Swine Plague : Septicemia Hemorrhagica Stiis. 49 



Abandonment by swine is, however, insufficient : all susceptible 

 animals, wild and tame, (see pathogenesis) must be excluded as 

 any one of these may maintain the infection. The preservation 

 of recovered swine on the premises, or the early return of the 

 immune may become a means of preserving the bacillus for the 

 next susceptible pigs that may be introduced. The bacillus of 

 swine plague ma} r be found on the air passages of swine and 

 other animals that are not themselves, at the time, susceptible to 

 the disease, and these animals accordingly become the occasions 

 of what have been thought to be spontaneous outbreaks, and of 

 invasions of fresh herds after the introduction of healthy pigs 

 which have been thought to be beyond suspicion. The danger 

 of the communication of the germ by wild birds and rodents 

 would be enormous, but for the fact that it is so much more 

 deadly to these animals than the microbe of hog cholera, that few 

 suivive to maintain the infection. Yet the rule ought to be, to ex- 

 clude from the fields or premises occupied by new or susceptible 

 pigs, all animals, that may by any possibility become the means 

 of introducing the infection so recently prevalent. Though so 

 easily destroyed when outside the living body, the microbe of 

 swine plague can be carried by the apparently healthy living 

 animal and we must rigidly exclude the possibility of this occur- 

 ring. 



Lesions. Acute and rapidly fatal cases of swine plague furnish 

 lesions indicative of a haemorrhagic septicaemia. The abundance 

 of petechias on the skin, mucosae, serosae, and tissues generally, 

 with circumscribed haemorrhages, congestions, inflammations and 

 exudations, agree in the main with what is observed in the acute 

 examples of hog cholera. If the congestive or inflammatory 

 lesions, concentrate in the lungs rather than the bowels it assists 

 in the diagnosis of swine plague. The swelling and blood- 

 engorgement of the lymph glands are nearly alike in the more acute 

 types of the two diseases. The spleen is less constantly enlarged 

 than in hog cholera or swine erysipelas. In the subacute and 

 chronic forms the lesions may be almost entirely confined to the 

 enlarged and congested or haemorrhagic lymph glands. Usually, 

 however, the lungs are the seat of lobular or lobar pneumonia, 

 affecting by preference the lower portions of the anterior and 

 median lobes, and sometimes also the posterior lobe. The ple- 

 4 



