CHAPTER XI 



DISEASES OF THE ALIMENTARY TRACT AND OF 

 THE DIGESTIVE FUNCTION 



The digestive system includes the mouth, throat, 

 esophagus or gullet, stomach and intestines, with the 

 glands which pour their secretions into this tract, such 

 as the liver, salivary glands and pancreas. 



The differences in the mouths of animals are very 

 marked. In the horse the soft palate, or curtain between 

 the mouth and the throat cavity, is long, and is so 

 constructed that it prevents the horse from breathing 

 through the mouth. Cattle and sheep have no incisors, 

 or front teeth, on the upper jaw, but, instead, a pad 

 of cartilage against which the lower incisor teeth close 

 in biting grass. In pigs the teeth are set in a con- 

 tinuous row in the upper and lower jaws. In horses 

 there is an interdental space between the incisors and 

 the molars or grinders. In male horses there is in 

 this space a single canine or "bridle" tooth. These 

 are also found occasionally in mares. 



The stomach of the horse is rather small and the 

 bowels are capacious. In ruminants — those animals 

 which chew the cud, such as the cow and sheep — there 

 are four stomachs. The first is the rumen or paunch, 

 which lies on the left side. In adult cattle it has a 



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