92 Chronic Alveolar Bloating-. 



are present a diagnosis can be made safely, provided chronic 

 alveolar pulmonary emphysema can be excluded. 



Treatment. This depends entirely upon the primary dis- 

 ease. Its removal must be sought for because its persistence 

 entails danger of the develo2:»ment of lasting chronic dilatation 

 of the alveoli. 



(b) Chronic Alveolar Bloating. Emphysema pulmonum alveolare 



genuinum. 



{Ilcavcs: Emphysema pubn. alv. st(hstanfialr.) 



Chronic alveolar bloating of the lungs consists in a per- 

 manent dilatation of the alveoli accompanied by atrophy of the 

 interalveolar and the interinfundibular septa and of the vessels 

 contained in them. 



Occurrence. Chronic emphysema of the lungs is found 

 preferably in horses, more rarely in working oxen, quite fre- 

 quently in hunting dogs, usually in canines that are somewhat 

 advanced in age. It is the most common cause of horses being 

 broken -winded. 



Etiology. Chronic emphysema of the lungs develops, as 

 a rule, after the animals have been used a long time for heavy 

 work (pulling or running) ; it is more rarely due to continued 

 inspiratory or expiratory dyspnea in chronic diseases of the 

 air passages. Since continued inspiratory dyspnea is rare as 

 long as the air can stream into the lungs, it plays only an 

 insignificant role in the production of chronic pulmonary em- 

 physema. A more potent and more frequent cause of the affec- 

 tion is difficult expiration, which is occasionally simultaneous 

 with inspiratory dyspnea. 



Long-continued and convulsive cough is more dangerous 

 in this respect than impeded expiration, because a deep inspira- 

 tion precedes every effort at cough and this produces a liigh 

 air pressure in the lungs. On account of narrowing of the 

 bronchial lumen by plugs of mucus or swelling of the mucosa, 

 the escape of air out of the alveoli is impeded in catarrh of 

 the finer bronchi. These circumstances sufficiently ex])lain why 

 chronic bronchial catarrh so frequently leads to emphysema 

 of the lungs. Ball saw several cases of chronic emphysema 

 in cats following multiple bronchial adenomata. 



The presenee of chionic bioiu-hial catarrh in emphysema of the lungs floes 

 not ])er se prove that the latter is always eansed by the former, because emphysema 

 may exist and only subsequently lead to bronchial catarrh. 



Emphysema of the genuine or substantial type may arise also from 

 other causes aside from tliose already enumerated, and a permanent dila- 

 tation of pulmonary alveoli with atrophy of the pulmonary tissue may 



