58 ELEMENTS OF HIPPOLOOY. 



Strangles, or distemper, also an infectious disease, mani- 

 fests itself by catarrhal symptoms and by enlargements of the 

 salivary glands lying near the angle of the lower jaw (the parotid 

 glands). In the general case these glands suppurate and make 

 an abscess easily recognized. An animal usually has this disease 

 but once, and rarely after becoming of age. The danger from 

 strangles is in the permanent thickening of the air-passages and 

 permanent injury to the breathing apparatus in consequence. 



Poll-evil is an obstinate abscess on top of the head. It 

 results from an injury received there, which sets up an infiama- 

 mation that develops into an abscess. The muscles of the neck, 

 in the region of the poll, extend downward and backward. Pus 

 can easily burrow in between them and follow the course -of these 

 muscles. Since, from its position, such an abscess cannot readily 

 drain its pus unless artificial drainage is provided, the pus will 

 work down into the sound tissues, infecting them deeper and 

 deeper. Any abscess where natural drainage is not possible is 

 termed a fistula. Like other fistulas, poll-evil is the result of 

 neglect. 



Blind staggers, or congestion of the brain, is a brain 

 disease, similar to apoplexy. A horse affected with it will fall 

 down and struggle about in a spasmodic fashion, injuring him- 

 self in his spasm and threatening injury to any other animal near 

 him. It is a not uncommon disease, and is liable to recur at any 

 time. Relief is obtained by blood-letting. The jugular vein is 

 opened, and, after a sufficient amount of blood is drawn, is closed 

 again, leaving a scar of operation, usually not hard to find and 

 always worth looking for. 



The jugular channel is well shown in Figure 8. It is a 



groove on the lower margin of the neck. By rubbing the thumb 



briskly several times down the channel with considerable pressure 



and then pressing hard at the lower end of the channel, the 



jugular vein will be closed by the pressure. It will fill rapidly 



from above with blood and will become distended. 

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