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.
THE RESULT OF HOG CHOLERA
A post mortem of a hog dying from cholera will show ulcers like those pictured here. Look for them in the large intestine.
At the autopsy of an ordinary case of cholera the first and perhaps the most striking thing seen is the purpling of the skin. On opening the carcass small blood spots may be found under the skin and in the fat cut through. The glands along the intestines are intensely inflamed. The mucous membrane of the stomach is frequently thickened and roughened and in chronic cases there may be ulcers. On opening the intestines we see areas here and there of intense inflammation in the acute cases or numerous ulcers in cases of more chronic type. In very acute cases we find areas intensely inflamed, even bloody in places. The slow chronic cases develop characteristic hog cholera ulcers. These may appear at almost any point on the lining membrane, but more particularly in the blind pouch and around the point where the small intestine connects with the large intestine. On stripping off a very thin transparent membrane covering the kidneys, a typical case of hog cholera will usually show minute red spots on the surface somewhat resembling the covering of a turkey egg, which gives the common name of turkey egg kidney of hog cholera.
Preventing the Disease.
—Clearly there are certain things which the owner of healthy hogs in a hog cholera district should do and a good many things which he should not do. The same is equally true for the man who has sick hogs in a neighborhood where there are uninfected herds. The owner of healthy hogs and his family should keep away from public stock yards, from all pens and yards on other farms whether sickness among hogs prevails or not. It may easily occur that a neighbor’s hogs may appear well but have recently received the infection and be already capable of scattering the disease. We do not know at what period in the development of this disease infected hogs become capable of disseminating hog cholera.
During a hog cholera season the owner of healthy hogs should institute something in the way of private quarantine and pleasantly, perhaps, but firmly, ask visitors, especially stock buyers and threshing machine crews, to keep at a reasonable distance from the pens and yards. It is safer for one man to have exclusive care of healthy hogs during the hog cholera season, and this man should be very careful where he goes with reference to possible infection. Special fencing or other provisions should be made wherever practical to keep dogs out of the pens and yards, for, under certain conditions, dogs become very active agents in spreading the disease.