DIAGNOSIS. 505 



interlobular tissue augmented from the infiltration of a growth 

 of varying cellular and fibroid characters, the ultimate tendency 

 of which is to limit and circumscribe the pulmonary alveolar 

 structure, and thus to interfere with the function of respira- 

 tion. 



Diagnosis. — When the morbid action is chiefly developed in 

 the substance of the lungs we have less pain and distress ex- 

 hibited by the horse than in either bronchitis or pleurisy ; so 

 much is this the character of the disease that it is no uncom- 

 mon circumstance to have considerable structural change in 

 the pulmonary tissue ere we are aware of its existence. From 

 inflammation of the bronchial mucous membrane pneumonia 

 is also distinguished by the more regular occurrence of trouble- 

 some catarrhal symptoms in the former than the latter. In 

 bronchitis the cough is generally a prominent symptom, and is 

 always irritating and attended with pain. 



In pneumonia the respirations, somewhat or considerably 

 accelerated, are never of the distressing or marked abdominal 

 character they are met with in bronchitis and pleurisy ; and 

 while in pneumonia they bear no relation in distubance to the 

 rise of temperature and quickening of the pulse, they do in 

 pleurisy, and frequently also in bronchitis, bear this relation ; 

 i.e., the respirations increase in frequency in these in direct 

 relation to rise of temperature and frequency of pulsations. 



In pneumonia in the early stages we have crepitation 

 gradually displacing the natural respiratory murmur, and ter- 

 minating in loss of sound from consolidation ; in bronchitis we 

 have the early existence of the dry and sonorous rale, suc- 

 ceeded by the soft or mucous sounds ; in pleurisy the absence 

 of these, or, it may be, the addition to them of a distinct 

 rubbing sound, together with evidence of pain when the 

 animal is compelled to move, or smart percussion is employed 

 over the chest. 



In pneumonia the pulse is more variable than in either 

 bronchitis or pleuritis ; it is also of less resistance. In every 

 case, however, when forming an opinion as to the existence 

 and extent of pulmonary inflammation we must be guided not 

 by one class of symptoms, but all must be carefully observed 

 and collated with each other, the general with the physical, 

 and the physical and local with the general. 



