314 STATE BOARD OF AGRICULTURE. 



In ConiK'c'licut, of C,:}04 tcsttd, 14 2-10 per cent reacted. Of 2,417 tested in 1895 in 

 New York state, 405 reacted. Of 849 cattle tested in Michigan by Dr. GraJige, 107 

 reacted, or 13 per cent. Dr. Diiiipiiy, now Stale N'cteriiiariaii. reports that about 13 

 per cent of the animals tested hy him in ^licliif^an are tiiln-rciilous. 



The statistics rehiting to tlie number of animals tested and reacting in the State 

 of Micliigan do not represent tlie true extent of the disease, for it is a fact that most 

 of the herds tested by the State Live Stock Sanitary Commission liave belonged to 

 State institutions, or growers of blooded stock, and have consisted of higlily-bred 

 stock, wiiich seem to be either more susceptible to tuberculosis or liave been the avenue 

 by which the disease has entered the State througli importation. Tlie College, 

 in the summer of 1897, purchased thirty grade dairy cows in dillVrent sections of the 

 State, not too far distant from Lansing. These cows were brougiit to the College 

 and tested witli tuberculin. Not one reacted. Only one developed tuberculosis the 

 year following and in this case the disease was in its incipient form. The author has 

 made a test of several grade animals since in the vicinity of the College, but has not 

 found tuberculosis in a single case. Although aware that our evidence is too limited 

 to form a wholesome judgment of the amount of tuberculosis prevaiTing among 

 cattle in the State of ^Michigan, my contention is, do we not have less than would be 

 indicated by the report of the State Sanitary Commission, since in all likelihood the 

 native herds possess a freedom from this disease, not belonging to pure-bred stock 

 unless introduced into the herd through the introduction of slran^'c animals? 



DISSEMINATION OF TUBERCULOSIS. 



Various methods by which this disease is transmitted from one to another in. the 

 human family may furnish us with sufficient data to understand the various avenues 

 of dissemination in the bovine species. Perhaps the most common path of contagion is 

 through the sputum, which leaves a tuberculous subject, linds its way to the ])ave:iient, 

 floor or ground, becomes dessicated, pulverized, enters the dust of the air and eventually 

 lodges in the respiratory tract of some individual prepared to contract the disease. 

 Again, it may become lodged in the handkerchief, dried and by this method furnish 

 another channel by whicli it enters the respiratory organs. It has also been deter- 

 mined that the fine, invisible salivary spray that passes from the mouth contaminated 

 with tubercle bacilli may contain the germs of this disease. Experimentalh', the possi- 

 bility of such infection has been shown through the administration of atomized 

 tuberculous liquids to animals. 



In our study of the discharges from the nose and mouth of the tuberculous animals 

 we have had under our charge, we have been able to demonstrate the presence of 

 tubercle bacilli in two or three cases. In one case in particular, the tubercle bacillus 

 was exceptionally numerous. That this is one of the most coinmon means of conveying 

 the disease from one animal to another can scarcely be doubted, as Dr. Ruhling of 

 Gottingen pointed out in 1774. by the following statement: "The malady is trans- 

 mitted to sound animals by direct contact of animals standing side by side and licking 

 each other and l)reathing the expired air direct from the diseased lungs; the fre- 

 quenting of the same pastures will also serve to propagate it." It is a very common 

 occurrence to find upon testing with tuberculin that animals adjacent to a tuberculous 

 animal are more likely to be tuberculous than any others in the herd. The autlior's 

 attention has been called to a very interesting case in which a test had been made and 

 tuberculosis found very prevalent. An efTort was made to build up a new herd 

 out of the ofTspring of the old by isolation. It was supposed that every avenue of 

 infection was shut off, but the young animals continued to contract the disease and 

 the cause of this infection was not explained until it was found that the owner, in 

 establishing his isolation, had neglected to look into the v/ater supply, which flowed 

 from the drinking trough of the old herd to the voung stock. When this was attended 

 to, no more developments appeared. The sputum evidently from the old herd or nostril 

 discharges entered the drinking water and was carried to the young herd. I have 

 picked up discharges, coming from tuberculous cows, on straw in the stalls, which, 

 upon examination, showed tlie presence of tuljercle bacilli. Therefore the discharges 

 from the mouth and nostrils of tuberculous animals are fraught with exceeding danger, 

 and, through the various avenues, reach sound animals and produce in the susceptible 

 of them this fearful disease. 



The feces is a carrier of tubercle bacilli at times. It is possible for the sputum 

 coming from the lungs to be swallowed, conveyed through the intestines and issued 

 from the body in the fecal matter. As evidence of this, a case here at the College 

 may be adduced : A cow which had tuberculosis of the lungs and the pleural lining. 



