TUBERCULOSIS-FREE ACCREDITED HERDS OF CATTLE.

A good beginning has been made in the establishment of a list of herds of pure-bred cattle officially accredited as being free from tuberculosis. A statement of methods and rules was adopted by the United States Live Stock Sanitary Association and by representatives of pure-bred cattle breeders' associations in December, 1917, and was approved by the Chief of the Bureau of Animal Industry. The plan, in brief, is to test the cattle with tuberculin at the request of the owner, to eliminate any reacting animals either by slaughter or by following prescribed sanitary measures, to repeat the test at prescribed intervals, and to list as tuberculosis-free accredited herds all herds entitled to that distinction. Official certificates are issued to the owners of such herds. A list of accredited herds and of herds that had successfully passed one test with a view to certification, comprising herds tested up to the end of the fiscal year, has been printed and a summary is given in the following table. An "accredited" herd is one that has successfully passed two annual or three semiannual tests. The herds "tested once without reactors" must pass subsequent tests before being accredited and certified. The work shown in the following table forms a part of that composing the preceding table.

Summary of herds of cattle officially accredited as free from tuberculosis and of herds that have passed one test with a view to later certification.

LIVE-STOCK SANITARY WORK IN INTERSTATE COMMERCE,

In the course of the inspection and quarantine service to prevent the spread of animal diseases through interstate commerce there were inspected at market centers 20,987,998 cattle, of which 52,092 were dipped under bureau supervision in order that they might continue in interstate transit. Sheep to the number of 17,019,386 were inspected. at stockyard centers for scabies and other contagious diseases, and 651,339 were dipped under bureau supervision in order that they might be disposed of for purposes other than immediate slaughter.

Swine to the number of 254,731 were inspected and under the bureau's supervision were given the immunization treatment against hog cholera for interstate shipment from public stockyards.

Bureau stations reported 23,441 cars as arriving at points where inspection is maintained, carrying animals affected with a contagious, infectious, or communicable disease. During the year 42,069 cars were cleaned and disinfected under bureau supervision on account of bureau regulations or on request of Canadian government officials, State officials, and transportation companies.

There were inspected by bureau veterinarians, in compliance with the laws of the States to which the animals were destined, and upon request of transportation companies or cattle owners, 84,400 cattle moving interstate for purposes other than immediate slaughter, of which 26,667 were tested with tuberculin. Of the number tested 745 reacted, indicating that they were affected with tuberculosis, and 54 showed temperatures which required them to be held as suspects for further examination.

There were also inspected by bureau veterinarians, in compliance with the laws of the States to which the animals were destined, and upon request of transportation companies or shippers, 25,798 horses and mules, 10,228 of which were tested with mallein, 1 showing typical reactions to the test, and 2 were held for further examination.

VIOLATIONS OF LIVE-STOCK TRANSPORTATION AND QUARANTINE LAWS.

The bureau has continued to report to the Solicitor of the department, for presentation to the Attorney General for prosecution, cases of apparent violations of live-stock transportation and quarantine laws. Many of these cases have required special investigation on the part of bureau employees, such as interviewing witnesses and examining railroad and other records for the completion of evidence. Six bureau employees were regularly assigned to this work, though the greater part of the work of collecting evidence and preparing and submitting reports is done by bureau employees at stockyard centers, in connection with their other duties. The enforcement of the so-called 28-hour law has resulted in better facilities being provided for the feeding, watering, and handling of live stock in transit.

TRANSFER OF WORK.

The supervision of the interstate transportation of live stock and the work relating to the enforcement of the 28-hour law have been transferred to the Field Inspection Division, effective July 1,

1918.

PATHOLOGICAL DIVISION.

The Pathological Division, which was supervised by John R. Mohler in addition to his duties as assistant chief of the bureau up to December 10, 1917, and of which John S. Buckley has since been acting chief, has been engaged mainly, as heretofore, in the scientific investigation of diseases of animals and in assisting in the control of viruses, serums, and other remedies used in the treatment of live stock. Special cooperation with the War Department in dealing with diseases of horses and mules was a feature of the year's work.

GLANDERS INVESTIGATIONS.

In connection with cooperative work with State authorities for the control of glanders of horses and mules the complement-fixation test was applied to 1,411 samples of serums, 251, or 17.8 per cent, of which gave positive reactions to the test.

Cooperative work was done with the War Department in the control and eradication of glanders among Army horses and mules. The complement-fixation test was applied to 800 samples of serum from horses and mules at various remount depots and cantonments throughout the country. These samples were largely from animals giving an indefinite reaction to the ophthalmic mallein test, or were sent in for a confirmation of positive findings with the allergic tests, and also in cases in which every possible precaution to exclude glanders infection was to be used. Stock solutions of glanders antigen for the complement-fixation test were furnished to various Army laboratories, together with details of the technic of the test as conducted by the bureau.

Limited tests, on glanderous mules, of a mallein prepared from strains of Bacillus mallei isolated from lesions in mules did not show this mallein to be any more specific than mallein made from strains of the organism from horses.

DOURINE.

The complement-fixation test has continued to be extensively employed for the diagnosis of dourine of horses, 45,651 samples of serum having been tested, 1,018, or 2.23 per cent, of which gave positive reactions to the test.

A second multiple pipette has been devised for handling serum samples, whereby large numbers of samples can be tested easily in the daily routine with less help than in previous years. An improved method in the preparation of the dourine antigen by the use of distilled water to eliminate the red blood cells in collecting the trypanosomes has been found very satisfactory.

Cooperative work was done with the War Department in the testing for dourine of a number of samples of serum from mares which were to be used for breeding purposes to insure their being free from this disease.

