The Farmer's Veterinarian: A Practical Treatise on the Diseases of Farm Stock

by Charles William Burkett

—A fracture at the point of the hip. The most common cause is striking the point of the hip against a door post or pole. Sometimes a kick is responsible. While recovery follows, as a rule, from the very nature of the fracture, there is no treatment that will remedy the broken point. After the soreness has passed no inconvenience results; only a blemish is observed.

HOG CHOLERA.

—The term hog cholera has become quite ambiguous, partly on account of new discoveries concerning the cause of the disease and partly on account of what have been supposed to be two different but curiously related diseases being generally included under this general term. Until within a year or two we have supposed that there were two infectious diseases of hogs recognized under the general terms of hog cholera and swine plague. It now seems probable that we will be able to do away with the term swine plague entirely.

The disease considered here answers to the following requirements: (a) Infectious by association or other natural exposure; (b) the animal before death and the carcass after death show certain accepted symptoms which are clearly recognized as pertaining to cholera; (c) the blood is virulent and capable of reproducing the disease on inoculation into susceptible hogs; (d) attack and recovery confer immunity. It is to be understood that we might easily have diseases among swine where characteristic “a” or even “b” might be present and yet the disease be not true hog cholera.

AN ATTACK OF CHOLERA

One of the familiar attitudes assumed when the hog is affected with cholera. When this far along, not many cases of recovery are observed.

Until within recent years American authorities, bacteriologists and veterinarians alike, have very generally accepted a certain germ, the bacillus of Salmon and Smith, as the specific cause of hog cholera and another somewhat similar germ as the cause of what was supposed to be a distinct but curiously related disease—swine plague. But within a few years workers in the Federal bureau of animal industry have apparently demonstrated that hog cholera is caused by a living germ so small that it passes easily through germ filters which remove all known forms of the bacillus of Salmon and Smith.

It may be interesting to note further that this new germ is so small as to be invisible to the highest available powers of the best microscope. That it is a living organism and not a chemical poison may be very easily demonstrated. The curious relations to this disease of the old bacilli of hog cholera and of swine plague are not well understood, but it seems quite possible that they may play some part in the later development of the disease after the disease processes have been started by the invisible germ. While our old theories and supposed information concerning the cause of hog cholera have been very much disturbed by newer work, it is important to remember that hog cholera is now just as much as before to be recognized as a distinctly infectious disease. It is important to remember also that this infection is absolutely necessary, or there can be no cholera no matter how susceptible animals may be. There can be no cholera without this primary and specific cause any more than there can be plants in our wheat fields without the previous presence of mustard seed. Conditions of soil and climate may favor a rank growth of mustard. Conditions of feed and keep may favor the development and spread of hog cholera. They may decrease resistance and increase susceptibility, but cannot originally cause the disease. It is a rather common experience that hogs kept closely housed and fed, especially with such foods as corn, offer less resistance than do other hogs. In our vaccine work we frequently find hogs of this type which die readily under inoculation with blood of low grade virulence. Hogs of hardier type may become slightly sick or not sick at all with inoculation from the same infectious material. Pampered show herds appear especially susceptible to both natural infection and artificial inoculation.

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.