412 DISEASES LOCALIZED IN CERTAIN ORGANS 



establish beyond doubt the existence of the disorder. A clear 

 history of the prevalence of the disease in the country or 

 community, the insidious onset, the fact that only a portion 

 of the cattle are attacked at the same time and the clinical 

 evidence of pneumonia are very suggestive if not convincing. 

 Lung plague can be confused with : 



(a) Hemorrhagic Septicemia (Pectoral Form). — While this 

 disease usually has a sudden onset, is much more acute 

 and attacks larger numbers of animals simultaneously, some 

 acute cases of lung plague may greatly resemble it, not only 

 clinically but on necropsy. In doubtful cases only a bac- 

 teriological examination (finding bipoled bacillus; animal 

 inoculation) will determine. 



(b) Tuberculosis (Pulmonary) may be confused with a 

 chronic case of lung plague. The absence of continued fever, 

 lack of pleural symptoms, the even more chronic course of 

 tuberculosis and the results of the tuberculin test usually 

 suffice to differentiate between the two. However, lung 

 plague and tuberculosis may occur concomitantly in the, same 

 animal. 



(c) Pneumomycosis (Aspergillosis of the Lungs) is rare in 

 cattle, affects most often birds. The development is very 

 slow; little fever. On necropsy the presence of Aspergillus 

 fumigatus in the bronchi and consolidated lung tissue is 

 conclusive. 



(<^) Verminous Bronchitis. — Affects mainly calves. Cough- 

 ing prominent. Parasites or eggs occiu- in the ejections. 



Course. — ^The course of the disease is varied. Many cases 

 recover during the early stage and after only a few days ill- 

 ness. In others recovery is slow and often imperfect, pul- 

 monary sequestra remaining. Such an animal^ as noted, is a 

 dangerous source of infection. 



The course is generally more stormy in young, well nour- 

 ished patients, although calves are quite resistant. The 

 mortality is usually from 60 to 70 per cent. Not over 20 to 

 30 per cent, fully recover. A number remain chronically 

 affected, but may fatten. 



Depending on circiunstances, the disease may persist on a 

 given premises for years. This is particularly true where 



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