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The Horse's Airways: The Effect of Roughage on Health and Function

High-quality roughage forms the basis of the diet of the horse. The horse's daily energy intake is mainly derived from digesting fibre provided through roughage. However, unhygienic roughage, of low quality, can contain a lot of dust that the horse's respiratory tract cannot tolerate. As a result, horses can develop chronic diseases that then affect the horse's general health and performance.

The Horse's Respiratory System

The horse's respiratory system consists of the nose, mouth, pharynx, larynx, trachea, bronchi, alveoli and lungs 1. The respiratory system functions to supply oxygen and eliminate carbon dioxide from the body. When the horse breathes, the horse breathes in about 4 to 5 litres of air 2. However, the total capacity of the lungs is much larger, about 42 litres 3. The body requires oxygen to produce energy. Energy is important for maintaining the body, metabolic processes and acts as fuel for the muscles when the horse exercise. When a horse starts to move, its body requires more oxygen, leading to increased breathing 4. Research has shown that walking and trot have little effect on the horse's breathing. Mainly canter affects respiration and causes the horse to inhale more air 5.

The Effect of Roughage on the Horse's Respiratory System

The horse's airways are also an important part of the immune system. The airways are part of the innate immune system, which is the first to react to the entry of pathogens. When pathogens enter the airways, the body responds to render them harmless 6. When small (dust) particles enter the airways this will therefore trigger an immune response, affecting the respiratory system’s health. Poor quality forage can contain a lot of dust which the horse then inhales.

Larger dust particles entering the respiratory tract are cleared by the respiratory system. Dust particles that are smaller end up in the alveoli where they then cause an inflammatory response 7. In the alveoli, the exchange of oxygen and waste products takes place and thus has an important function in the body. Inhaling small dust particles, for example from poor-quality roughage, affects the health of the horse's airways which then causes symptoms such as sneezing or coughing.

Dust does not affect the health of the respiratory tract if the horse is exposed to dust for no longer than 5 to 7 hours 8. If the horse is moved to a cleaner environment promptly, its airways can recover. But if a horse inhales dust from the environment for a longer period of time, which irritates the airways, there is a chance of the horse developing a chronic respiratory disease 9. Symptoms of chronic respiratory disease include coughing, sneezing, excessive mucus production, reduced performance and increased breathing.

Roughage and Management to Support Respiratory Health

Because roughage forms the basis of the horse's ration it is an important part of the diet. There are different types of roughage such as hay, silage, alfalfa and beet pulp. In addition, the quality of roughage varies. As mentioned earlier, poor-quality roughage can contain a lot of dust which affects the horse's respiratory system. Therefore, it is important to ensure that the roughage you feed your horse is of good quality. There are also several ways to ensure that roughage is less dusty.

Instead of hay, which is more likely to contain more dust because it is drier, you can opt for silage. Silage is a type of roughage that is partially dried after cutting grass and then packed in plastic 10. A fermentation process takes place in silage under the influence of oxygen which is inhibited by wrapping it in plastic. Because silage does not dry as long as hay, silage contains more moisture, which means the dry matter content is lower and the roughage contains less dust 10. Silage is therefore a good alternative for horses with respiratory complaints and who are sensitive to dust or to prevent complaints.  

Adjustments to the horse's management will prevent respiratory diseases and issues or reduce the symptoms of horses with chronic symptoms. Sometimes it is not possible to select high-quality roughage and the roughage still contains a lot of dust. A commonly used management method is to soak roughage in water to reduce the amount of dust. While this method does indeed reduce dust in the roughage, it also reduces the amount of nutrients in the feed and increases the amount of bacteria 11. Studies have shown that steaming hay is a better option to reduce dust in the roughage and also ensure that the roughage retains nutrients 12.

In conclusion, it is important to keep the horse's environment as hygienic as possible and ensure that the horse can breathe in as little dust as possible. There are several ways to reduce dust in the horse's environment and roughage. This has a positive effect on the horse's respiratory health and performance.



1.     Lekeux, P., Art, T., & Hodgson, D. R. (2014). The respiratory system: Anatomy,

physiology, and adaptations to exercise and training. In Hodsen, D. R. & Rose, R.J. The

Athletic Horse: Principles and Practice of Equine Sports Medicine: Second Edition. WB

Saunders: Philadelphia, USA.

2.     McGorum, B. C., Ellison, J., & Cullen, R. T. (1998). Total and respirable airborne dust

endotoxin concentrations in three equine management systems. Equine Veterinary

Journal, 30(5): 430-434.

3.     Robinson, N. E. (2003). Chapter 2 - How horses breathe: The respiratory muscles and

the airways. . In: McGorum, B. C., Dixon, P. M., Robinson, E. N., & Schumacher, J.  (Eds.)

Equine Respiratory Medicine and Surgery. Saunders Elsevier: China.

4.     Franklin, S. H., van Erck-Westergren, E., & Bayly, W. M. (2012). Respiratory responses to

exercise in the horse. Equine Veterinary Journal, 44(6): 726-732.

5.     Robinson, N. E. (1985). Respiratory adaptations to exercise. The Veterinary Clinics of

North America. Equine Practice, 1(3): 497–512.

6.     Ganesan, S., Comstock, A. T., & Sajjan, U. S. (2013). Barrier function of airway tract

epithelium. Tissue Barriers, 1(4): 1-9.

7.     Auger, E. J., & Moore-Colyer, M. J. S. (2017). The Effect of Management Regime on

Airborne Respirable Dust Concentrations in Two Different Types of Horse Stable

Design. Journal of Equine Veterinary Science, 51: 105-109.

8.     Leclere, M., Lavoie-Lamoureux, A., & Lavoie, J. P. (2011). Heaves, an asthma-like disease

of horses. Respirology, 16(7): 1027-1046.

9.     Séguin, V., Lemauviel-Lavenant, S., Garon, D., Bouchart, V., Gallard, Y., Blanchet, B.,

Diquelou, S., Personeni, E., Gauduchon, P., & Ourry, A. (2010). Effect of agricultural and

environmental factors on the hay characteristics involved in equine respiratory disease.

Agriculture, Ecosystems and Environment, 135(3): 206-215.

10.   Clements, J. M., & Pirie, R. S. (2007). Respirable dust concentrations in equine stables.

Part 1: Validation of equipment and effect of various management systems. Research in

Veterinary Science, 83(2): 256-262.

11.   Moore-Colyer, M. J. S. (1996). Effects of soaking hay fodder for horses on dust and

mineral content. Animal Science, 63(2): 337-342.

12.   Moore-Colyer, M. J. S., Taylor, J. L. E., & James, R. (2016). The Effect of Steaming and

Soaking on the Respirable Particle, Bacteria, Mould, and Nutrient Content in Hay for

Horses. Journal of Equine Veterinary Science, 39 39:62-68.




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