We all know that asthma is a common respiratory disorder in people but, did you know that horses get asthma too? 

“Equine asthma” is a broad term that has recently been used to describe a spectrum of non-infectious respiratory diseases in horses, previously known as broken wind, heaves, chronic obstructive pulmonary disease (COPD), recurrent airway obstruction (RAO), inflammatory airway disease (IAD) or bronchiolitis, amongst others.

Whilst the condition is well-recognised in the northern hemisphere, little is known about how commonly Australian horses are affected and what the potential risk factors might be.

This is why the University of Adelaide is asking you to participate in a study that will determine how common equine asthma is within the general Australian horse population.

If you are an Australian horse owner, . 

What causes Equine Asthma?

It is understood that environmental factors play a key role in the development of equine asthma. Exposure to airborne dust, moulds, fungal spores and pollens have all been found to cause an inflammatory effect in the horse’s lungs. In the northern hemisphere, the stable environment and feeding of dusty hay have been found to be key triggers whilst in parts of the southern hemisphere pasture-associated disease appears to be more common. However, the situation in Australia has received little study.

What are the signs of Equine Asthma?

Equine asthma can affect horses of all ages and may vary in severity considerably. Mild cases may show few outward signs of respiratory disease and can be easily overlooked. Such horses may show decreased performance or a reduced willingness to work without overt signs of respiratory disease. Other horses may have a clear or white nasal discharge and /or coughing. In the most severe cases affected horses will show signs of breathing difficulty whilst at rest. This can be seen as flaring of the nostrils (figure 1) and increased abdominal effort, which may ultimately result in the formation of a “heave-line” (figure 2).

A horse showing signs of nostril flaring
Figure 1: A horse showing signs of nostril flaring
A heave line can be a sign of equine asthma
Figure 2: A horse with a “heave-line”

How is Equine Asthma diagnosed?

We can get a good idea about whether a horse has equine asthma from the clinical signs that are reported by the owner. However, it is important to rule out other breathing problems (such as respiratory infections or upper airway obstructions) that may be mistaken for equine asthma. In people, a diagnosis of asthma is based on lung function testing. This is more challenging to perform in horses and so instead we look for evidence of mucus and inflammation in the lungs by performing an endoscopic examination (figure 3) and lung washes.

An endoscopic examination of a horse's airway
Figure 3: An endoscopic examination of a horse

How is Equine Asthma treated?

The cornerstone treatment for equine asthma involves environmental management to reduce the exposure to airborne dust and allergens. For stabled horses this can involve changing the type of bedding that is used, reducing respirable particles in hay by soaking or steaming, using alternative forage sources or moving the horse to pasture. If the pasture is the key trigger, then it may be necessary to move the horse to a different environment or to stable it. However, it should be noted that horses with pasture-associated disease are also likely to react to the stable environment and so it is important to minimise the environmental dust that they are exposed to within the stable as well.

For the majority of horses affected with equine asthma it is also necessary to treat medically in order to reduce the airway inflammation and restore normal lung function. As in humans, medical management of equine asthma includes corticosteroid therapy (indicated for its potent anti-inflammatory effects) and bronchodilators to help open up the airways. These drugs can be administered via inhalation just like in humans (figure 4).

Treating a horse with inhaled medication
Figure 4: Treating a horse with inhaled medication

Help us find out more about Equine Asthma in Australian horses!

At the University of Adelaide, we are currently conducting a study to determine how common equine asthma is within the general Australian horse population. In addition, we hope to identify the most important risk factors for the development of the disease in this country.

To help more Australian horses, help us with this study! The survey will take just 15 minutes to complete.

Your contribution to this study will help us to improve the welfare of Australian horses. Participants will have the option to remain anonymous unless they would like to enter the prize draw for completing the short survey!

The study is for Australian horse owners and open until the end of April 2020.

This study is being conducted by Miss Jewel Azaria Tan (Animal Science Honours student, The University of Adelaide), Dr Surita du Preez (Equine Internal Medicine, The University of Adelaide), Dr Samantha Franklin (Equine Sports Medicine, The University of Adelaide) and Dr Jackie Cardwell (Epidemiology, The Royal Veterinary College, UK).