In cases of acute hog cholera the earliest and most pronounced lesions occur in the capillaries and smaller arteries. Larger arteries and veins are less frequently involved. The lesions consist of swelling and proliferation of endothelial cells together with retrogressive changes in them and in the other parts of the blood vessel walls.
The character and degree of these lesions seem to be dependent upon the virulence of the virus and, to some extent, upon the presence of secondarily invading bacteria. We believe that these lesions should be considered a principal feature of the histopathology of hog cholera.