Etiology. Anatomical Changes. Symptoms. 263 



iiig or by the intestinal tract, is prevented for a considerable 

 time. The amount of gas formed may be normal or the gas 

 formation may be more lively than normal, without, however, 

 reaching a high degree. Chronic bloating occurs preferably in 

 atony of the fore-stomachs, both primary and secondary. 



Another frequent cause is traumatic gastritis, while in 

 calves and occasionally in lambs also, bloating is due to the 

 occlusion of the openings of the fore-stomachs or of the pylorus 

 l)y hair or feed balls. Disease of the abomasum likewise oc- 

 casionally produces chronic tympanitis. 



Another cause is stenosis of the esophagus (see page 231) 

 which prevents the removal of rumen gases by belching, and 

 also rumination. Stenosis of the esophagus is most commonly 

 produced l)y tuberculous mediastinal lymph glands as pointed 

 out l)y Johne. Weber and Goldmann have each reported a case 

 of compression of the lower end of the esophagus by large 

 echinococcus cysts of the liver. In a case of Ade, the lower end 

 of the esophagus was compressed by the reticulum wdiich had 

 entered the thoracic cavity through a slit in the esophagus. 

 Esophagus dilatation may also be the cause of chronic tympa- 

 nitis, l)ecause the former leads to occasional temporary obstruc- 

 tion of the esophagus. 



Hanioir is inclined to believe that it is not the stenosis of the esophagus 

 itself, but the compression of the pneumogastric nerve fibers which supply the 

 fore-stomachs that is the cause of chronic bloating (see also under stenosis of the 

 esophagus). 



Stenosis of the intestines may likewise be the cause of 

 chronic tympanitis. 



Anatomical Changes. Aside from the fundamental affec- 

 tion there is intensely fermenting food in the rumen, as well as 

 large amounts of gases. The gases contain less carbon-dioxide 

 than in acute bloating. In a case investigated bv Erdmann, he 

 found 42% CH4, 32% CO., 20% N. and traces of hydrogen. 

 Lungwitz found the proportion of hydrocarbons to carbon- 

 dioxide as 1.1 :1.2-1.5. 



Symptoms. Chronic tympanitis consists in a gradually in- 

 creasing, generally moderate, bloating of the left flank depres- 

 sion ; it occurs at first at irregular intervals, later, however, and 

 in profound cases, regularly after each feeding. It may excep- 

 tionally be present as a permanent condition. The degree of 

 bloating is influenced by the character of the food ; if the latter is 

 very fermentable, bloating is more noticeable and may then be 

 very extensive. The movements of the rumen may be perfectly 

 normal or, in severe cases, they are somewhat diminished or de- 

 cidedly sluggish. Rumination may be more or less suppressed 

 or completely abolished. In the latter case other gastro-intes- 

 tinal disturbances become manifest. 



