Every cough a warning signal

Equine asthma is an umbrella term encompassing inflammatory diseases of lower airways in horses, formerly known as heaves and inflammatory airway disease¹. It is categorized into mild to moderate equine asthma which affects horses of any age, and severe equine asthma which is typically seen in horses older than 7 years of age. Studies show that up to 80 percent of horses in different populations may suffer from mild to moderate equine asthma², while severe equine asthma may affect as many as 11-17 percent of horses^3,4. Equine asthma can have a significant impact on a horse’s performance and quality of life. Over time severely asthmatic horses may develop changes in the lung, which makes it difficult to breathe, even at rest. So how can owners detect equine asthma early to help prevent the disease from getting worse?

Coughing can indicate early onset

Unfortunately, the mild to moderate form of equine asthma can be particularly difficult to detect. There aren’t many symptoms. To the unsuspecting eye, a mildly affected horse may still appear to perform well, e.g. in equestrian sports. They still have power and stamina – just not to their full potential. The most reliable indicator is coughing, even if infrequent. Other signs may include increased recovery time post exercise or a nasal discharge. “Mild to moderate equine asthma is difficult to recognize, so you need to look for these subtle signals, take them very seriously, and contact your vet as soon as possible,” explains Julius Krawczyk, Equine Technical Service Manager, Boehringer Ingelheim. “Because without a diagnosis and subsequent treatment, the condition can continue to affect the health of the horse, and compromise their airflow, making it difficult to breathe.” 

Equine asthma can take their breath away

Severe equine asthma is recognized most commonly by episodes of laboured breathing, even at rest. Horses suffering from this condition also have a chronic cough, nasal discharge and exercise intolerance. These more obvious clinical signs can be triggered by changes in the horse’s environment such as increased exposure to dust (primarily from mouldy hay), or by changes in weather, bedding, or stabling environment. 

Cause and effect

Equine asthma is caused by exposure to high concentrations of organic dust, especially the dust particles that are small enough to pass with inhaled air to the lower airways. Such particles are commonly found in hay and bedding. A subtype of severe equine asthma called summer pasture asthma is found in horses kept outside during grazing seasons, where pollens and air pollution as well as heat and humidity play a role in disease exacerbation.  

Treatment of equine asthma: it is as easy as
1-2-3

The key principles of treatment of equine asthma include 3 steps:

1. Removal of triggering factors through environmental modification
2. Addressing inflammation in the lung with corticosteroid therapy
3. Use of bronchodilators as necessary for fast relief of bronchospasm 

Be it a mild to moderate or severe case of equine asthma, the first thing to do when your horse is afflicted is to decrease exposure to triggering environmental factors. Decreasing dust exposure from hay and bedding is a key. This can be achieved by  feeding low dust options such as hay pellets or steamed hay, and by using  wood shavings instead of straw for bedding. Another option is to increase the turnout time so that the horse is outside, away from the dust of the stable area. Horses with pasture associated asthma will benefit from living inside well-ventilated, clean and low-dust stables. 

The cornerstone of medical therapy is to use anti-inflammatories to decrease the inflammation of the lower airways. This is best achieved by administration of potent glucocorticosteroids delivered directly to the lung  by inhalation. In certain cases, there may also be a need for bronchodilators in addition to environmental changes and cortisocteroid therapy. 

Effectively controlling the disease

When equine asthma is not well managed, it can be a threat to your horse’s  quality of life. By taking the right steps and closely working with your veterinarian, you can effectively manage the disease so that your horse can feel better, be more active, and breathe more easily.  

Footnotes

¹Couëtil, L.L., Cardwell, J.M., Gerber, V., Lavoie, J.P., Léguillette, R. and Richard, E.A., 2016. Inflammatory airway disease of horses—revised consensus statement. Journal of veterinary internal medicine, 30(2), pp.503-515.

²Ivester, K.M., Couëtil, L.L. and Moore, G.E., 2018. An observational study of environmental exposures, airway cytology, and performance in racing thoroughbreds. Journal of veterinary internal medicine, 32(5), pp.1754-1762

³Couëtil, L.L., Ward MP. Analysis of risk factors for recurrent airway obstruction in North American horses: 1,444 cases (1990-1999). J Am Vet Med Assoc 2003;223:1645–50. 

⁴Wasko, A.J., Barkema, H.W., Nicol, J., Fernandez, N., Logie, N. and Léguillette, R., 2011. Evaluation of a risk‐screening questionnaire to detect equine lung inflammation: results of a large field study. Equine veterinary journal, 43(2), pp.145-152.