BUREAU OF ANIMAL INDUSTRY. 659 



attenuation, as practiced by Pasteur in obtaining a vaccinal virus for 

 anthrax and roiKjet. are inapplicable in tliis peculiar disease, for the 

 unattenuated virus itself is incapable of conferring immunity. The 

 experiments demonstrating this fact are found on another page. 

 Hence any attenuated virus is still less capable of accomplishing this 

 end. 



The use of certain medicines internally to act as preventives may 

 prove of some value, and it is our purpose to carry out some experi- 

 ments in this direction as well. 



The treatment of this disease, as of the great majority of infectious 

 diseases, after it has gained a firm hold upon the animal, is not only 

 useless but dangerous; for the animal can only serve to sjiread the 

 disease. The ulcerations produced in the large intestines can only 

 heal slowly if they are not too extensive, while medicines are of no 

 avail. Those who insist upon a cure for well-pronounced cases of 

 hog-cholera, in which the bowels have become ulcerated, should 

 look upon the disease of typhoid fever in man, in which ulceration 

 also occurs. Through centuries the best physicians have been treat- 

 ing this disease, yet none has ever ventured to assert that he had a 

 cure for these ulcerations. They take the best care of the patient 

 and allow nature to heal the ulcers. Even then they frequently find 

 their patient snatched away at the very threshold of recovery. 



PRELIMINARY INVESTIGATIONS CONCERNING INFEC- 

 TIOUS PNEUMONIA IN SWINE* (SWINE-PLAGUE). 



In prosecuting investigations in the West in order to determine 

 whether the disease which has been described in these reports as 

 hog-cholera existed there also, the lesions characteristic of this dis- 

 ease and the specific bacterium were found in Illinois and Nebraska. 

 At the same time another microbe was found, resembling in its mi- 

 croscopical characters the microbe of rabbit septicaemia very closely, 

 and associated with disease of the lungs — a chronic pneumonia — in 

 the few cases which were examined. Although the investigations 

 concerning the nature of this microbe, its distribution, ancl the losses 

 it produces, are scarcely begun, we venture the conclusion that it pro- 

 duces an infectious pneumonia in pigs, and that its effect may perhaps 

 be spent upon organs other than the lungs. This conclusion is based 

 upon the facts recorded in the following pages. 



Among the i^os^ ???orfew examinations made in the State of Illi- 

 nois in July, 1886, the following are worthy of attention: 



In Marion County, a few miles from Patoka, a herd was found, July 7, of which 

 about ten had died and an equal number were still alive. Thi-ough the kindness of 

 the owner several pigs, which were evidently diseased, were killed by a blow on the 

 head. In No. 1 the superficial inguinals were greatly enlarged; ecchvmoses were 

 found in the subcutaneous fatty tissue in large numbers on the omentum and the 

 epicardium. The lymphatic glands were as a rule enlarged and purplish, the spleen 

 augmented in size, the major portion of the lungs hepatized, and the remainder in- 

 terspersed with hemon-hagic foci. The mucous membrane of the stomach and the 

 large intestine was ecchymosed, that of the latter presenting here and there deep 

 ulcers, especially on the ileo-ca;cal valve. Cover-glass preparations from the spleen 

 of this case contained no bacteria of any kind. A tube of gelatine into which a bit 

 of spleen had been dropped remained sterile. No. 2, from the same herd, also killed 

 at the time, vvas affected with a suppurative pyelitis of the right kidnev, causing 

 inflammatory adliesions of the large intestine. The mucous membrane of the latter 

 vv-as dotted with innumerable petechife and a few ulcers. Cover-glass preparations 



*We shall call this disease swine-plague, ua distinction from hog-cholera, just 

 described. See introductory remarks to Diseases of Swine, p. 603. 



