164 CONTAGIOUS diseases; 



When the disease is confined to one lung, the respiratory 

 murmur in the healthy lung is louder than natural, owing to its 

 having to admit more air than when both are in a state of health. 

 This must not be confounded with a diseased condition ; and in 

 order not to make a mistake, percussion must be applied, — the 

 healthy side will be resonant, the diseased one dull. I have seen 

 some cases where the diseased and consolidated lung has enlarged 

 to such an extent as to push the ribs immediately covering 

 it outwards to some extent, the animal appearing rounder and 

 larger on that side in consequence ; and some of these cases 

 have afterwards thriven and become fit for the butcher. 



Now and then it is found that some portion of the lung 

 becomes gangrenous, and is coughed up ; these cases are, how- 

 ever, very rare. When gangrene occurs, the discharge from tlie 

 nose is sanious and foetid, and a fcetid diarrhoea soon carries off 

 the suffering beast. Abscesses in the lungs are an occasional 

 consequence. An animal apparently recovers from the disease ; 

 but after a time begins to lose flesh, and sinks from exhaustion, 

 the jpost mortem revealing caseous tumours or a large abscess or 

 abscesses in the lungs. In some instances of very extensive 

 consolidation, the sounds detectable by auscultation and those 

 emitted by percussion are very trivial. In such it is found tliat 

 the alteration of structures is most extensive in the central 

 portion of the lungs. One symptom is very diagnostic of this 

 condition— namely, much coughing when the animal attempts 

 to swallow ; this is caused by the exudate pressing upon the 

 oesophagus within the chest, and retarding the action of deglu- 

 tition. When the exudate presses upon the large blood-vessels, 

 there may be turgescence of the jugulars and the venous pulse. 



POST MORTEM APPEARANCES. 



On opening the chest of an animal which has been slaugh- 

 tered early in the disease, the visible changes are dulness of the 

 affected pleural surfaces ; the substance of the lungs, particu- 

 cularly of the large lobes, is red, congested, and more or less 

 consolidated ; the redness and congestion being often in patches, 

 each patch being generally surrounded by whitish bands of 

 thickened interlobular tissue, giving them a marbled appearance. 



