118 C'rouiKius I'liciiiiiotiia. 



Errors of dia.iiiiosis may occur in pneimionia duriuiJ!: the 

 stage of hepatization, if a diagnosis has to be made on the 

 basis of a single examination or if the disease is complicated 

 by concomitant affections. One must think in this respect of 

 pleiiritis with effusion. Contrary to what is found in pneumonia, 

 dullness is, in pleurisy, always in the lowest portions of the 

 thorax, in horses it is usually on l)otli sides, the upper boundary 

 is almost without exception a horizontal line; the resistance 

 in the area of dullness is increased, In'eathing sounds cannot 

 be heard at all or onlj^ along the upper boundary; the disease 

 comes on slowly, fever is usually less high, the course of fever 

 irregular, breathing first of the abdominal type and later on 

 very forced ; dullness decreases or disappears after animal has 

 been laid down and vesicular breathing takes its place; in 

 smaller animals the dullness changes with changes in position in 

 such a manner that it always appears in the lowest place. When 

 pleurisy and pneumonia are present simultaneously some diffi- 

 culty as to differential diagnosis prevails because the con- 

 solidated lung as well as the pleural exudate l)oth cause dull- 

 ness, while breathing sounds are often absent over the con- 

 solidated portions of the lungs. Edematous infiltrations formed 

 on the lower thorax or lower abdomen may give some clue to 

 the existence of jileurisy along with pneumonia. In doubtful 

 cases an exploratory puncture should l)e made with a hypo- 

 dermic syringe. The procedure is perfectly harmless even in 

 the presence of an exclusive pneumonia. Only a positive result 

 of the exploratory puncture can be utilized for diagnosis, be- 

 cause puncture may be negative even in the presence of 

 pleuritic effusion. 



Catarrhal pneumonia may furnish similar physical findings 

 as croupous pneumonia if a number of small catarrhal foci 

 have become confluent and have formed one larger consolidated 

 area. However, bronchial pneumonia usually follows an ex- 

 tensive bronchial catarrh; it progresses slowly and lacks a 

 typical course. One should never forget that adult horses 

 usually suffer from croupous pneumonia, young foals and dogs 

 exclusively, or at least preferably, from catarrhal pneumonia. 

 The differential diagnosis from contagious pleuropneumonia in 

 cattle is very important. During the stage of hepatization the 

 findings may be identical in the two diseases ; hence a reliable 

 diagnosis can theu only be made under consideration of the 

 course. Contagious pleuropneumonia comes on gradually in 

 contradistinction to the sudden onset and cyclical course of 

 pneumonia, and cases with a comparatively rapid course last 

 several weeks. The possibility that the contagious disease may 

 be imported nuist always be considered. Inflammatory edema 

 at the entrance of the larynx or in other parts of the body in 

 the sanu» or in othei- animals, tlie sinuiltaneous occurrence of 

 enteritis and the rapid fatal termination, point to a septic origin 

 of pneumonia. 



