DISEASES OP RESPIRATORY ORGANS 



167 



limited amount, and in other cases the normal lung tissue is dis- 

 placed by fibrous tissue. Encapsulated suppurative or necrotic cen- 

 ters may be found. 



Symptoms. — A persistent cough, associated with) a limited but 

 variable nasal discharge of a mucopurulent material, characterizes 

 chronic pneumonia. The animals are usually unthrifty and 

 emaciated. 



Section of 



bronchial tube 



showing 



lung worms 



Pearly spot 

 caused by 

 infestation 

 with lung 



Pig. 32. Lung of liog with lung worms. (Ostertag.) 



Treatment. — The cause should be removed and the animals properly 

 housed and fed. Other than this, little can be done. 



TUMORS 



Various tumors have been encountered in the lungs of swine, but 

 principally in autopsies or at abattoirs. Lung tumors of swine are 

 similar to the same type of tumors of other tissues. Pulmo-nary 

 nepolasms produce no typical symptoms by which they may be recog- 

 nized clinically. 



