150 TUBERCULOSIS 



tered were tuberculous. In this and most countries there are 

 no reliable statistics respecting the extent of the disease in 

 this species. M'Fadyean has pointed out the fact that in a 

 considerable number of cases of equine tuberculosis, where the 

 horses have been fed milk from tuberculous cows, the morbid 

 anatomy differs but slightly from that in tuberculous cattle. 



Sheep and other domestic animals are reported to suffer 

 more or less extensively from this disease. All of the so-called 

 tuberculosis in sheep and fowls which I have been able to ex- 

 amine proved not to be tuberculosis but animal parasitisms 

 such as the "nodular disease of sheep" and "taeniasis" in 

 fowls. 



^^ 115. Differential diagnosis. Tuberculosis is to be 

 differentiated from actinomycosis, glanders, and various parasit- 

 isms resulting in nodules largely in the walls of the intestine. 

 In cattle the nodules are produced by an Oesophagostoma, in 

 sheep the nodules are caused by Oesophagostoma Columbianum 

 Curtice. In chickens a nodular taeniasis of the intestine is not 

 infrequently mistaken for tuberculosis. Abscesses and necrotic 

 foci due to various agencies must also be distinguished from 

 tubercular lesions. 



In cases of actinomycosis, the ray fungus can usually be 

 detected on a microscopic examination. Bad. mallei can be 

 found either in cultures or by guinea pig inoculations in cases of 

 glanders, and in parasitic diseases the specific animal parasite 

 can be found if diligently sought. A careful study of the 

 recent lesions, especially in the nodules caused by the animal 

 parasites will show that they are not structurally like the 

 tubercle as described above. 



From the symptoms and morbid anatomy it is clear that 

 hard and fast lines for diagnosing tuberculosis cannot be laid 

 down. As a rule, the lesions are characteristic although there are 

 many exceptions. In making a positive diagnosis, one must rely 

 upon the discovery, microscopically, of the specific bacterium, 

 the result of animal inoculation or the effect of tuberculin. 



The tubercle bacteria can be found by making and properly 

 staining cover-glass preparations from the tuberculous tissues 

 or discharges in a certain number of cases. When these tuber- 



