Symptoms. Anatomical Changes. . 139 



In the cases terminating in recovery the animals become gradually 

 brighter, the cough becomes less frequent, the scabs fall off, the skin 

 regains its normal color, the appetite also improves, and the food is 

 utilized in the normal manner. Such animals are considered as re- 

 covered; according to Foth, however, this is not the case as the cough 

 never disappears entirely. On the other hand, animals which are 

 still sickly may, under new conditions, become again affected with the 

 acute manifestation, especially if exposed to cold in the presence of 

 digestive disturbances or after infections with virulent pathogenic 

 germs. In such relapses the animals usually die from pleural pneu- 

 monia or pericarditis (Hinrichsen). 



In pigs about 4 weeks old the course of the disease may be so 

 unfavorable that 50 to 80% of the affected animals succumb. On 

 the other hand, the mortality in older animals hardly ever exceeds 

 1 to 2%. The average loss is about 10%, while an additional 10% 

 remain runts. The majority, however, become only slightly affected 

 (Grips, Glage & Nieberle). 



The anatomical changes consist principally in a chronic broncho- 

 pneumonia, frequently associated with a sero-fibrinous inflammation 

 of the serous membranes. The autopsy reveals in the lower anterior 

 part of the lungs, either in a large portion or only at the borders, 

 wedge-shaped sharply circumscribed hepatized areas which have a 

 peculiar semi-solid consistency, or the organ may be similar to the 

 normal consistence of the pancreas (Joest). On the cut surface the 

 affected lung is grayish-red, smooth, moist or somewhat dry, and studded 

 with yellowish spots. At the same time the pleura over the correspond- 

 ing areas is lusterless and rough or covered with fibrinous membranes 

 which cause adhesion of the anterior lobes, and also with the costal 

 pleura. Between the pleural layers a reddish-yellow fluid may be 

 present in small (juantities which may also contain fibrin-coagulums. 

 Similar inflammatory changes are not infrequently found also on the 

 pericardium. The recovered cases often show only adhesions of the 

 serous membranes, some atelectic areas on the borders of the lungs 

 and hardening of the thoracic lymph glands. The bronchi are usually 

 filled with a muco-purulent secretion. 



In some of the cases the affected areas of the lungs contain 

 greenish purulent foci, and such may also be found in other organs 

 (see pyobacillosis, page 141). 



According to the histological exaniinations of Liipke and Joest the changes 

 in the lungs are, at the incipient stages of the disease, those of a typical catarrhal 

 pneumonia, while later the productive granulating character becomes more and more 

 prominent in which cell forms predominate such as are found in inflammatory 

 granulation tissue. 



The bacteriological examination always reveals various kinds of 

 bacteria in the affected parts of the lungs. The bacillus suisepticus is 

 present in about two-thirds of all cases. Fre(iuently, however, they are 

 few in number and of a very slight virulence, so that it is possible 

 to kill test animals only with large quantities of suspected material. 

 Simultaneous with this bacillus, but occasionally^ without it, streptococci 

 and staphylococci, coli bacilli, bacillus pyocyaneus, further in about 

 60% of the cases the bac. pyogenes suis may be found. 



The varying bacteriological findings and especially the frequent absence of 

 the bacillus suisepticus in the pne^-imonic tissues make its exclusive primary 

 etiological importance very doubtful. It appears more probable that the pneun:onia 



