EXTINCTION OF TUBERCULOSIS IN CATTLE.
As cattle are the great propagators of tuberculosis on the farm, the question of extinction necessarily centres around this race. As in all other dangerous infections, the most prompt and successful method would be in the time honored one of destroying the infected and thoroughly disinfecting all their products. The only barrier to success in such a case would be the conveyance of infection anew from man to cattle after the herd had been purified. The demonstration that cattle are less susceptible to infection by the human sputa than many had supposed does away largely with this objection, as in a generally purified bovine race, the few primary cases contracted from man could be easily taken care of. Then, if tuberculous persons were interdicted from attendance on cattle, the danger in this direction would become very nearly a negligible quantity.
There remains the question of expense and many honestly consider this as absolutely prohibitory. The estimate of 5 per cent. of our 68,000,000 head to be killed and paid for at $25 per head, would be $85,000,000. But there is no necessity for this. Our fat steers at the packing houses are tuberculous only to the extent of 0.02 per cent., speaking well for their dams and nurses. The estimate of 5 per cent., based upon the testing of those few herds that have been taken because they were already known to be tuberculous, is unquestionably far above the actual ratio for the United States. It may apply to dairy cattle in some infected districts, but, for the bovine race of the whole country, it is absurdly high. If we had 10, 20 or 50 per cent. infected, as in some countries of Europe, the objection of expense might be a formidable one, but when the ratio of the infected is but 2:10000, we have every encouragement on the score of expense to enter on a campaign of extinction. But again, we do not need to deal with 68,000,000 cattle as we can omit the steers which are so little affected and which will all come to the slaughter house in two or three years. The source of their infection (a few cases excepted) is in the older cows and bulls of the dairy and breeding herds, and this brings down our total to a little over 17,000,000. The average census price for dairy cows is $29 and, as the condemned cows are depreciated by their condition, it would be a high average to estimate them at $20. Again, the average infected ratio of cows for the entire country would be set high at 2 per cent., and on this basis it might well be that the required indemnity would not aggregate much over $6,000,000. Five or even ten times that amount would be a mere trifle in comparison with the $3,000,000,000 value, constantly encreasing, of our domestic animals, with the $99,210,272, representing our yearly product of beef and beef products, with our annual dairy products, worth $500,000,000, (Alford), or with our yearly loss of 100,000 of our population in the very prime of life when they are of the greatest value to the country, representing a yearly drain of $100,000,000, beside all the suffering and loss entailed by their prolonged and too often helpless idleness. Though this last item is doomed to continue for a length of time after the disease has been extinguished in our herds, it is receiving constant accessions from the latter, and can never be entirely done away with until our cattle are above suspicion.
An even more serious problem is the demand for tuberculin and above all for accomplished, experienced and honorable veterinarians fitted to conduct the sanitary campaign over the entire country. The tuberculin cannot be produced in a week or a month, yet the problem of its production in any required amount in a few months is merely one of the encrease of existing plants under the management of the same careful hands now engaged upon it. As to veterinarians it would be impossible to secure at once the required staff of men capable of carrying out the work over the whole country. But this is not essential. The work can be begun in the counties supplying the large cities with milk, and in the great butter and cheese producing areas where it is so urgently needed, and it must be made to include all thoroughbred herds, which are so constantly drawn upon to improve the blood elsewhere, and each herd, county and district, as freed from infection must be scheduled and no additions made to it from outside, except under the guarantee of the tuberculin test, repeated in six months. The reacting animals, must be appraised, excluded from the herd, and disposed of, it may be to the butcher to be killed under official expert inspection, and the salvage, if any, to be deducted from the appraised value; or to be rendered and the salvage estimated; or to be buried as the case may be. In all such cases the other animals (horses, pigs) that occupy the same buildings and yards should be tested, although the risk of the infection of cattle from these animals is comparatively small. Unless in badly infected herds, steers and young cattle, which can be kept in a separate herd need not be tested. Vermin must be killed. Thorough disinfection must be applied to buildings and yards, and the dairy herd must be retested at the end of every six months until no more reactions are met with.
