28 



BULLETIN OF 

 MASSACHUSETTS BOAED OF AGRICULTURE. 



VETERINABY. 



The Diagnosis and Eradication of Tuberculosis. 



PART II.* 



The question is often asked the veterinarian by practical stock- 

 men, "How can I tell when my cattle have tuberculosis?" I 

 answer that it may be detected in most well-marked cases by the 

 physical symptoms, — the general condition of the animals, with 

 the knowledge of the previous existence of the disease in the herd. 



But in eradicating this disease from a herd it is necessary that 

 we remove all affected animals, no matter how slightly diseased, 

 for if one is left it soon becomes a centre of infection and others 

 coming in contact or being kept in the same stable soon become 

 the subjects of the affection. The disease is so insidious in its 

 attack and the general disturbance so slight in its incipiency that 

 it becomes an impossibility by an ordinary examination to make a 

 correct diagnosis. 



These uncertain and occult cases are the ones which prove so 

 troublesome to the stockman and veterinarian. Possibly by one 

 of three methods may a correct diagnosis be made. 



First. By microscopical search for the germ. In some instances 

 these are found in the mucous material from the nostrils, the milk 

 or perhaps in the contents of abscesses. 



Second. By the inoculation of susceptible animals, such as rab- 

 bits or guinea-pigs, with some substance which may contain the 

 micro-organism. 



Third. By the use of tuberculin. 



The first two methods are not as easy of application or as reliable 

 as the third. All are suitable only for the veterinarian. The use 

 of tuberculin as a diagnostic agent in tuberculosis is comparatively 

 of recent origin. Although it has been experimented with for sev- 

 eral years its value has been but recently proved. 



Tuberculin or Koch's lymph is a substance which was prepared 

 by the German bacteriologist Koch for the cure of consumption in 

 * For Pan I see Bulletin No. 2. 



