ACUTE TRACHEITIS AND BRONCHITIS 35 



stances by the bronchial mucosa causes a rapid proliferation 

 of the surface and granular epithelium of the mucous mem- 

 brane and an increased secretion of mucus. The epithelium 

 of the mucous membrane becomes more embryonal in char- 

 acter and therefore less resistant to the invasion of micro- 

 organisms. At the same time these organisms, ordinarily 

 present, multiply more rapidly and increase in virulence, and 

 unless the process is arrested a bronchitis is soon established. 

 Some drugs (iodin, bromin, etc.) when administered in large 

 doses and continued for quite a time may be excreted in 

 sufficient quantities to produce an acute bronchitis. 



(c) Inhalations of smoke containing various gases and 

 particles of foreign material will irritate the mucous mem- 

 brane of the entire respiratory tract, frequently resulting in 

 an active congestion and later in inflammation of the mucous 

 membrane which favors the growth and development of the 

 infection which is always present. 



(d) Acute bronchitis develops frequently as a secondary 

 disease following specific infections (distemper, etc.). The 

 specific infection reduces the normal resistance of the mucous 

 membrane thus allowing the secondary infection (staphylo- 

 coccus, streptococcus) to develop rapidly and produce the 

 disease. 



(e) Parasitic. In severe infestations of the Uncinaria 

 canina, the larval form of this parasite, in its migrations 

 through the body, often burrows along or through the walls 

 of the bronchi and trachea producing an inflammation of the 

 mucous membrane and the underlying tissues. (See Unci- 

 nariasis.) 



(/) Tracheitis and acute bronchitis are often consecutive 

 to inflammations of the nasal passages, larynx and pharynx. 

 The infection is carried to the trachea and bronchi by inhala- 

 tion where it develops, producing the inflammation. 



(g) Other diseases (renal affections, endocarditis, diabetes, 

 carcinomas and sarcoma, valvular insufficiency) produce a 

 disturbance of the heart action, enfeeblement of the vaso- 

 motor nerve and reduce the resistance of the mucous mem- 

 brane. 



It is quite evident that acute tracheitis and bronchitis 



