THE ERADICATION OF TUBERCULOSIS IN CATTLE.@

By A. D. MELVIN, D. V. S.,

Chief of the Bureau of Animal Industry.

INTRODUCTORY.

Notwithstanding the fact that much has been said upon the subject of the eradication of tuberculosis from our herds and much work has been done in that direction, this disease is, without doubt, upon the increase. The great agitation which has been going on for some time regarding meat and milk inspection has brought the question of tuberculosis before the public in a more direct manner than ever before, and it now occupies an important position in the minds of all reasoning people. Never, therefore, has the time seemed so favorable as at present for securing the indorsement and cooperation of the people in carrying out the work of eradication. In an important movement of this sort it is imperative that it be sustained by public sentiment, for without such indorsement those who are selfishly interested generally place so many obstacles in the way as to frustrate any effort in that direction. Without becoming alarmists to an unnecessary degree, it is the duty of the veterinary profession to keep this matter before the public in such a way that the public may become familiar with the subject and understand the importance of eradication from both an economic and health standpoint.

The very general impression throughout the medical profession until recent years that human tuberculosis was conveyed principally through the medium of dust and by inhalation failed to interest that profession in any movement looking toward the eradication of the disease from live stock. The various recent articles showing the ease with which this disease can apparently be conveyed from cattle to man, however, has awakened the interest of the medical profession, and it is now ready to support any reasonable movement looking to the eradication of the disease from meat and milk producing animals.

THE INCREASING PREVALENCE OF TUBERCULOSIS.

SOME MEAT-INSPECTION FIGURES.

The reports of the Bureau of Animal Industry indicate that tuberculosis among live stock is steadily increasing, as shown by the num

This paper was presented at the annual convention of the American Veterinary Medical Association, Kansas City, Mo., September 10-13, 1907.

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ber of animals found affected at the various slaughtering centers. The increase in the number of cases found is due in part, but only in part, to the increased efficiency of the method of inspection. For the fiscal year ending June 30, 1903, the percentage of tuberculosis found in cattle at abattoirs was 0.169; in 1904, 0.203; in 1905, 0.226; in 1906, 0.259, and in 1907, 0.363. For the months of January, February, and March, 1907, the percentage was 0.434, and for the months of April, May, and June, 1907, it was 0.539. Thus during a period of five years the increase in cases found upon post-mortem examination has been from 0.169 to 0.539 per cent, which surely is an alarming state of affairs.

Recent feeding experiments conducted by the Bureau have proved conclusively that hogs are readily infected through the ingestion of feces and milk from tuberculous cows. The percentage of all cases of tuberculosis of all the hogs slaughtered under Federal inspection for the fiscal year ending June 30, 1907, was 1.43. There is no doubt in the writer's mind that this percentage will be reduced to a negligible quantity as soon as the disease is eradicated from cattle.

CONDITIONS DISCLOSED BY THE TUBERCULIN TEST.

Considerable tuberculin testing of cattle has been done in Washington, D. C., and vicinity for the purpose of assisting the District authorities in obtaining a pure milk supply, and of obtaining for the Bureau further information regarding the extent of tuberculosis in that locality, and for other purposes. The tests made by the Bureau in 1907 showed about 17 per cent of the cattle reacting.

The percentage of tuberculosis in various States, shown by tests conducted by the officials of those States with Bureau tuberculin, indicate from 2.79 to 19.69 per cent of the cows reacting. It should be stated, however, that in all probability the majority of these tests were made in herds where the disease was thought to exist, and on that account the percentage may be higher than it would be if all the cows of a certain section were tested.

The recent agitation against the milk of tuberculous cows as human food has had the effect of causing many herds to be examined, with astonishing results not only to the owners but to the officials themselves. Can it be wondered at that so many infants and children die of intestinal tuberculosis when so many of the cows from which the milk is obtained are tuberculous?

THE IMPORTANCE OF ERADICATION AS AN ECONOMIC MEASURE.

Without considering the matter as a public health question, but looking at it entirely from an economic standpoint and as a business proposition, live-stock raisers can not afford to have tuberculosis in their herds. As an illustration, Argentina requires that all cattle

imported into that country shall be subjected to the tuberculin test upon arrival, and as a consequence exporters from the United States have had the test made on cattle intended for shipment. The results of these tests showed that in some of the purebred herds nearly 50 per cent of the animals were diseased, and in consequence many sales were lost.

When the practice becomes general for all buyers of breeding cattle to have animals tested before placing them in their herds the breeder of strictly healthy cattle will be much sought after. Already some breeders of purebred cattle have established or are arranging to establish such herds. As soon as breeders fully understand the fact that it is unprofitable to go on breeding cattle while tuberculosis exists in their herds much of the objection raised against the sale of live stock subject to inspection will disappear, for it would be worth the price of several condemned animals for the owner of a valuable herd to know the fact as early as possible if the disease exists in his herd, as the longer he delays in taking steps to prevent its spread the greater will be his loss eventually.

The recent effort of the large packing interests to buy all dairy cows subject to post-mortem inspection shows how serious the plague. is becoming. Sooner or later the man who raises tuberculous animals must suffer the loss, unless the loss is paid for out of public funds; and when the loss is placed upon the producer we may then know that the end of the disease is in sight.

