subcutaneous injection of tuberculin does 

 not prevent the reaction. The test, however, 

 is not as sensitive as tlie subcutaneous or 

 intradermal tests and errors are consequent- 

 ly more frequent. (False negative reactions.; 



The Intradermal (intracutaneous) Test— 

 This test, ranking as it does as one of tlie 

 most sensitive of the tuberculin tests, has 

 rapidly gained in favor among the veteri- 

 nary profession since its introduction by 

 Moussu and Mantoux, on account of its ac- 

 curacy and convenience, especially when ap- 

 plied to range cattle or swine. 



Technic Intradermal Test (Haring and 

 Bell). — The tuberculin is injected in 1/20 to 

 Vi c.c. amounts into the deeper layers of the 

 skin of the subcaudal fold. A 1 or 2 c.c. 

 syringe graduated to tenths armed with a 25 

 to 26 gauge needle and having a point 3/16 

 to Vi of an inch in length is suitable for this 

 work. When properly injected the tubercu- 

 lin may be felt as a small lump in the skin 

 after tlie needle has been removed. A solu- 

 tion of precipitated tuberculin at least 5% 

 strength in doses of 1/10 to 1/5 c.c. is rec- 

 ommended, though Vz c.c. of a 25% solution 

 produces no liarmful results. 



A Positive Intradermal Reaction — Is indi- 

 cated by a thickening of the subcaudal fold 

 or by the appearance at the point of injec- 

 tion of a characteristic sensitive swelling 

 varying in size from that of a small pea to 

 that of an orange. The swelling may be 

 either soft and edematous or hard and in- 

 flamed. A recognizable reaction may be 

 present on the sixth hour, but generally the 

 reaction is first clear about the 12th hour 

 and continues to increase in size until the 

 48th hour. In some instances we have ob- 

 served that the early local reactions disap- 

 pear before the 48th hour, while in others 



avv3a2»«»w.y.="n -. / Jr.Tf.wci'swii^— » - 



