Patliogeiiesis. 267 



the functional activity of the fore-stomachs, as does also pro- 

 lapse of the omasum into the thoracic cavity. Other causes are 

 tumors (see tumors of the stomach), diffuse lymphadenitis of 

 the wall of the fore-stomachs or of the abomasum (Eber), certain 

 diseases of the abomasum (obstruction by foreign bodies or feed 

 material, tumors, ulcerations), subacute or chronic peritonitis, 

 even if it has not caused adhesions of the fore-stomachs, clironic 

 disease of the liver (chronic interstitial inflammation, echinococ- 

 cus, tumors, gallstones), certain chronic diseases of the lungs and 

 heart. 



Pathogenesis. In consequence of the enumerated causal 

 conditions, especially, however, in consequence of continued im- 

 proper feeding, there occurs a diminution of the irritability or 

 of the energy of contraction of the fore-stomachs, or both func- 

 tions of the latter become diminished. The resulting weaker 

 and less frequent contractions of the fore-stomachs are the 

 cause of a deficient mixing and of a retarded removal of the 

 contents. According to prevailing conditions and amounts of 

 the feed contents, the degree of disturbance of function and the 

 amount of ingested water, there occurs either a lively forma- 

 tion of gas or the contents desiccate more or less ; even in the 

 latter case formation of gas is rarely absent. Every additional 

 act of ingestion of improper food further increases the disturb- 

 ances. 



No matter in what section the primary disturbance, desic- 

 cation of the feed always occurs in the rumen and omasum, 

 that is, in those sections where it is even normally less rich in 

 water than in the reticulum where the contents rarely desiccate. 



The reason for this Lehavior lies iu the functional inter-relation of the 

 individual sections of the stomach; stoppage of movements in one f-ection also 

 causes stoppage of movements in the other sections. It can not be tlenied, however, 

 that occasionally the omasum alone is the seat of the obstruction. This occurrence 

 is plausible since normally the contents of the omasum are comparatively firm, its 

 muscularis weak, and since finely divided feed (short cut chaff, bran, etc.) may 

 occasionally get directly into the third section of the stomach without rumination. 

 These are however rare cases and their differentiation from other forms of atony 

 appears impossible since disease of the omasum at once also leads to disturbance 

 of the functions of the other sections of the stomach. 



Incomplete mixing and accumulation of feed masses lead 

 to disturbances of digestion and to lack of nutrition, and these 

 again further increase the atony. Abnormal fermentation of 

 feed in the fore-stomachs may form poisonous decomposition 

 products, while the continued or often repeated dilatation leads 

 to a permanent dilatation of the fore-stomachs. If the affection 

 has lasted a long time, there also result inflammatory or even 

 necrotic changes of these sections. For these reasons ca- 

 tarrh of the abomasum and of the small intestines is one of the 

 common sequelae and the deeper inflammatory processes may 

 spread from the walls of the fore-stomachs into the peritoneum. 



