Pneumonia Associated with Inhaled Plant Material in Swine

A high incidence of foreign-body pneumonia was found in an institutional swine herd. Foreign material of plant origin was found in 40 of 68 lungs. Most of the foreign matter was of feed origin but four particles of wood were demonstrated. Numerous particles up to 50 μm wide were found in alveoli, and particles as large as 300 μm were found in bronchioles. Lungs of four control animals were used to study the histological reaction to the inhaled foreign bodies. Polymorphonuclear leucocytes, macrophages, and giant cells were the principal cell types associated with the plant particles. Hyperplasia and destruction of respiratory epithelium and lymphoreticular proliferation were also noted.