THE RESPIRATORY SYSTEM 91 



tubercle bacillus are the most frequent causative factors 

 of this condition. These organisms may be inhaled 

 direct but they are more frequently introduced into the 

 lung from elsewhere as emboli. Purulent pneumonia in 

 old swine is therefore frequently associated with pyemia, 

 abscess formation, or purulent metritis. Several cases 

 have been observed in the carcasses of swine that had 

 previously been hyperimmunized intramuscularly for the 

 production of anti-hog-cholera serum. 



Lesions. The principal lesion is suppuration, the 

 centers of which vary in size and number but in the 

 beginning are relatively small and in the earlier stages are 

 not encapsulated but are surrounded by a zone of lung 

 tissue intensely infiltrated with cells. As the condition 

 progresses a circumscribing capsule is formed and the 

 pus becomes thicker, and if the capsule is not destroyed 

 the contained pus becomes caseous and may later become 

 calcified. Should the capsule of a suppurative center 

 become eroded the contained pus may infiltrate the 

 adjacent lung tissue or discharge into a bronchial tube, 

 the original suppurative center thus becoming a cavity. 

 The pleura covering superficial suppurative centers 

 usually shows some involvement. 



Symptoms. The evidence of purulent pneumonia 

 varies according to the nature and extent of the lesions. 

 The presence of a single abscess may not cause any 

 noticeable symptoms. General embolic purulent pneu- 

 monia is characterized by intense symptoms consisting of 

 chills, fever, difficult and hurried breathing, uneasiness, 

 and general distress. The discharge of pus within the 

 lung tissue is evidenced by rise of temperature and the 

 associated cardiac and respiratory disturbances. 



Treatment. No special line of treatment is of 

 value. The animals should be placed in good quarters 

 and cared for properly. 



Septic or Gangrenous Pneumonia 



Septic pneumonia is relatively common in swine. It 

 has occurred enzootically in swine affected primarily 



