The avian respiratory system and its noninfectious disorders: A review

The avian respiratory system is well adapted to the manifold physiological requirements. The lungs are relatively small, though extremely functional. The main bronchus runs through the lungs to open in the air sacs. The ventrobronchi branches cranially from the main bronchus. More caudally, the dorsobronchi branches from the main bronchus. Then, the dorso-bronchi split to form the para-bronchi. The air sac walls in the pigeon (Columba livia) appear to consist of two perpendicularly arranged thin layers of connective tissue, covered with flat epithelium. Trauma, vitamin A deficiency and, hormonal unbalances are known to cause lesions in the respiratory system. On rare occasions, pathology of the trachea can be found. Aspirated particles of seeds or peanuts may lead to accumulations of fat in the main bronchus. More chronic irritation may lead the production of "Bronchiolar Associated Lymphoid Tissue". A variety of pathologies resulting in respiratory dysfunctions are described.