Prevention and treatment.—The prevention of pleuropneumonia, as of other contagious diseases, consists in keeping animals so that they will not be exposed to the contagion. As the disease arises only by contagion, there is no possibility of an animal becoming affected with it unless it has been exposed. If, therefore, pleuropneumonia exists in a locality the owner of healthy cattle should make every effort to keep his animals from coming near affected ones or which have been exposed. He should be equally particular not to allow persons who have been on the infected premises to visit his own pastures, stables, or cattle.
If pleuropneumonia breaks out in a herd, every animal in it should be slaughtered, the stables thoroughly cleaned and disinfected, and no other cattle allowed on the premises until a period of 90 days has elapsed.
Medical treatment of affected animals is unavailing and should not be attempted. No matter how valuable the diseased animals may have been before they contracted the disease, they should at once be destroyed and the contagion eradicated. This is the best policy for the individual as well as for the community.
The eradication of this disease by local or National Governments can be successful only when the same principles are adopted and carried out as here recommended for individual stables. It is then a difficult undertaking, simply because the contagion is generally widely disseminated before any measures are adopted, and because a great majority of cattle owners will never report the existence of the disease. Regulations must therefore be enforced which will insure the prompt discovery of every herd in which the disease appears, as well as the destruction of all diseased and exposed animals and the thorough disinfection of the premises.
To discover pleuropneumonia sufficiently early for this purpose, the district supposed to be infected should be clearly defined and inspectors should be constantly employed to inspect every herd in it at least once in two weeks, or, better, once a week. No bovine animal should be allowed to go out of the defined district alive, and all which enter it should be carefully inspected to insure their freedom from disease. As an assistance to the discovery of diseased herds, every animal which, from any cause, dies in the infected district and every animal which is slaughtered, even if apparently in good health, should be the subject of a careful post-mortem examination. Many affected herds will be found in this way.
In addition to these measures it is also necessary to guard against the removal of animals from one stable to another and the mixing of herds upon common pastures or in the public highways. The object must be to isolate every individual's cattle as completely as possible, or otherwise a single affected animal may infect a dozen or more herds. To prevent surreptitious sale or trading of cattle, each animal must in some way be numbered and recorded in the books kept by the official in charge of the district. In the work of the United States Department of Agriculture a numbered metal tag was fastened to each animal's ear and index books were so arranged that with a number given the owner could be at once ascertained, or from the owner's name the cattle for which he was responsible could be at once learned. In this way, if an animal was missing from a stable, the fact became apparent at once, or if one too many was found in a stable the number in its ear would indicate where it came from.
When pleuropneumonia is discovered by these means, the entire herd should be slaughtered as soon as the formalities of appraisement can be arranged. In country districts the carcasses should be buried, as it is generally impracticable to dispose of them in any other way. In city districts the animals may be taken to a slaughterhouse, with such precautions as are possible to prevent dissemination of the contagion. The animals should be slaughtered under the supervision of an inspector. The healthy carcasses may be utilized for food, but the blood, entrails, and all diseased carcasses should be heated to a temperature equal to that of boiling water or above, and then used for the manufacture of fertilizers.
The disinfection of premises should be thorough and should be carried out by a trained corps of men employed for the purpose. The floors of stables should be removed, the accumulations removed from beneath them, the contents of haylofts should be destroyed, and the woodwork and soil beneath the stables should be thoroughly drenched with a solution of bichlorid of mercury, 1 part to 2,000 of water. After the flooring is replaced the woodwork should be coated with limewash, containing one-fourth pound of chlorid of lime to the gallon of mixture.
Usually in these cases the owners are dependent upon their herd of cows for a living, and consequently it is difficult or impossible to hold the stables vacant for any considerable period. In a majority of instances cattle may be admitted at once to stables so disinfected, without the reappearance of the disease. Occasionally, however, it will reappear without apparent cause. For this reason the inspection and other measures must be maintained in the infected district for six months or a year after the last case of disease has been disposed of.
Many people have objected to the slaughter of diseased and exposed animals as an unscientific and expensive method of eradicating the disease. To these it may be answered that it is the only method which has ever proved successful, and that in the end it is much more economical than temporizing measures.