278 BACILLI OF THE TYPHOID GROUP 



introduced from Europe, but abroad it is claimed that hog cholera 

 originated in America and was from there transported to Europe. 

 The hog cholera bacillus was discovered in 1880 by Salmon and 

 Smith, and was by them proclaimed as the cause of the disease. The 

 losses from this affection in the United States are enormous and are 

 estimated at from ten to twenty-five million dollars annually. They 

 are also very great in England, France, Austria, Russia, Germany, and 

 other smaller European countries. 



Pathologic Lesions. The pathologic changes are described by 

 Dorsett, Bolton, and McBryde as follows: "The changes seen in the 

 internal organs vary greatly even in different animals in one and the 

 same outbreak in a given herd. In general, these lesions may be said 

 to be either those of a hemorrhagic septicemia or of an ulcerative 

 enteritis, the latter particularly pronounced in the cecum and colon. 

 The hemorrhagic lesions are characteristic of the rapidly fatal form 

 of the disease known as acute hog cholera, the ulcerative intestinal 

 lesions being especially prominent in those outbreaks where the 

 animals do not succumb so rapidly; both the ulcerative and hemor- 

 rhagic lesions may, however, be seen in the same animal. When the 

 skin of the thorax and abdomen is removed the subcutaneous areolar 

 tissue may be found thickly dotted with ecchymoses of varying size. 

 In acute hog cholera the inguinal glands on both sides are usually 

 swollen and red, the hemorrhagic condition being so intense at times 

 as to give the glands a bluish-black color. The lymphatic glands 

 at the angles of the lower jaw may be affected in a similar manner, 

 as may also the bronchial, mediastinal, mesenteric, mesocolic, retro- 

 peritoneal, and lumbar glands. In the chronic form of the disease 

 the lymph glands seldom exhibit any change. The heart frequently 

 presents at its outer surface, and also in the endocardium at times, 

 hemorrhagic markings. The lungs, as a rule, are but slightly affected. 

 In the acute form of hog cholera they often show ecchymoses of 

 varying size on the serous surfaces; at times areas of bronchopneu- 

 monia or collapse are met with. In acute hog cholera the spleen, 

 as a rule, is larger than normal, and engorged with blood, and may 

 present numerous punctiform hemorrhages beneath the capsule, or 

 larger hemorrhagic areas which are diffuse in character. In chronic 

 hog cholera the spleen may be smaller than normal, and in 

 this case the connective tissue is noticeably increased. The serous 

 surface of the stomach may be flecked with diffuse hemorrhages, 

 and the mucosa is not infrequently congested and inflamed. This 

 inflammation is at times quite extensive, and may bring about 

 destructive ulceration of the mucous membrane. Small petechise 

 may be seen here and there over the mucous membrane. In acute 

 hog cholera the chief lesions found in the intestines are ecchymoses 

 in both serous and mucous coats, together with erosions of the mucous 

 surfaces of both the large and the small bowels. The erosions in 

 the cecum and colon appear to be the starting point of the button-like 



