86 Congestion of the Lungs and Edema of the Lungs, 



often lead to edema of the lungs even when compensated, 

 because the blood cannot flow freely from the veins of the 

 right side of the heart even when the heart muscle acts well. 

 Cardiac weakness exclusively of the left side is very rare as 

 long as the right side contracts powerfully ( Krehl). Hypostatic 

 hyperemia may also lead to edema of the lungs. 



Nutritive disturbances of the vessel walls in cachetic con- 

 ditions likewise predispose to edema of the lungs. 



Anatomical Changes. The consistency of the lungs is 

 somewhat increased in pulmonary hyperemia and they are 

 possibly also somewhat bloated, the cut surface is darker and 

 discharges blood freely. If the congestion has lasted a long- 

 time the lungs become tough in consequence of an increase of 

 connective tissue and the cut surface appears rust-brown o\\dng 

 to the presence of haematoidin granules (so-called induratio 

 brunea). Hypostatic hyperemia is usually found only on one 

 side or on part of one side ; here the pulmonary parenchyma 

 is of spleen-like consistency because the alveoli are filled with 

 blood corpuscles and blood plasma. This condition is called 

 splenization or, wrongly, pneumonia hypostatica. 



Pulmonary edema is recognized by a fine foamy fluid, mixed 

 more or less with blood, which oozes out in large amount from 

 the cut surface of the lung which has become less elastic. The 

 bronchi are filled by a similar fluid and the air contents is very 

 much diminished. One also observes the usual signs of death 

 from suffocation. 



Symptoms. The external symptoms of pulmonary hypere- 

 mia and of edema are on the whole very similar and consist 

 in the signs of rapidly increasing dyspnea and attacks of 

 suffocation. The animals appear at first anxious and restless, 

 but later on become listless and somnolent. The mucosae of 

 the head become cyanotic, the eyes protrude and the jugular 

 veins swell up. The respiration is much accelerated and forced 

 and soon becomes rattling. In edema of the lungs the much 

 dilated nostrils discharge a foamy, serous or serohemorrhagic 

 fluid. A short dull cough is heard periodically. The percussion 

 sound in hypostatic hyperemia is dull over the lower portions ; 

 otherwise it is normal or may be somewhat dull and 

 higher in pitch on account of the increased tension of the in- 

 tercostal spaces; in severe cases of pulmonary edema it is like- 

 wise dull, possibly here and there tympanitic. Vesicular 

 breathing is lessened in hyperemia, or on the contrary, rough ; 

 in edema it is much weakened, sometimes entirely absent; 

 crepitant and rattling rales may be heard. The heart beat 

 becomes pounding, the accelerated pulse is at first tense and 

 full, but later, or in concomitant heart disease from the start, 

 small and weak. 



All these symptoms may disappear as rapidly as they 



