154 SWINE PRACTICE 



as a rule this produces little or no inconvenience to the animal and 

 is therefore of scientific interest only. 



STENOSIS 



Bronchial stenosis is rarely common in swine. The condition may 

 affect either the large or small tubes. Bronchial stenosis is probably 

 most frequently the result of a diseased condition of the bronchial 

 mucosa, such as catarrhal inflammation, ulceration, tuberculosis, para- 

 sitic invasion, or mechanical injury due to some foreign body, as a 

 needle or a nail. 



CATARRHAL BRONCHITIS 



The principal inflammatory disturbance of the bronchial tubes is 

 of a catarrhal nature, at least in the beginning. Catarrhal bron- 

 chitis may be either acute or chronic. 



Etiology. — Undue exposure to inclement weather is one of the 

 principal causes of bronchitis. Inhalation of dust-laden air is also 

 an important causative factor of inflammation of the bronchial tubes. 

 Infection is in many instances an auxiliary of other causes and 

 streptococci bacillus pyocyaneus are many times the primary causes 

 of bronchial • catarrh. This condition may be associated with other 

 diseases, such as swine plague or hog cholera. 



Chronic bronchial catarrh results from the action of the same 

 causative factors that produce acute catarrh, but the irritants are 

 usually less intense and act for a longer time. 



Lesions. — There is congestion of the affected mucosa, which later - 

 becomes covered with mucous or with a mucopurulent discharge. 

 In extreme cases the discharge may be tinged with blood and become 

 purulent. When the disease process involves the capillary bronchial 

 tubes there is usually more or less eiaphysema, due to obstruction 

 of the tubes with exudate which prevents the escape of air from the 

 air cells. There may be areas of atelectasis which project beyond 

 the surface of the lung and are of a darker color than the lung. 



Chronic bronchial catarrh is characterized by the presence of 

 mucous, purulent, or e\-en caseous material in the bronchial tubes, 

 and by fibrous proliferation in the submucosa which may result in 

 an attenuation of the mucosa. Dilatation or bronchiectasis is a com- 

 mon lesion, particularly in the dependent parts of the lung, in chronic 

 catarrhal bronchitis. In long-standing cases there may be peribron- 



