DISEASES OF THE HOKSE. 23 



excepting on the back of the tongue, where the color is a yellowish 

 gray. As abnormalities of this region, the chief are diffuse inflamma- 

 tion, characterized by redness and catarrhal discharge; local inflamma- 

 tion, as from eruptions, ulcers, or wounds; necrosis of the lower jaw- 

 bone in front of the first back tooth; and swellings. Foreign bodies 

 are sometimes found embedded in the mucous-membrane lining of the 

 mouth or lodged between the teeth. 



The examination of the pharynx and of the esophagus is made chiefly 

 by pressing upon the skin covering these organs in the region of the 

 throat and along the left side of the neck in the jugular gutter. Some- 

 times, when a more careful examination is necessary, an esophageal 

 tube or probang is passed through the nose or mouth down the esoph- 

 agus to the stomach. 



Vomiting is an act consisting in the expulsion of all or part of the 

 contents of the stomach through the mouth or nose. This act is more 

 difficult for the horse than for most of the other domestic animals, 

 because the stomach of the horse is small and does not lie on the floor 

 of the abdominal cavity, so that the abdominal walls in contracting do 

 not bring pressure to bear upon it so directly and forcibly, as is the 

 case in many other animals. Beside this, there is a loose fold of 

 mucous membrane at the point where the esophagus enters the stom- 

 ach, and this forms a sort of valve which does not interfere with the 

 passage of food into the stomach, but does interfere with the exit of 

 food through the esophageal opening. Still, vomiting is a sj-mptom 

 that is occasionally seen in the horse. It occurs when the stomach is 

 very much distended with food or with gas. Distention stretches the 

 mucous membrane and eradicates the valvular fold referred to, and 

 also makes it possible for more pressure to be exerted upon the stom- 

 ach through the contraction of the abdominal muscles. Since the dis- 

 tention to permit vomiting must be extreme, it not infrequently hap- 

 pens that it leads to rupture of the stomach walls. This has caused 

 the impression in the minds of some that vom'.ting can not occur in 

 the horse without rupture of the stomach, but this is incorrect, since 

 many horses vomit and afterwards become entirely sound. After 

 rupture of the stomach has occurred vomiting is impossible. 



In examination of the abdomen one should remember that its size 

 depends largely upon the breed, sex, and conformation of the animal, 

 and also upon the manner in which the animal has l)een fed and the 

 use to which it has been put. A pendulous abdomen ma}^ be the result 

 of an abdominal tumor or of an accumulation of fluid in the abdominal 

 cavity; or, on the other hand, it may merely be an indication of preg- 

 nancy, or of the fact that the horse has been fed for a long time on 

 bulk}^ and innutritions food. Pendulous abdomen occurring in a work 

 horse kept on a concentrated diet is an abnormal condition. The 

 abdonlen may increase suddenlj^ in volume from accumulation of gas 



