Bacterial infections of the lung

摘要

The upper respiratory tract of the dog is not sterile, but is actually colonized by a variety of bacteria that do not cause disease under normal circumstances. The lower respiratory tract, on the other hand, is usually free of bacteria in normal dogs. Normally the pulmonary defense mechanisms are extremely effective, and are able to guard the animal against attack by invading bacterial challenges. There are two circumstances under which bacterial invasion of the respiratory tract, and a resulting inflammatory response (infection), can occur.