THE DIGESTIVE SYSTEM 35 



where they produce fermentation and the gas evolved 

 is accumulated beneath the serous membrane. These 

 air cysts vary in size from a pinhead to a pea, and there 

 may be only a limited number of them or myriads. 

 Occasionally they are so prevalent that the intestine 

 will float on water. 



Enteritis 



Enteritis is inflammation of the intestine and may 

 be catarrhal, croupous, diphtheritic, mycotic; simple or 

 infective, acute or chronic. 



Catarrhal enteritis may be either acute or chronic. 



Acute Catarrhal Enteritis 



Acute catarrhal enteritis is a common ailment of 

 swine. 



Etiology. The usual cause of this disease is improper 

 food. The natural habits of swine are conducive to the 

 introduction of various microbes into their food and 

 drink, and swine are frequently fed on materials that 

 are partially decomposed. Their food not infrequently 

 contains chemical substances that are sufficiently irri- 

 tating to establish a catarrhal gastritis and enteritis. 

 The ingestion of foods of extreme temperatures may 

 excite catarrhal enteritis; not infrequently parasites 

 occur in sufficient numbers to produce local irritation of 

 sufficient extent to result in catarrhal enteritis; finally, 

 acute catarrhal enteritis may be associated with a variety 

 of infective diseases. 



Lesions. The lesions may be localized or they may 

 be general, involving practically the entire intestinal 

 mucosa. In the beginning the affected mucous mem- 

 brane is red, tumefied, and rather dry, but later it becomes 

 coated with mucous which is produced in excessive 

 quantities as the disease progresses. The submucosa 

 may be swollen, due to the accumulation of inflammatory 

 exudate. The tumefaction of the mucosa sometimes 

 effectually closes the ducts of the intestinal glands, thus 

 forming retention cysts, and the villi are turgescent and 