In this way the campaign in any State can be begun with a small staff, which may be steadily encreased as men are trained to the work, and in no great length of time the dairying and breeding herds can be purified and the investigation carried into the more purely agricultural fields, where herds are small and usually free from infection. Many minor points would require the attention of a competent superintendent of the work. My object here is to make a plea for the approved and attested method which has never failed in the case of other animal infections on enclosed farms, and which is based on the absolute destruction of every seed of the disease in the area under sanitary control. The method has the apparent drawback, that it demands a greater relative outlay at the start, than do others proposed, but in view of its certainty, and the confident hope of an early abolition of all infection, loss, and expensive expert control, it must, in my opinion, be looked upon here, as it has always proved in the past, the course of the truest economy. It may be compared to the treatment of a field of thistles by removing the offensive weeds, root and branch, before they have advanced to seed, instead of merely cutting them down with a mower, and leaving the roots, to grow anew, to leaf, to blossom and seed, in spite of the temporary partial drawback. But as the prospect of early legislation along this line is not a bright one, the expert must accommodate his aims and efforts to what can be done under the existing laws.
Breeding Healthy Stock from Parents with Latent Tuberculosis. When a State is not pledged to exterminate tuberculosis by prompt and radical measures, it is quite possible to raise healthy stock from sires and dams that have the disease in a latent form. It is very exceptional that calves are born tuberculous. If, then, they are kept in a pure environment and furnished with the milk of sound nurses, or even with the milk of their own tuberculous dams, after it has been heated for one-quarter of an hour to 180° F. or 212° F. they can be preserved in perfect health.
This is especially adapted to herds of valuable thoroughbreds, the destruction of which would be a serious loss, and the preservation of the strain of blood a most desirable object.
The whole herd should be tested with tuberculin, and the advanced and generalized cases, that can be detected by objective symptoms, should be at once destroyed and safely disposed of. The animals in good condition and that have not reacted should be placed in a new barn and yard, or where no tubercle has been, or in places that have been thoroughly disinfected, under special attendants. There will remain the animals in good condition with no objective symptom, but that have reacted, and these are placed in separate barn, yard and pasture well away from other stock, under their own attendants, for breeding purposes. They should have the best of food and air, clean, well lighted, roomy buildings with shelter from storms, clean sheltered yards, and in summer, pasturage. Any cow showing indication of active advance or generalization of the disease (cough, wheezing, dyspnœa under exertion, excessive pallor of mucosæ, unthriftiness) should be at once separated and destroyed as endangering the reinfection of others, and the stable subjected to disinfection. The calf, as soon as born, must be removed to a special building or park, where it shall get milk from a sound cow or that of its own dam after it has been carefully sterilized. After sterilization the milk cannot safely be returned to the unscalded pail into which it was drawn from the cow, and it should be fed by separate attendants who have not milked nor handled the affected animal. Any loss of condition, unthriftiness, cough or scouring on the part of any of the calves should be the signal for its separation from its fellows, subjection to the tuberculin test, and, if it reacts, for its destruction and the disinfection of the building where it was. It is well to test each calf at six weeks old and to remove the reacting ones. The success of this method is now well established.
Goodman, of Dorpat, applied it largely as early as 1891, rearing the healthy calves of reacting cows on the milk of cows that had stood the test. Bang, of Denmark, raised such calves to sound maturity on sterilized milk. Reynolds, of Minnesota, reports the raising of twenty-four healthy calves from infected cows on the milk of tested cows, while three fed on milk of reacting cows, which was supposed to be sterilized, all became tuberculous. McEachran (1899) in an extended experiment succeeded perfectly with the milk of tested cows only. I have now in hand a Jersey herd in which the progeny, fed on the milk of their reacting dams, became tuberculous without exception, and in the years following, those fed on the milk of the same reacting cows after it had been kept at 180° F. for half an hour all grew up healthy.
Under this method, inasmuch as the infection is not at once extinguished, but temporized with for the benefit of the stock owner, State indemnities are not necessarily called for. Yet the State can profitably test the cattle at public expense, mark indelibly those that react, schedule them and control them, so that they will not be allowed to change hands nor to mingle with sound animals until finally butchered, dead or recovered. The State should see to the thoroughness of the seclusion, disinfection, the safe disposal of all products from milk to manure, and the testing at intervals of three or six months of both cows and calves.
