I20 Veterinary Medicine. 



is always available in threatened suffocation from obstruction to 

 the passage of air in the nostrils and throat. 



Different methods of opening the windpipe have been resorted 

 to. One IS by means of a cannula and trochar at least three-fourths 

 of an inch in diameter and about five inches long and with two 

 large oval orifices in the middle of the cannula, and on opposite 

 sides. This is made to transfix the windpipe with its investing 

 skin and muscles from side to side in the middle of the neck, care 

 being taken to pass it in the interval between two adjacent carti- 

 laginous rings. The trochar is now withdrawn and the orifice 

 in the cannula corresponding to the interior of the windpipe, the 

 animal is enabled to breath freely through the tube. The can- 

 nula has only then to be secured in its place by a tape carried round 

 the neck. 



The more common plan is by introducing a tube through a circu- 

 lar opening made in the trachea. For this operation are needed, 

 sissors, knife with a thin narrow blade, needle and thread, and 

 tracheotomy tube. The common tube is about an inch in di- 

 ameter, four to five inches long bent upon itself so as to fit into 

 the trachea, and furnished with a flat shield to slits in which cords 

 may be attached to fix it in its place. A second variety is only 

 long enough to reach into the windpipe. It is provided with a 

 flattened shield externally and from its inner extremity projects 

 downwards at right angles a plate curvfed so as to adapt it to the 

 form of the interior of the trachea. There is an additional plate, 

 to fit into the upper part of the tube, provided with two lips pro- 

 jecting from it at right angles ; the outer lip is screwed to the 

 shield after the tube has been introduced into the wind pipe and 

 the inner lip is thus fixed inside the ring of the trachea, immedi- 

 ately above the opening and effectually prevents any displacement 

 of the tube. 



In operating the animal is kept standing with the head as nearly 

 as possible in the natural position. The hair is removed from the 

 skin beneath the windpipe between the middle and upper thirds 

 of the neck. The skin having been rendered tense, (without dis- 

 placement) by the fingers and thumb of the left hand, an incision 

 is made in the median line from above downwards, for about two 

 inches and js carried through the muscles so as to expose two 

 rings of the trachea. The needle and thread are passed through 



