11 



no means always true. As will be shown farther on, many cases of 

 slight tuberculosis show no reaction. The latter are usually old 

 cases. P'rom the degree of the reaction, conclusions as to the devel- 

 opment of the disease must be drawn with great care. 



The question arises, how much dependence can be placed on tuber- 

 culin as a diagnostic agent? A. P^ber^^ has recently made 563 inoc- 

 ulation tests, in various places, and states that dissections corrobor- 

 ated the tuberculin diagnosis in 489 cases, and failed to do so in 74 

 instances, this amounts to 86.86 per cent and 13.14 per cent respect- 

 ively. In Denmark similar, though better, results have been 

 obtained. 515 dissections showed 50 false tuberculin diagnoses i. e. 

 9.7 per cent. 



The false diagnoses are of two kinds, either the animal reacts with 

 tuberculin without showing a trace of the disease at the autopsy, or 

 the autopsy shows tuberculosis where the tuberculin failed to react. 



As tuberculous deposits found in reacting animals are often so 

 very insignificant, one cannot lay particular significance on their 

 reported absence, unless entire confidence is to be placed in the 

 experience and care of the investigator. Knots from the size of a 

 needle's head to that of a pea in a hidden lymph gland surrounded 

 by fatty tissue, may be overlooked even by those of much experience. 

 In the case of animals intended for the butcher, all of the parts can- 

 not be carefully investigated and doubt therefore always accompa- 

 nies a negative result. From my personal observation I know of 

 three cases of typical reaction in which it was impossible for me to 

 discover tuberculous deposits. In two of these the animal was entirely 

 healthy. ^^ The third was a fifteen year old cow. This animal 

 stood among those which reacted at Thurebylille and had reacted 

 every year from 1892 to 1895. She suffered from pyelitis and 

 chronic fibrous nephritis. In the diseased organs no tubercle bacilli 

 could be discovered, but streptococci and other bacteria were pres- 

 ent. This is the only case within my observation in which appar- 

 ently the reaction was to be explained by the presence of a non- 

 tuberculous chronic disease. Such cases are often mentioned in 

 literature, but I wish to call attention to the fact that an animal 

 suffering from cancer or actinomycosis very often suffers from tuber- 

 is. Deutsche thierarztl. Wochenschr. No. 20. 



19. Compare " La lutte centre la tuberculose en Denmark " p. 30. The one ani- 

 mal "was a young cow and the other a 6 nios. old calf. This animal was butchered 

 Sinos. after the inoculation. It might be possible that the infection had recently 

 taken place and that thus tuberculosis was not yet visible to the naked eye. 



