The farmer, and for that matter the public in general, should bear in mind that the cause of hog cholera is a living organism capable of enormously rapid self-multiplication--actual, though very minute particles of matter. This, fully understood, makes it apparent that infection may be carried in any way that other fine particles of matter may be carried. It thus becomes very apparent that the infection may be carried by sick hogs or upon the legs and bodies of hogs not sick; it may be carried in wagon boxes, in hog racks, in stock cars, or upon shoes and clothing of people. It is very evident that the infection may be carried down stream, especially in small creeks, and give rise to other outbreaks.
So far as the sick hog is concerned, we are quite sure that the blood and the manure are thoroughly infectious and there can be no question concerning the infectiousness of fresh carcasses of dead hogs. Perhaps we should say first of all that we rarely get all of the accepted symptoms of hog cholera plainly shown in one case. It is important to bear in mind that cases vary in virulence from those of very chronic type where hogs live for weeks and finally die or recover, to very acute cases where they die overnight.
The hog coming down with cholera is usually sluggish at first, lying around in the shade and refusing feed. The hair may become rough. The eyes early show symptoms of inflammation, with a sticky discharge. There is usually a suppressed cough. The gait may become irregular and uncertain, especially with the hind legs. After these preliminary symptoms have been shown for a time, the skin becomes red, changing to purple, especially noticeable in white-haired hogs. The hog is then usually within a very few days of death.
As already explained, not all cases are typical. Sometimes hogs die in an outbreak of cholera from undoubted hog cholera, and yet the ante mortem or post mortem symptoms show very little upon which to base a diagnosis. But we may easily demonstrate that these were cases of cholera by injecting their blood into susceptible hogs and by thus producing typical cholera.
A post mortem of a hog dying from cholera will show ulcers like those pictured here. Look for them in the large intestine.]