246 Vomiting. 



causes vomiting'. For this reason vomiting is not infrequently 

 observed in carnivora and omnivora during the course of stom- 

 atitis, after the lodgment of foreign ])odies in the pharynx 

 (dogs often vomit after the ingestion of grass) and also during 

 convulsive attacks of cough. Finally," vomiting is often seen in 

 severe primary or secondary pharyngitis. 



Vomiting is of central origin (the stimulus originating in 

 the central nervous system) when it occurs with injury or dis- 

 ease of the brain or during transportation in ships (seasick- 

 ness). A similar origin is probably responsible for the occa- 

 sional vomiting of uremia or cholemia. 



There are certain chemicals which cause vomiting by irri- 

 tation of the emetic center (veratrine, apomorphine, chloro- 

 form). Hogs, dogs, cats are the domestic animals which vomit 

 easily and frequently; ruminants and rablnts with more diffi- 

 culty and more rarely ; horses quite rarely and only with great 

 difficulty in their attempt to expel the contents of the stomach. 

 Vomiting in horses is therefore of much greater significance 

 than in the other species of animals named. The differences as 

 to the various species are principally due to a lesser irritability 

 of the emetic center of the lierbivora and especially of the horse 

 when compared with other animals. The rarity of gagging, 

 which is parallel with the rarity of vomiting, likewise points to 

 this cause. The unfavorable anatomical conditions in the stom- 

 ach of the horse must act against the expulsion of the contents 

 of the stomach ; but they cannot explain the alisence of the char- 

 acteristic reflex motion, the gagging. That the influence of 

 anatomical conditions is much overestimated appears from the 

 observation that in acute dilatation of the stomach horses belch 

 a good deal but rarely gag and vomit. (Forssell claims that a 

 plug of mucosa in the region of the cardia closes the latter in 

 consequence of the displacement of mucosa on the loose sub- 

 mucosa.) 



Symptoms. Hogs, dogs and cats vomit without any partic- 

 ular efforts. After a certain degree of unrest, the head is 

 stretched, lowered to the floor, and the mouth then discharges 

 part of the gastric contents, particles of food mixed with mucus, 

 occasionally also with bile or fecal matter. In cattle vomiting 

 is preceded by greater restlessness and greater efforts ; the ani- 

 mal pulls back from the manger, the fore-legs tremble, the hind 

 legs are placed under the abdomen, the head is stretched out, 

 the mouth then expels after a short inspiration a large amount, 

 often more than ten quarts of fluid or of food. Horses make 

 similar and still more noticeable efforts; their whole deport- 

 ment betrays much excitement, the neck, the muscles of which 

 are very tense, is bent forward, the head is bent towards the 

 thorax, whereupon the vomited matter is mostly expelled 

 through the anterior nares. Vomiting is observed either as a 

 single act or it is repeated several times or it may last for hours. 



