530 



DISEASES OF SWINE 



ner of giving the tuberculin test has been devised. This consists 

 in shaving the hair off of a small area on the skin and injecting a 

 drop or two of the test fluid between the layers of the skin. Not 

 under the skin. The animal is then left undisturbed for twelve 

 to twenty-four hours and the spot then examined. If a positive 

 reaction is obtained, the area surrounding the point of injection will 

 be found to be reddened and inflamed. In an animal which has 

 no tuberculosis the spot will be natural in color, and no change will 



Fig. 83. — Head inspection of hog carcasses. Over 95 per cent, of ca.ses 

 of tuberculosis of hogs show the disease in the glands of the head and neck 

 (U. S. Bureau of Animal Industry Report, No. 201). 



be seen as a result of the action of the tuberculin. This is what is 

 known as the intradermal method. It is very simple as compared 

 with the subcutaneous method, and in the hands of a competent 

 man is more reliable in the case of hogs. 



Postmortem Lesions.^ — When a tuberculous animal is opened up 

 after death certain very characteristic pathologic changes or lesions 

 are found. There are certain places in the body where these lesions 

 are particularly frequent, and in making an examination for tuber- 



