Etiology. Pathogenesis. Anatomical Changes. 351 



pneumonia. If gastro-intestinal catarrh comes on after exces- 

 sive efforts (long rides, particularly during great heat, long 

 lasting railroad transportation) one may assume that a lower- 

 ing of the resistance of the organism as a whole had led to a 

 lowering of the resistance of the intestinal wall and had 

 exposed it to the detrimental effect of intestinal bacteria. 

 The intestinal aifection coming on within twenty-four hours 

 after excessive work ("Distanzrittkrankheit" [German] of 

 Heuss) has generally a hemorrhagic character and usually ends 

 fatally. 



Larger masses of sand which have found their way into the 

 gastro-intestinal canal sometimes cause gastro-enteritis in 

 horses (Mazulewitsch, Wenderniikow and others) and in hogs, 

 (authors' observation) owing to mechanical irritation and to 

 small injuries which open up portals for the invasion by bac- 

 teria. In this manner hogs often become affected when they are 

 transported in railway cars the floor of which has been covered 

 with sand. 



Pathog"enesis. Every gastro-enteritis is really due to 

 microorganisms or their toxins; their effect is not confined to 

 the intestinal wall but extends to the entire organism. Bac- 

 teria and their metabolic products are readily absorbed in the 

 inflamed intestine and then easily lead to general intoxication 

 or infection. This may occur the more easily since such intes- 

 tinal inflammations spread to the submucous tissue which is 

 quite rich in lymph channels. (Some bacteria can, even in a 

 healthy intestine, travel into the mesenteric gland and into more 

 distant organs as shown by the investigations of Porcher, 

 Desoubry, and more recently by Bogozinsky, Wrzosek & Ficker). 

 Hence gastro-enteritis is complicated from the start by more 

 serious general disturbances or by affection of more distant 

 organs. 



Anatomical Changes. The gastro-intestinal mucosa is af- 

 fected to a variable extent from case to case, sometimes more 

 uniformly, sometimes in patches, especially on the thick rugae 

 which are of a lively red color, either light or dark with punctate 

 or streaked hemorrhages ; there may also be more extensive suf- 

 fusions of blood. In the cases of gastro-enteritis of dogs which 

 the authors have observed, they found sometimes the mucosa of 

 the stomach, at other times that of the intestines, diffusely dis- 

 colored dark red and moderately swollen. The gastro-intestinal 

 contents are sometimes hemorrhagic, usually quite fetid. The 

 small hemorrhages in the stomach lead to the formation of 

 small, round, sharply defined erosions (erosiones haemorrhagi- 

 cae). The mucosa and submucosa are edematous, the submucosa 

 of the stomach sometimes sIioavs purulent infiltration (gastritis 

 purulenta sive phlegmonosa). The abdominal serosa is hyper- 

 emic (arterial injection). 



