Last Updated on March 18, 2022 by Allison Price

Chronic obstructive lung disease (COPD), also known as “broken wind”, is a chronic condition in horses that involves an allergic bronchitis. It is characterised by wheezing and laboured breathing, coughing (usually related to exercise or eating), and nasal discharge (especially if the head is lowered after exercise).

This condition is known as “heaves” because horses suffering from COPD have narrow, inflamed airways. As such, breathing in and out becomes difficult. Horses with COPD need to recruit abdominal and chest muscles to assist with respiration. These muscles then become larger and the horse develops “heaves”.

COPD can be caused by an allergic reaction to certain substances that are otherwise harmless. These allergens include dust, mould, and fungalspores (e.g. Aspergillus). It is most prevalent in horses that are fed straw and hay. It is very similar to asthma in horses and farmer’s lungs in humans.


Horses become allergic to allergens that enter their lungs. The horse’s hypersensitive immune response over-reacts against “normal” pollens. The horse’s lungs become inflamed, swollen and the mucus production increases.

The results of a clinical examination and auscultation of horses’ lungs are usually used to diagnose the problem. Sometimes, however, additional diagnostics may be required. In these cases, an endoscopic examination of the horse’s trachea or bronchioles and collection of samples can be done.

An acute flare-up can be very severe. Your horse may experience a markedly increased respiratory rate, effort, flared nostrils, and excessive sweating. The most important thing to do if your horse is suffering from severe dyspnoea (difficulty breathing), is to remove it from the stable or barn and give it fresh air. You must keep your horse calm and call your vet immediately.

The goal of treatment is to manage and minimize allergen exposure. The symptoms should subside once the allergens have been removed. However, they can recur if the horse is again exposed to the allergens. Even short periods of re-exposure can cause acute episodes.

If stopping stabling is impossible, the following modifications will be beneficial:

* Maximize air quality and minimize dust in the stable. To remove most allergens and pollens from hay that you will be feeding, soak it for at least an hour. The carbohydrate content of the forage will be reduced if the hay is soaked for longer. This is good news for horses and ponies with COPD or who suffer from laminitis.
* Any mucus that is accumulated in the lungs can be drained by eating from the ground. Horses are meant to graze for 20 hours per day. During this time, the horse’s head is down to the ground so that mucus can drain out of the bronchioles and trachea.
* Use dust-free bedding. Horses that need to be stabled must be able to sleep on rubber mats and paper or low-dust wood shavings. Straw is not recommended as it can cause dust, moulds, and fungal spores. Horses may become allergic to certain bedding, in which case it can be washed every day. Although the initial cost of matting is high, it can save you a lot in bedding and veterinary expenses if your horse has RAO.
* Make sure that the stable is well ventilated.
To reduce dust buildup, don’t clean up or muck out your horse while he is in the stable.

If the environment is high-risk for horses, all the stables nearby must be maintained in a similar manner. Try to keep your horse out of the mud heap.

Even with management changes, medications are often necessary. These can be broken down into three broad categories.

* Bronchodilators: These dilate (open the bronchioles) and allow the horse to breathe more freely.
* Corticosteroids: These reduce inflammation in the airways, and dampen the immune hypersensitivity reaction.
* Anti Histamines: These are used to reduce the immune hypersensitivity reaction that causes inflammation in the lungs.
* Mucolytics: These make horse’s mucus viscoseier and easier to remove from the airways.

All drugs used in competition horses should be treated with caution, as they are often prohibited substances under racing rules and FEI rules.

The condition is called summer pasture associated obstructive lung disease (SPAOPD). This is because the allergens are derived directly from the pasture. This condition is more common in summer and should be managed by horses being kept in well-ventilated areas. Horses can develop RAO or SPARAO, which can make it very difficult to manage.

RAO can often limit horses’ ability work and make strenuous activities difficult. The condition can be treated with prompt diagnosis.

Allison Price
Allison Price

I’m Allison, born and raised in San Diego California, the earliest memory I have with horses was at my grandfather’s farm. I used to sit at the stable as a kid and hang out with my Papa while he was training the horses. When I was invited to watch a horse riding competition, I got so fascinated with riding!