Horses breathe over 70,000 litres of air per day and significantly more if exercised. Although highly specialised, the horse’s respiratory system is delicate and even small challenges can compromise health, welfare and performance. With ‘Love your lungs week’ upon us, what better time to talk about respiratory health?

Did you know?

-At rest the horse takes approximately 8-12 breaths per minute

-Horses only breathe through their nostrils (unlike humans who breathe though their mouth and nostrils)

-At canter and gallop, the horse takes one breath with every stride

-Horses hold their breath over a jump (and breath out when they land)

-The horse’s respiratory system does not respond to training (unlike the heart and skeletal muscle) – the amount of air the horse moves in and out of its lungs at a set speed does not increase with fitness

-Respiratory challenge has been identified as one of the most common causes of poor performances in athletic horses

Hay vs. haylage

All hay and haylage contains some degree of tiny dust, bacterial, mould and fungal spores called ‘respirable particles’ which are small enough for the horse to inhale. Although haylage is often thought of as ‘cleaner’, in reality the hygienic quality varies considerably and in some cases, may be no better than hay. Dryer haylages and those containing seed heads may be higher in respirable particles but with the exception of visible mould, it’s not possible to truly evaluate the hygienic quality of forage by eye and smell alone.

Hay soaking

Soaking hay (haylage should not be soaked) for just 10 minutes causes the large majority of respirable particles to swell so that they are swallowed rather than inhaled. However soaking can cause an increase in bacteria and fungi, particularly if you soak for extended periods. Hay also needs to be fed immediately after soaking as once dried, spores become airborne again.


Steaming is certainly the superior option when it comes to improving the hygienic quality of both hay and haylage. In addition to eliminating almost all of the respirable particles, high temperature steaming kills bacteria, mould and fungal spores. Steaming haylage also helps to extend the shelf-life after the bale is opened which can be useful for one horse owners.

Homemade steamers

Although homemade steamers do reduce the number of respirable particles, results are inconsistent. Homemade steamers also do not reach the high temperatures required to kill bacteria, mould and fungal spores and in fact, can act as incubator and increase contamination.

Respiratory supplements

Antioxidants and in particular vitamins C and E are a key part of the body’s natural defense against respiratory challenge. In fact, research has shown horses with Respiratory Airway Obstruction (RAO) have much lower levels of vitamin C in the fluid lining their lungs. The form of vitamin C in WINERGY Ventil-ate® (a supplement from our sister brand) has been scientifically proven to increase the level of vitamin C in the lung lining fluid and the surrounding blood vessels.


Good housekeeping

It’s important to remember that diet is only one factor affecting respiratory health and even the most hygienic of forages cannot compensate for other environmental challenges. These include choice of bedding and flooring, ventilation, air quality, pollen, travelling, reduced turnout and other stable management practices such as mucking out and the use of certain disinfectants.


For more friendly feeding advice contact the SPILLERS Care-Line