CHRONIC INTERSTITIAL PNEUMONIA. 127 



may occur at any stage of the disease, in the early stages as a con- 

 sequence of great extension of lobular pneumonia, or at any time 

 as a result of oedema of the lungs. 



Chronic Interstitial Pneumonia. 

 {Chronio Induration of the Lungs ; Cirrhosis of the Lungs ; Phthisis.) 



When the disease terminates in this pathological condition we 

 find an inflammatory deposit in the interlobular and interstitial 

 connective tissue; this deposit compresses the alveoli and small 

 bronchia, and they lose their functions and are finally absorbed, 

 and on section of the affected portion of the lung it is found to be 

 coarse, rough, and irregular on its surface, the tissue varying from 

 yellow to yellowish-red in color. The bronchia surrounding the 

 affected, portion are distended and pocket-shaped, and there are 

 also a certain number of spots of localized emphysema. 



The clinical course of the disease shows very little fever, but 

 the animal is never entirely restored to health ; the respirations are 

 short, labored, and with a quick, weak cough. They finally become 

 emaciated, complicated with dropsical effusions, and finally die 

 from exhaustion. 



In some cases of lobular inflammation of the lungs the inflamed 

 portions form abscesses, or we may find gangrenous portions. These 

 terminations depend on the nature of the irritant, and generally 

 occur after traumatic pneumonia (foreign bodies). When an 

 abscess is formed a pear-shaped body is found in the centre of the 

 infiltrated lobule, and surrounding it is a thin, delicate layer of 

 yellowish tissue, and over that a tough red layer of inflamed 

 pulmonary material; large abscesses may be formed by the fusion 

 of all the infiltrated pulmonary tissue. 



When gangrene is formed the inflamed catarrhal centre becomes 

 dirty greenish-brown in color, or in severe cases almost black. In 

 the early stages the diseased portion is hard and fibrous, but it 

 soon becomes soft and pulpy and filled with a turbid, fetid, green- 

 ish serum. When the disease is slow and chronic the gangrenous 

 spots are limited in size, but generally when the disease assumes 

 the gangrenous form it becomes diffuse, and the animals die rapidly 

 from exhaustion . 



We recognize the gangrenous form when the breath becomes 



