DIGESTIVE APPARATUS. 137 



■defects of the teeth exist. Shear jaws, and irregular teeth, 

 projecting teeth, etc. The animals masticate one-sided, cau- 

 tiously and "easy ;" they don't masticate thoroughly, the food 

 is "crushed and bruised" but not "ground." 



Mastication is painful when acute inflammatory condi- 

 tions exist in the cheeks, temporo-maxillary articulation and 

 in the intermaxillary space as they occur in the course of 

 ■distemper of horses. Mastication may be voluntarily inter- 

 rupted. If sharp or pointed objects like nails, needles, splin- 

 ters of wood, etc., are taken up with the food horses open 

 their mouths wide and allow the contents to drop out, aiding 

 with the tongue. They do the same thing when injuries 

 are produced by sharp teeth or displaced teeth (alveolar 

 periostitis) ; sudden pain, produced by biting on a diseased 

 or loose tooth, produces the same effect. Horses with dis- 

 eased teeth frequently drop small masses or balls of food 

 into the manger, "quibbing." Some horses suddenly raise 

 their head while masticating and hold it sideways, open the 

 mouth and continue masticating in a cautious manner, at the 

 same time making slow lateral . movements with the lower 

 jaw. Varied as the symptoms that occur in the course of 

 different affections of the teeth may be, they all have 

 o n e t h i n g i n c o m m o n . t h e }• make mastica- 

 tion difficult and painful. 



In dangerous diseases we often observe gnashing of the 

 teeth, at the same time this is not a "prognostically unfavor- 

 able" sign. 



d. Deglutition. Deglutition is the closing act of 

 feeding. It is described as occurring as follows: The lips 

 are closed and the jaws are set together, then the tip, the 

 back and the base of the tongue are successively pressed 

 against the palate and thus the contents of the buccal cavity 

 are forced into the pharynx. By contraction of the muscles 

 of the pharynx in front of the food mass the peristaltic mo- 

 tion .thus inaugurated carries the bolus into the esophagus. 