Raising Healthy Offspring Without Sterilizing the Milk. In the northwest territories cows and heifers that have reacted to tuberculin, but which otherwise appear to be in good health, are made into a herd by themselves and placed on a special range apart from all other cattle. They live in the open air, slight shelter being allowed in winter only, and their calves are allowed to suck the dams until winter. The wide range, the open air life, and the early destruction by oxygen and sunshine of the discharged bacilli, tend in the main to ward off infection, except such as comes in the milk, and the majority of the calves grow up in apparent health and are fattened for market. A small minority are born tuberculous or contract the infection from the milk, but this does not seriously impair the financial success, and living in the open air they bring little danger to others. The loss is infinitesimal as compared with the expense of milking a large herd, sterilizing the milk and feeding it by hand. Advanced cases, with objective symptoms, should always be removed, and the cows may be tested at intervals if compatible with profit. The seclusion of the herd should be complete, by distance, by the configuration of the country, or by fence.
For this system the climate of our Southern States, where stock can remain out of doors all the year, offers a better field than the semi-arctic northwest.
Removal of all Unthrifty Animals and Those Showing Physical Symptoms of Tuberculosis. Before the days of tuberculin testing I succeeded in extinguishing tuberculosis in several herds by the prompt removal of all unthrifty animals and such as showed objective symptoms of tuberculosis, the disinfection of the buildings, the restocking from sound herds, and the strict separation of the new stock from the old. In one herd of 200 this entailed the final destruction of the whole original herd; in others the destruction was in the main limited to particular (susceptible) families. But in these days, with the tuberculin test available, a resort to a method of this kind would produce an unnecessarily slow, uncertain and expensive result.
Removal of Animals Showing Objective Symptoms or Reaction under Tuberculin. The Bang (Danish) method is the chief example of this, and is so considerate of both state outlay and stock owner’s interests that it is deserving of high praise. Under it the State usually waits for the stock owner to take the initiative, but to encourage applications from the owners, it furnishes tuberculin testing without expense, and even allows a small indemnity for animals killed because of advanced tuberculosis. In return for this the stock owner agrees to furnish separate buildings (or enclosures), yards and pasturages, new or, when necessary, disinfected, one set for the high conditioned, nonreacting, healthy herd, and a second for the animals that reacted but which show no further sign of tuberculosis, with separate attendants, utensils and other appointments for each. This reacting herd is furnished with the best of food, air, accommodation and hygiene generally, and the milk is sterilized before it is allowed to pass into consumption by man or for calves or pigs or for the production of butter. The quarantined herd is marked, registered, and kept under government surveillance; it cannot be parted with for stock uses, but it is at the disposal of the owner to keep it for milk, or fatten at once for the butcher. Finally every member of this herd is slaughtered under government inspection, and the beef put on the market or sent to the rendering works as may be decided. The system secures the hearty coöperation of dairyman, dealer and government, and while it comes short of the speed and efficiency of a generally applied method of extinction, it is accomplishing a great work for Denmark, putting an immediate stop to the advance of the disease in the worst infected herds, and placing the latent cases of such herds in a safe seclusion for the rest of their lives. At first the tested herds showed 40 per cent. affected; now less than 20 per cent.
The feature which would be likely to work the least satisfactorily in the United States, is the disposal of the sterilized milk as such. It is to be feared that this milk would find but a poor market with us, and if it proved unsalable, the preservation of the reacting herd would be no longer an economic success.
In Pennsylvania where practically the same method is in force, leaving it in the option of the owner to keep the reacting latent cases and sterilize their milk, or to abandon them to the State, have them appraised and slaughtered with indemnity, the uniform practice has been to accept the latter alternative. Not a single owner, I believe, has elected to keep a herd in quarantine and sell the milk sterilized. The result has been that four times the number of applications come in that the appropriation will warrant the officials to take in hand.
A special feature of the Pennsylvania method is the provision that a stockowner can have his herd examined, and tested with tuberculin, at his expense, the State to furnish a certificate setting forth the condition of the animals. In case of infection, the owner has the option of abandoning the reacting ones to the State, to be secluded, or appraised and slaughtered, he meanwhile guaranteeing that he shall introduce no new animals into the herd except by tuberculin test under the direction of the State Board.
The usual provision is in force that no indemnity is allowed for any animal that entered the state not more than three months before, and without the tuberculin test demanded of all such stock animals.
Indemnities are restricted to $25 per head and under for non-registered animals and grades, and $50 for registered thoroughbreds. The average appraised price has been $23.
On the whole an excellent work is being done in Pennsylvania, and herds now tested are found to contain not more than half as many infected animals as did those tested a few years ago. A better showing would doubtless have been made if the State appropriation had permitted the board to give attention to all applications made.
