GASTBO-BNTERITIS 121 



directly or indirectly induce serious inflammations of the walls 

 of the gastro-intestinal tract. From catarrh pathologically it 

 varies only in degree; clinically it' differs in the intensity of 

 the symptoms and in the usual fatal termination. 



Occurrence. — Gastro-enteritis is common in all animals, 

 occurring as either a primary or a secondary disorder. 



Forms. — From a pathological standpoint, croupous, diph- 

 theritic, hemorrhagic, purulent, and phlegmonous forms are 

 distinguished; from a topographic duodenitis, ileitis, typh- 

 litis, colitis, and proctitis, depending upon the part of the 

 bowel tract involved. From a clinical standpoint the fol- v 

 lowing forms occur: 



(a) simple, (6) croupous, (c) mycotic, . (d) toxic. 



Simple Gastro-enteritis. — Etiology.— The causes of simple 

 gastro-enteritis are in a general way the same as those of 

 gastro-intestinal catarrh, but acting more intensively (see 

 these). Food which is infected with bacteria or fungi or 

 damaged by improper harvesting, frost, or containing poison- 

 ous, irritant weeds; or good food injudiciously fed may 

 therefore be predisposing factors. Overexertion, especially 

 in very hot weather (horses at hard work, animals shipped 

 long distances by rail, etc.), predisposes by greatly lowering 

 resistance. Copious draughts of cold water, the body being 

 hot, act in much the same way. 



The exciting causes of gastro-enteritis are evidently bac- 

 terial. Probably no one species, however, is a constant 

 cause. For some as yet unknown reason microorganisms 

 which are regularly found in the digestive tract assume 

 pathogenic activity once the resistance of the patient is 

 reduced by dietary errors, overexertion, extreme heat, etc. 

 It may thus be caused by some of the colon bacillus group. 

 The Bacillus enteriditis, the necrosis bacillus and the pus 

 bacteria seem to have been active in some cases. 



Animal parasites (Strongylus tetracanthus and Spiroptera 

 megastoma in horses, and spiroptera strongylina in swine) 

 are justly accused. 



In the ox a traumatic gastritis results from 1 foreign bodies 

 penetrating the walls of the stomach (see Traumatic Indiges- 

 tion of the Ox). 



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