150 



Biological Therapy 



POST-MORTEM LESIONS. It is now generally agreed 

 that the only lesions caused by the filterable virus of cholera 

 are those of an acute seiDticemia, viz.: hemorrhages and 

 petechia. Whenever extensive lung or intestinal lesions are 

 observed we must conclude that bacteria acting as secondary 

 invaders are responsible for the same. In many cases thes^3 

 secondary lesions are caused by bacteria which were present 

 in the body but which were not capable of causing pathologi- 

 cal changes until the filterable virus of hog cholera has 

 broken down the natural resistance of the host. 



Button ulcers of the intestinal tract were at one time 

 considered diagnostic of cholera. It is now known that these 

 cannot be depended upon for diagnosis because while they 

 are frequently present in cholera-sick swine they are also 

 found in animals which were apparently healthy before 

 slaughter. They are caused, not by hog cholera virus, but 

 by bacillus suipestifer. 



Petechiation of various organs has long been the sheet- 

 anchor in hog cholera diagnosis. While this still continues 

 to be our most dependable lesion, even here our examination 

 must be most thorough and our understanding of the lesions 

 of allied diseases complete, since it is now realized that the 

 same, or lesions apparently identical, may be caused by fac- 

 tors other than hog cholera virus. These minute hemor- 

 rhages may be caused by acids, by an excess of oily food and 

 by many septicemias other than cholera. 



Notwithstanding this, petechiae continue to be diagnos- 

 tic of hog cholera when found in outbreaks in which the 

 history and symptoms indicate cholera, particularly if the 

 petechiae he circumscribed and unifor^n in size. 



While petechiae of the kidneys, bladder, lungs and heart 

 may be present alike in hog cholera and hemorrhagic sept 

 cemia this does not apply to the lymphatic glands and the 

 ileocecal valve. In conditions other than hog cholera the 

 glands may be enlarged and engorged or the valve, as well 

 as other parts of the intestines, may be diffusely hemorrhagic, 

 but when the lymphatic glands and ileocecal valve show 

 well-marked petechiae a diagnosis of hog cholera is reason- 

 ably safe. For this reason our examination of these two 

 should be most searching. Glands, particularly the mesen- 

 teric and inguinal, should be thoroughly sectioned and the 

 crest of the ileocecal valve carefully examined for the pres- 

 ence of these diagnostic petechiae. Petechia of the trachea 

 and epiglottis may be present in both cholera and hemor- 

 rhagic septicemia, so that this cannot be relied upon. 



