Ventilation is the air flow allowing fresh air to enter and stale air to leave the stable or barn. The most effective ventilation is where the air flow can be replaced every hour and this is via windows, doors, openings and ventilation systems. If a stable is not properly ventilated there is increased risks of respiratory infections and allowing airborne infections to spread more easily. 

Ventilation in the summer months is important to keep your horses cool and comfortable in the warmer weather. In the winter months, ventilation is just as important as there is an increased risk of the build-up of moisture which allows pathogens to grow. In winter horses produce body heat after exercise as well as exhaling after each breath. It is vital that this moisture is circulated in the air and able to leave the barn for fresh air to enter.  If stables have ammonia and damp, there is a greater chance that organisms can survive. These pathogens can be found in damp storage areas, bedding and stables. Some possible risks of poorly ventilated stables include;

Increased risk of respiratory infections

Greater risks of pathogens surviving

Increased ammonia and bacteria living in the stables 

It is important that the construction of the barn is considered when looking at ventilation. For example air flow may be possible to enter but if there is not a way for the stale air to leave then the pathogens and bacteria will remain in the stable. Roof vents are important as they allow for stale air to leave the building.