154 Chronic Interstitial Pneumonia. 



further cause of chronic pneumonia may be the inhalation of 

 dusthke bodies (fragments of plants, silicon-, lime- or coal- 

 dust), which are absorbed from the bronchi into the interstitial 

 pulmonary tissue, and there produce a usually circumscribed, 

 occasionally, however, a more extensive, chronic inflammatory 

 process. (Pneumoconiosis.) Larger foreign bodies which 

 have penetrated into the lungs from the air passages or from 

 the fore-stomach may exceptionally produce chronic intersti- 

 tial pneumonia. Schmidt observed a traumatic inflammation 

 of the stomach, diaphragm and lungs in a horse with bronchi- 

 ectasis. 



Vansteeiiborglie & Grisez claim, on the basis of their animal experiments, that 

 pulmonary anthraeosis is not caused by the inhalation of dust-like foreign bodies, 

 but by the absorption of dust-like bodies, which are swallowed and only secondarily 

 brought from the intestines into the pulmonary vessels. Numerous experiments 

 which Avere stimulated by the above statement have, however, proved that the 

 dust-like foreign bodies in natural affection do get into the lungs by inhalation; 

 anthraeosis of intestinal origin is observed only exceptionally and then it does 

 not reach a high degree (Liittschwager). 



As a rule, the disease is a secondary affection, seen par- 

 ticularly after bronchial catarrh. When existing for a long 

 time, this leads to the new formation of connective tissue in 

 the bronchial wall and finally spreads to the neighboring inter- 

 lobular connective tissue. Purulent catarrh of the bronchi, giv- 

 ing rise to chronic pneumonia, occurs frequently in cattle, hogs 

 and sheep. Polyadenomatous proliferations in sheep (Prosch) 

 and cats (Ball) may have a similar origin, but they are rather 

 to be looked upon as true tumors (q. v.). The process arises 

 not uncommonly from atelectatic foci (see page 131). In pro- 

 tracted cases of acute pneumonia a progressing inflammation 

 in the connective tissue is also seen, surrounding the affected 

 lobules. This termination is observed particularly after ca- 

 tarrhal pneumonia, more rarely after croupous pneumonia, 

 where, if seen at all, it occurs usually in old debilitated animals. 

 An inflammatory new formation of connective tissue also oc- 

 curs in the neiglil)orhood of encapsulated abscesses, putrid or 

 caseous foci, parasites, tumors, etc. Chronic pneumonia also 

 occurs in the course of chronic pleuritis. Certain chronic in- 

 fectious diseases also always finally lead, in their localization 

 in the lungs, to chronic connective tissue inflammation. 



Anatomical Changes. The affected pulmonary portion 

 a])pears firmer, touglier, more tenacious, it contains less air, 

 the cut surface shows a few cicatrices or cicatrixlike stripes 

 between the air-containing lobules, or a whole portion of lung 

 may be changed into an almost homogenous, firm, airless tis- 

 sue, in which one can see only here and there an air-containing 

 lobule. The shrunken portions of lung sometimes contain case- 

 ous foci and abscesses. 



In lardaceous pneumonia of horses the upper portions of 



