Subcutaneous Tu))ei-eulin Test. 



Oi.i 



more promptly and more energetically than that prepared from bacilli of the human 

 type. But the experiments of Weber and Dieterlin on cattle and guinea pigs^ 

 agreeing with the assertions of Koch, DeJong, Wolbach and Ernst, showed that 

 there was no difference in the two kinds of tuberculin, provided that both have 

 the same titre. However, since this is not ascertained in all preparations it is 

 advisable, in order to be safe, especially with ruminants and swine, to use tuberculin 

 exclusively that has been prepared from bovine tubercle bacilli. Tuberculin may 

 also be prepared from avian tubercle bacilli but this has a considerably weaker 

 action (Borrel). 



Later Koch made other tuberculin preparations from aqueous extracts of dried 

 tubercle bacilli or from dried bacilli finely ground in an agate mortar. The 

 whitish opalescent fluid obtained by centrifuging the first named extract represented 

 the preparation known as " T. O. ; " the fluid obtained by repeatedly mixing the 

 residue with water and centrifuging produced the tuberculin known as "T. R. " 

 The latter contains only substances contained in the bodies of the bacilli, and 

 none of their products of metabolism. Koch ascribes to it a special immunizing 

 action, but since it produces no reaction in tuberculous animals it has no value 

 for diagnostic purposes. 



The tuberculol of Landmann is prepared by extracting the fat from tubercle 

 bacilli, making further extracts by heating at various temperatures in physiological 

 salt solution and then concentrating the extracts in a vacuum. This preparation is 

 more toxic than other tuberculins. 



Finally there are also the simple culture filtrates of Denys and Detre which 

 have however not as yet l)een used in veterinary medicine. 



Standardization of Tuberculin. According to Koch 0.5 cc. of tuberculin 

 injected subcutaneously into a guinea pig that was infected four weeks before 

 must be sufficiently active to kill the animal within 30 hours, producing intense 

 inflammation at the periphery of the tuberculous foci. Von Behring indicates the 

 unit of toxicity of tuberculin by the minimum quantity (L+r— Timeswerth) which 

 will kill the test animals in 24 to 30 hours. The toxicity of the Marburg tuberculin 

 is suflficient for 0.2 gm. to kill a guinea pig weighing 400 gm. 



1. Subcutaneous Tuberculin Test (Thermal Tuberculin 

 Eeaction). The characteristic thermal reaction for tuberculosis 

 consists in a gradual rise of temperature beginning from the 

 6th to the 12th hour 

 after the subcuta- 

 neous injection of 

 the tuberculin, 

 reaching its maxi- 

 mum from the 12th 

 to the 21st hour, 

 thereupon falling 

 with slight interrup- 

 tions until the nor- 

 mal is reached at 

 the 24th to the 40th 

 hour. In some cases 

 a second rise of 

 shorter duration is 

 observed (see Fig. 

 93). The difference 

 lietween the maxi- 

 mum temperature 

 after injection and the temperature recorded before injection is 

 usually from 2° to 4° or 5° F. In rare cases the fever curve just 

 described may show variations in that it may begin sooner or 

 much later (14th to 18th hour), and then, particularly in the 

 latter case, reach the maximum at a later hour also. 



Fig. 93. Typical Tuberculin Reaction. 



