Lower Respiratory Tract Disease

By Lauren Lamb

The lower respiratory tract of a horse consists of the lungs and the small tubes running throughout the lungs (bronchi, bronchioles and alveoli). The lungs’ primary function is to absorb oxygen from the inhaled air and expel carbon dioxide in the expelled air. The gas exchange takes place at the alveoli, which is located at the end of the small bronchioles.

The air that is inhaled is anything but sterile. It contains a large amount of bacteria, fungus, dirt, pollen and other miscellaneous contaminates that put the lungs at severe risk of developing inflammation and/or infection. In order to combat these high levels of contamination, the lungs are equipped with a very sophisticated and unique immune system that helps prevent inflammation and infection.

The immune system/protective mechanism starts in the upper respiratory tract (nasal passage and throat) which filters, humidifies and warms the inspired air. The entire lower respiratory tract is also covered with a thin, sticky layer of mucus which contaminates from the air will stick to as the air travels from the nostril to the lungs.

Read the August issue of OKFR to learn more about this disease.