DIFFERENTIAL DIAGNOSIS 451 



number and bj' no means characteristic. The slight fever and 

 cough are the only symptoms of diagnostic importance in the 

 prodromal stage. In the second or acute stage a positive 

 diagnosis intra vitam can be made only when cases of pleuro- 

 pneumonia have previously occurred or when several occur 

 simultaneously. As a rule, a correct diagnosis can only be 

 made by a post-mortem examination. The following diseases 

 are to be differentiated from it : — 



1 . JSfon-infedious inflammation of the lungs. This may 

 be distinguished clinically, as a rule, by its more acute and 

 more typical course and by its sporadic and sudden appearance 

 and, anatomically, by the fact that the parts which have under- 

 gone hepatization are practically all of the same age ,and that 

 the interstitial lung tissue and pleurae are but slightly involved. 

 Nocard states that in exceptional cases pleuro-pneumonia may 

 run a very acute course and show hepatization of equal ages. 



2. Tuberculosis. The disease cannot be positively distin- 

 guished clinically from pleuro-pneumonia. Tuberculin may be 

 used as a diagnostic agent, although it is not at all certain 

 that animals which have suffered for some time from pleuro- 

 pneumonia do not react to tuberculin. After all, an anatomi- 

 cal examination is the only real test. Tuberculosis and con- 

 tagious pleuro-pneumonia have occasionally appeared simul- 

 taneously in the animal. See description of lesions in tuber- 

 culosis. 



3. Traumatic pneumonia or pneumonia due to foreign 

 bodies may exhibit the same symptoms as pleuro-pneumonia. 

 Evidence, during life, of changes in the heart caused by trau- 

 matic carditis will be conclusive in making the differentiation. 



4. Broncho or interstitial p7ieumonia. In making a diag- 

 nosis between contagious pleuro-pneumonia, based on the lung 

 lesions alone, it should always be borne in mind that the entire 

 lung should be subjected to examination. Attention should 

 be given to signs indicating injury to the chest wall, to the 

 possible presence of foreign bodies and to severe inflammation 

 of the air passages which may result from the aspiration of 



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