Practical solutions to help achieve this vary depending on what the triggers are. Keep an eye out for our upcoming blogs on how to manage both indoor and outdoor allergens, or click here for more information.




Additional therapies are sometimes necessary to complement the allergen avoidance, especially for those horses which are severely affected, cannot have significant changes made to their environment, or have had the condition for a long time.


Equine therapies chart.




If you think your horse may be asthmatic, contact your own vet to discuss your concerns and ask their advice on the next step to help!

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