588 Tuberculosis. 



between 0.90 and 1.10 of the normal, 57.8% giving the same results with bovine 

 tubercle bacilli, while 21% of the healthy animals had indexes above the normal. 

 Moderately subnormal indexes (0.80-0.90) were observed in 8% of diseased as well 

 as in 8% of the healthy animals. Marked subnormal indexes were observed in such 

 cattle only as had been experimentally infected. 



Differential Diagnosis. Of the diseases resembling tuber- 

 culosis in clinical symptoms or anatomical changes the following 

 are of most importance. 



Contagious pleuro-pneumonia of cattle in its chronic or sub- 

 acute form: In this disease solidification of large continuous 

 areas of lung tissue may be recognized by the dullness revealed 

 upon percussion, bronchial respiration or the entire absence of 

 respiratory sounds, the pulmonary affection is always attended 

 with an acute pleuritis indicated by pain upon percussion, fric- 

 tion bruits, weak, suppressed and painful cough. There is less 

 secretion from the respiratory passages and the disease takes 

 a less insidious course than that observed in tuberculosis. In 

 very chronic cases a differential diagnosis is hardly possible 

 from the clinical symptoms alone, irrespective of the fact that 

 suspicion of the existence of pleuro-pneumonia does not exclude 

 the presence of tuberculosis, or that both diseases may exist at 

 the same time. 



Lung-worm disease in ruminants and swine. This is 

 usually an affection of younger animals, the cough is strong, 

 spasmodic and occasionally attended with attacks of choking; 

 there is rarely an elevation of temperature, auscultation reveals 

 fine rales and friction bruits, and the general condition of the 

 animals is usually little affected even after the otherwise pro- 

 nounced symptoms of disease have continued for some time. 

 Finally, the parasitic filaria may be demonstrated in the secre- 

 tions of the lungs and nostrils. 



A.ctinomycosis in cattle and swine. In this disease the 

 tumors of the udder and in the pharyngeal region are frequently 

 firmly attached to the overlying skin; if the tumors rupture 

 the characteristic ray fungus may be readily demonstrated 

 under low magnifying power without previous staining.' In 

 actinomycosis of the tongue the sublingual and pharyngeal 

 glands are not enlarged. Post-mortem examination reveals 

 yellowish granules imbedded in soft foci which are surrounded 

 by an abundant connective tissue. 



Ecchinococcus disease of the lungs. In this affection the 

 cough is weak and coarse, febrile symptoms absent ; the affected 

 animals may be in good condition in spite of the respiratory 

 troubles which may have persisted for a long period. Finally, 

 the disease is most frequently observed in young animals. 



Traumatic pericarditis. In contrast with tuberculous peri- 

 carditis, symptoms of accumulation of fluids (friction bruits, 

 dulled heart sounds in later stages, splashing and weak cardiac 

 sounds) are rarely absent. There is usually, also, more or 

 less swelling in the anterior thorax. 