The good results may be attributed to the adoption of a system which secured the confidence and trust of the stockowner: he sees that the State has no desire to oppress nor injure him; he is in no dread of a high-handed confiscation of his remunerative property without indemnity; while advanced cases are destroyed he is left the option of segregating his latent cases and marketing their products under the precaution of sterilization; he can raise the progeny of these animals if he will, under similar precautions; he can sell his stock and its product under government certificate if they prove sound; he can avail of government assistance in protecting his herd against reinfection, by the testing of animals to be purchased. Under such a system there is no object in secreting infection, and in underhanded sale of tuberculous animals, with the spread of the disease into new centres. Even the tardy or inimical stockowner is roused to action by public opinion, when he finds the market for his suspected product growing more and more uncertain, and feels the daily encreasing pressure of opinion among neighboring owners, that he is exceeding his rights in maintaining an infected herd in the very midst of their purified ones.
A most important item of the system of Pennsylvania, and of sixteen other states, is the compulsory testing of all stock cattle introduced into the State. This has the further support of the Federal Government which demands a tuberculin test of every stock bovine animal imported into the United States. This is a natural corollary of every attempt to restrict or extirpate tuberculosis from a State, but when through willful blindness a great State like New York, repudiates a measure of this kind, it but makes its dairy and breeding herds the depository of the reacting animals that other states wisely exclude. The sifting process goes on at Buffalo and other centres and the New York herds are loaded with the rejected, diseased animals. Under the operation of this, and the denial of indemnity for animals slaughtered, it will be wonderful, if the New York stock owner is not soon roused up from his idle dream of fancied security, by a great extension of the infection.
Generally Applicable Measures. Under any system many special rules will be demanded in individual cases, which it will require the skill of the expert sanitarian to apply, and which cannot be referred to here. The following are generally applicable whether by the owner in his particular herd, or by the State or other authority dealing with the subject.
1st. On discovery of a case of tuberculosis, test the whole herd with tuberculin. (See Tuberculin Testing.)
2d. Remove all animals that show a typical reaction.
3d. Destroy and burn, boil or deeply bury all cases of the disease, unless it is decided to form an isolated herd of latent cases which are in good condition and apparent good health.
4th. In case of doubt or disturbing influence which may have caused rise of temperature (calving, heat, exposure, concurrent disease, changes in management, etc.), keep the suspected animal apart for four weeks and test again.
5th. Repeat the test every six months, and if two successive tests show no indication of tuberculosis, the herd may be accounted sound.
6th. As soon as tuberculous animals have been removed from a stable, let it be vacated and thoroughly disinfected with chloride of lime, 4 ozs. to 1 gallon of water, and enough quick lime to make a good whitewash which will show if even a square inch is missed. When chloride of lime is objectionable because of its tainting the milk, use mercuric chloride 1 dr. to 1 gallon water, with enough sal ammoniac to make it freely soluble. The roof, walls, and especially the floor, gutter and feeding trough must be first thoroughly scraped, washed and cleaned, all rotten wood work must be removed, and, in case of double boarded walls, the boards must be removed on one side to permit of a thorough application. Utensils should be scalded and dressed with carbolic acid, 1:20. A stable incapable of disinfection should be abandoned for a length of time or burned.
7th. In making new purchases, avoid any herd in which tuberculosis has appeared, or that has had sickness or deaths in recent years.
8th. Do not purchase from city, suburban nor swill stables.
9th. Do not take a cow that is in ill health or low condition, especially one with cough, nasal discharge, foul breath, wheezing breathing, hard nodules under the skin, diseased udder, swollen bones or joints, or a tendency to scour or bloat.
10th. Test every animal with tuberculin before admitting it into the herd.
11th. Do not admit strange cattle to house, field or yard. Keep apart from the herd until tested.
12th. Keep each animal strictly to its own stall and manger.
13th. Board up between the stalls in front so that no two cows can feed from the same manger.
14th. Be especially watchful of the older cows and on the slightest sign of ill health, separate and subject to the tuberculin test.
15th. In case a herd of cattle is found to be tuberculous, subject to the tuberculin test all domestic animals that have mingled with them freely and fed from the same troughs. Remove those that show a reaction.
16th. Exterminate the vermin (rats, mice, sparrows) in a building where tuberculosis has prevailed.
17th. Let no consumptive person attend on cattle nor prepare their food.