Some years ago the Bureau of Animal Industry, in order to protect as far as possible American breeders of cattle from the danger of tuberculosis in imported stock, issued an order requiring all cattle imported for breeding purposes to be subjected to the tuberculin test. The wisdom of this step can be shown by merely stating that 19.7 per cent of the cattle tested since that time have reacted, and that from several foreign herds no cattle are even considered for testing on account of the general infection existing in those herds. Unless some steps are taken soon to eradicate the disease from our own herds, will not the same conditions exist in this country within a few years, if they do not already obtain in some instances?

THE RELIABILITY OF THE TUBERCULIN TEST.

There has been considerable incredulity with reference to the tuberculin test, particularly among those opposed to the movement to stamp out the disease, but the statements of such persons should not be given very serious consideration, except as they may be the means of prejudicing the uninformed against the tests. There is no more reliable diagnostic agent than properly prepared tuberculin in the hands of the careful observer. The reports received by the Bureau of Animal Industry from State officials from all parts of

the United States of tests made by competent veterinarians absolutely confirm this statement. Frequently affected animals give little or no reaction or a subnormal temperature, but in these cases any veterinarian of average ability should be able to diagnose the disease by physical examination alone, as in nearly all such cases the disease has become so generalized that a mistake should not be possible. It is understood, of course, that tuberculin should be administered by a reliable veterinarian and that in addition to the test a physical examination should be made of the cattle.

That impotent tuberculin has been on the market is a fact which has been demonstrated by the Bureau, and at its request Congress gave to it authority to make tests of tuberculin, vaccines, and similar products found on the markets, and to publish results. Such tests are now being made, and if any inferior agents are found public notice of that fact will be given. The use of worthless tuberculin may to some degree have been the means of prejudicing some veterinary practitioners, as well as other persons, against the use of any tuberculin.

SOME MEASURES FOR THE ERADICATION OF TUBERCULOSIS.

METHODS USED IN DAIRY HERDS.

In various sections where an effort has been made to secure a wholesome milk supply many dairymen have been found ready of their own accord to assist in the work of eradication. Many others would do so with some small financial assistance. Another class, however, would have to be forced to submit their cattle for examination. As the eradication of the disease in such cases is undertaken as a public health measure, it would seem reasonable that the States should assist in recompensing, at least in part, the dairymen whose cattle are slaughtered. Many of these dairies consist of highly bred cattle, and in such cases it is often found advisable to employ the Bang method of segregating the reacting animals and using them for breeding purposes under certain precautions rather than to slaughter them.

The following is a form of agreement prepared by the Bureau of Animal Industry and required as the consideration for testing a herd:

[United States Department of Agriculture, Bureau of Animal Industry.]

AGREEMENT.

In consideration of the testing of my herd of cattle by the Bureau of Animal Industry of the United States Department of Agriculture and the assistance of said Bureau in enabling me to produce and maintain a herd of cattle free from the contamination of tuberculosis, I [name of owner], of [post-office address],

owner of said herd of cattle, comprising [number and kinds over 6 months old; number and kinds under 6 months old], do hereby agree as follows:

1. I will cause all animals which react to the tuberculin test, and which also show other marked symptoms of tuberculosis, to be slaughtered within a reasonable time under the United States meat-inspection regulations, and I will cause the carcasses of said animals to be disposed of according to the meatinspection regulations of the Bureau of Animal Industry, based upon the lesions found upon inspection.

2. I will cause all animals which react to the tuberculin test, but, which show no other evidence of tuberculosis, either to be slaughtered and disposed of as herein provided for animals which show also other evidence of tuberculosis, or I will cause such animals to be removed from the herd and portion of the farm upon which the healthy animals of the herd are maintained, and I will cause the diseased animals to be segregated from the healthy animals, and thereafter they shall remain so segregated.

3. In all cases where the milk from such segregated reacting cows is to be used for any purpose whatever I will cause the said milk to be sterilized.

4. Segregated reacting bulls may be used for breeding, provided they are held on leash and are not permitted to leave the premises reserved for their use, and provided the healthy cows bred to such bulls are not unduly exposed to infected premises or to other diseased cattle.

5. I will cause the young from segregated reacting animals to be removed from their mothers at birth, and will not permit the said young to suck their mothers.

6. Any part of my premises contaminated by reacting animals will be submitted by me to a thorough disinfection under the direction or supervision of the Bureau of Animal Industry.

7. All cattle owned by me, both healthy and tuberculous, I will mark, or allow to be marked, in such manner as to enable their identity to be retained, and I will not change the location of or slaughter any tuberculous cattle except after due and timely notification to the Bureau of Animal Industry, stating the exact nature of the change of location, or the exact date, name, and address of the official establishment at which the animal or animals are to be slaughtered.

8. I will add no cattle to the said herd which have not passed a tuberculin test administered by an authorized public agent qualified to perform such test or by an inspector of the Bureau of Animal Industry.

9. I will comply with all reasonable sanitary measures which are indicated by the proper officials of the State or Territory wherein my herd is located, or by the local board of health under whose permit I am disposing of dairy products, or by the Bureau of Animal Industry.

In witness whereof I have signed this agreement this one thousand nine hundred and

day of

Witness:

(Address)

Owner of the

herd.

TRACING ORIGIN OF ANIMALS FOUND DISEASED IN MEAT INSPECTION.

This Bureau has recently undertaken to ascertain the origin of all tuberculous cattle slaughtered at establishments where the Federal