Section IV. 



DISEASES OF THE LUNGS. 



1. Congestion of the Lungs and Edema of the Lungs. 

 Hyperaemia et Oedema pulmonum. 



Hyperemia of the kings consists in an abnormally high 

 amount of blood in the pulmonary capillaries, which may be 

 due to an increased inflow of blood (hyperaemia pulmonum 

 activa) or the condition may be brought about because, for 

 some reason or other, the blood cannot flow without impediment 

 from the lungs toward the left side of the heart (hyperaemia 

 pulmonum passiva). Edema of the lungs occurs in consequence 

 of an extravasation of serous fluid into the alveoli and 

 bronchioles and also into the interalveolar tissue. 



Etiology. Hard labor may produce an increased supply 

 of blood to the lungs, since the heart which works energetically 

 and rapidly nmy bring an increased amount of blood into the 

 pulmonary artery. Active hyperemia on this basis, therefore, 

 frequently occurs in racers, in hunters and army horses, and 

 in hunting dogs, especially in summer when the warm air also 

 has a weakening effect upon the pulmonary vessels. In a con- 

 sidera])le proportion of such cases we are, however, rather 

 dealing with heat-stroke or with acute cardiac weakness due 

 to passive hyperemia (for details about the disease called 

 "summer foundering" by Bongartz, see in the chapter on heat- 

 stroke). 



The disease under discussion appears in horses and, per- 

 haps, also in other annuals in combination with rheumatic affec- 

 tion of the intercostal muscles, during long railroad transpor- 

 tation, particularly if the animals are crowded in the car 

 (Dieckerhoff, Sigl"). Overheating of the body, exertion and 

 excitement are probably the injurious factors (Dieckerhoff' de- 

 scribes this condition as a disease sui generis under the name 

 of Pleurodynia). 



Very hot air or air mixed with acrid and irritating vapors 

 may produce an increased blood supply by dilating the pul- 

 monary vessels or by acting as an inflammatory stimulus ; this 

 has been shown by observations made after conflagrations. 



84 