ABORTION DISEASE.

Efforts to acquire more definite information regarding infectious abortion of cattle have been continued, the procuring of further evidence as to how the disease is disseminated, and the possibilities of immunization as a means of control having received particular attention. Numerous methods of obtaining information have been employed, namely, (1) the utilization of cattle in experiments where the environment could be controlled, (2) the observation of infected herds where the disease has existed for a variable length of time, and (3) the bacteriological and histological study of the tissues of suspected animals obtained from abattoirs.

By making repeated serological tests of numerous herds, both where the infection was of recent origin and where it was known to have existed for several years, a marked difference has been noted in the rapidity with which the disease spreads, even though the herds

have been maintained under very similar conditions. Additional evidence has been obtained that susceptible pregnant heifers may readily acquire the disease through the ingestion of comparatively small amounts of infected material, and that nonpregnant cows as a result of ingesting the infection may develop positive serum reactions and eliminate abortion bacteria in their milk.

While experimental work thus far conducted has failed to incriminate the bull as an actual disseminator of the disease at time of service, bacteriological examinations of the generative organs of 33 male animals, the blood serum of which showed some agglutinating properties for abortion bacteria, yielded positive results in three instances. There are grounds for suspecting that bulls of this character may be capable of contaminating their environment with abortion infection and in this manner at least be menacing factors as disseminators of the disease.

Immunization experiments with vaccines on animals where the exposure has been controlled, and also under herd conditions, have been in progress for some time, but the work has not advanced sufficiently to justify drawing any definite conclusions.

Serological tests applied at regular and frequent intervals to the blood serum of pregnant heifers to which had been administered by the mouth a sufficient quantity of abortion-infected material to cause them to abort later has demonstrated that a wide variation exists in the period of time that intervenes before agglutinins or complement-fixing bodies are elaborated. The negative period following the administration of the infection in seven cases, all of which subsequently aborted, varied from three weeks to four and one-half months. The fact that animals give negative serum reactions at the time of removal from infected herds need not, therefore, necessarily imply that they are not harboring the abortion organism, and that they may not develop positive serum reactions and abort at a considerably later period.

EXAMINATIONS FOR TUBERCULOSIS.

Specimen tissues from 86 cattle that had reacted to the tuberculin test, but in which no visible tuberculous growths had been found on post-mortem examination, were referred to the pathological laboratory for decision as to the presence of tuberculous lesions. By means of microscopic examination or animal inoculations, or both, the presence of tubercle bacilli was demonstrated in 63 of the samples, while 23 gave negative results.

A specimen of unusual interest, found during the regular course of meat inspection, consisting of the lungs from a cow bearing lesions similar to those of tuberculosis, yielded an organism which is evidently one of the pseudotubercle bacilli and which is being studied.

OIDIOMYCOSIS IN CATTLE.

Experimental work on coccidioidal granuloma (oidiomycosis) has been completed, and from the data obtained the following conclusions have been drawn: The affection has been observed in cattle as a natural infection of the bronchial and mediastinal lymph glands. It is transmissible experimentally to guinea pigs, rabbits, dogs, cattle, sheep, and swine. Cattle affected with the disease show no

response to subcutaneous allergic tests. Neither specific complement-fixing bodies nor agglutinins can be detected in the sera of affected animals. A paper reporting this work has been prepared for publication in the Journal of Agricultural Research.

DISEASE OF EYES OF CATTLE.

A disease of the eyes of cattle appeared in the summer of 1917 on a farm in Maryland. The history of the outbreak showed that after the first few animals had been affected for a short time the disease spread rapidly, or within two days, to other lots of cattle, some of which were at a distance from the ones first attacked.

The disease was characterized by a profuse flow of tears, followed by cloudiness of the cornea and the development of ulcers upon the surface of the cornea. In the progress of the disease the cornea became opaque, and in the worst cases the whole eye seemed involved, resulting in total blindness in one or both eyes.

Many attempts to isolate a pathogenic organism from the eyes of the affected cattle were made, but without success. It was found to be impossible to transmit the disease to healthy cattle or to laboratory animals by means of inoculating them with any of the bacteria recovered from the diseased eyes.

In treating the affected eyes the best results were obtained from a 1 per cent solution of silver nitrate applied to the eye gently with a soft cotton swab every second day until there was noticeable improvement and every fourth or fifth day thereafter until the eye became clear or free from the inflammation.

INFLAMMATION OF THE JOINTS IN SWINE.

Enlarged and inflamed joints (arthritis) of swine have been found often in the course of meat-inspection observations, and when the diseased joints are those of the hams or shoulders the loss in meat food. products becomes of some importance. Investigations of the condition have therefore been made.

A large percentage of the joints examined contained a small Grampositive red-shaped organism which resembles Bacillus pyogenes in morphology but differs from it in a few cultural characteristics. Results of experiments indicate that this unidentified organism is a causative factor of the arthritis. A pig inoculated intravenously with a pure culture of the organism on two occasions developed arthritis with distention of the synovial capsule, a condition typical of the early stages of the natural disease, and a pure culture of the organism was recovered from the lesion. Similar inoculation of grown hogs yielded negative results, older animals seeming more resistant to the infection than pigs one or two months of age. Rabbits were also infected by inoculation.

IMPROVED METHOD IN COMPLEMENT-FIXATION TEST.

The Pathological Division has devised an improved method for recovering trypanosomes from the blood of rats for antigen purposes in connection with the complement-fixation test which is used in the diagnosis of several diseases. A description of this method has been prepared for publication in the Journal of Agricultural Research.