VARIETIES, SYMPTOMS, AND COURSE OF THE DISEASE. 101 



tion with the outer air is rendered patent, this tube being 

 retained in its position as long as needful. 



In performing the operation, it is rarely necessary to cast 

 the animal, or even place him under restraint. It is readily 

 enough accomplished by simply elevating the head, which, 

 being straightened upon the cervical articulation, so places 

 the structures on the inferior surface of the neck in a state of 

 tension. The operator, selecting that portion of the trachea 

 which is least covered with muscular or other tissue, which is 

 about one-third of its length from the angle of the jaw, nearly 

 where the subscapulo-hyoideus passes from beneath the 

 diverging sterno-maxillaris muscles, makes an incision from 

 one to two inches in length directly on the trachea, following 

 the course of the tube ; he may either pass the point of his 

 scalpel straight through the wall of the tube, dividing trans- 

 versely two or more of its rings, or he may pass a strong 

 needle, armed with a stout ligature, through one of the rings, 

 and with the knife excise a circular portion, probably of one 

 whole ring and portions of other two, the one above and the 

 other below, having the orifice a little smaller than the tube he 

 intends to insert. 



Either of these methods Avill succeed ; but if the first be 

 adopted, the tube is grasped much tighter, a little care being 

 exercised when it is passed to avoid carrying with it the edges 

 of the trachea. 



The tube must be allowed to remain in its situation until 

 the difficulty in breathing — the cause for its insertion — has 

 been removed. This is easily ascertained by at any time 

 placing the hand over the orifice, with or without the removal 

 of the inserted instrument. On being finally removed, the 

 wound may be left to close without further interference, or in 

 some instances two or three sutures may be passed through 

 the superficial edges. 



From the fact that during a few years of the earlier period 

 of their lives a very large percentage of horses are sufferers 

 from strangles, as also believing in the probability that 

 animals once affected have conferred upon them an immunity 

 from further attacks, many breeders and owners of horses 

 show little disposition to adopt measures to prevent its occur- 

 rence or limit its dissemination. However, as it does not 



