OF VETERINARY MEDICINE. 105 



DISEASES OF THE STOMACH, 



VOMITION. 



Vomition is called emesis or vomiting. The emetic center is 

 in the medulla. Something disturbs this center, and the reflex 

 action of the disturbance is transmitted to the stomach. The 

 symptoms of vomiting are : 



1. Depression. 



2. Turning up of the upper lip. 



3. Abhorrence of food. The nausea in- 



creases until we get a reflex peris- 

 talsis of the stomach, duodenum and 

 sometimes of more of the small in- 

 testines. 

 The act of vomiting is as follows: 



1. Deep inspiration. 



2. Glottis fixed. 



3. Spasmodic forcible contraction of the 



abdominal muscles. 



4. Food thrown out through the nose, 



5. ^louth in all animals except the horse 



wide open. 



The stomach cannot empty itself without the aid of the 

 abdominal muscles. 



Horses do not vomit except under peculiar conditions ; carn- 

 ivora vomit easily ; omnivora comparatively so : and herbivora 

 with o^reat difficultv. Cattle do not vomit because the rumen is 

 large and comparatively insensible. As a whole the ox is phleg- 

 matic. Horses vomit with difficulty on account of the shape of 

 their stomach. At the oesophageal entrance there is a fold of 

 mucous membrane which acts as a valve and serves to keep the 

 food from going back toward the mouth. Except in case of a 

 distended stomach vomition cannot occur. It is usually accom- 

 panied with gas. There are four conditions under which a horse 

 vomits : 



1. Stomach distended with gas and food 

 mostly liquid. 



