THE LUNG PLAGUE. 19 



persons can, with a little care, distinguish the sick from healthy cattle by listening to the 

 sides of the chest. It does not require a skillful expert to recognize that the ribs are 

 motionless and flattened over the consolidated lung, that there is an absence of resonance 

 on striking the ribs over the affected region, and that the ear distinguishes a very distinct 

 respiratory murmur wherever the lung is pervious, and an absence of this sound where 

 the lung is transformed into a solid mass. 



At an early stage of pleuropneumonia there is a harsh sound, roar, or rhonchus, pro 

 duced by the passage of air through the windpipe and its subdivisions. This varies in 

 intensity in different cases, as some animals have more exudation on the mucous surface 

 of the air passage than others, and the leathery-looking shreds of lymph adhering to the 

 inflamed membrane vibrate as the air rushes past them, giving rise to the harsh sound 

 which may sometimes be heard by persons standing by a sick animal. In many cases 

 one lung alone is affected, and then the respiratory murmur is more distinct than in health 

 wherever the lung tissue is pervious, whereas there is a total absence of sound over the 

 consolidated organ. Occasionally an air passage remains open through a mass of hard 

 ened lung, and the air rushing through this rigid bronchial tube makes a very decided 

 whistling noise. 



In the earliest stages of pleuropneumonia the deposit of lymph on the serous cover 

 ing of the ribs and lungs produces a leathery-friction sound, and as liquid accumulates in 

 one or both cavities of the chest the respiratory murmur is lost towards the lower part of 

 the affected side or sides, and it is alone distinct over the upper portions of pervious lung 

 tissue. 



A careful examination of the chest reveals, day by day, the progress of the disease. 

 When one lung is affected an animal is much more likely to recover than when both are 

 diseased. Portions of the diseased lung tissue are apt to die, and, becoming detached or 

 softened, produce cavities in the lungs, which are indicated by a cavernous rale or sound 

 somewhat similar to that produced by blowing air in the hollow of the hands when closed 

 against each other. 



By careful auscultation the cases that tend to convalescence may be distinguished by 

 less marked roughness in the inspirations, and a gradual though slow return of the respira 

 tory murmur, with increased mobility of the ribs and easier movement of the flanks. 



TEEMINATION. 



Cases of lung diseases in cattle end in partial or complete restoration to health, or 

 death by prostration, suffocation, purulent fever, or hectic. 



As a rule, when a herd of cattle has suffered from the contagious pleuropneumonia, 

 the surviving animals, whenever slaughtered, show old adhesions, partial collapse of the 

 lung tissue, atrophy or wasting of the lung, thickness of the heart s covering or pericar 

 dium, and sometimes chronic abscess. Complete recovery without leaving the slightest 

 traces of pre-existing lesion occurs. It has been noticed that cattle that have once had 

 pleuropneumonia fatten more readily than others. 



Death supervenes during the acute attacks of the disease from shock, prostration, or 

 gradual suffocation. When animals linger on for some time in the bloodless state peculiar 

 to this disease, and which is mainly due to the great drain on the system by the immense 



