698 OPERATIONS. 



to the nature of the work, the season of the year during which it 

 is performed, and the danger of foreign bodies getting into the 

 windpipe via the tube, when out with hounds for several hours ; 

 permanent tracheotomy does not always answer well with hunters, 

 which, being animals of luxury, cannot with any degree of propriety 

 bear such a grievous disfigurement as the employment of the tube 

 necessitates. As horses intended for the turf, whether on the flat 

 or over a country, are required to exert their powers to the utmost 

 only at comparatively long intervals, and during short spaces of 

 time; permanent tracheotomy will generally succeed better with 

 them, than with other classes of horses, if the precaution be 

 observed of opening the tube only when they are being run, or 

 during fast training gallops. In fact, some trainers of tube-bearing 

 horses consider, as a result of their experience, that it is best not 

 to open the tube, except of course for cleaning purposes, during 

 training. Coarse-bred horses are more liable, from the use of the 

 tracheotomy tube, to inconvenient, if not dangerous, diminution 

 of the calibre of the windpipe from thickening of the mucous 

 membrane and its underlying tissues,' than thorough-breds. 



TRACHEOTOMY TUBES.— The tubes, most commonly employed 

 consist of a " shield," which remains outside the opening ; a body, 

 in the form of a cylinder, which rests in the opening of the wind- 

 pipe ; and an upper and lower branch (or arm)-, which prevents the 

 tube from falling out. 



The chief requirements in a tracheotomy tube ai'e as follows : — 



(1) It should be as light as practicable. Here, the use of aluminium 

 is self-suggestive. . Some authorities however state that aluminium 

 is objectionable on account of its irritating the tissues with which 

 it comes in contact.. I regret that I- am unable to decide this point. 



(2) It should, if of metal, as recommended by the late Mr. F. B. 

 Jones, be made of only one kind of metal, so that no galvanic 

 action be set up. (3) Evidently it should be of comparatively large 

 calibre. (4) There should exist as little difference as practicable 

 between the calibre of the opening in the windpipe and that of the 

 tube, so that efficiency may be obtained with a minimum amount 

 of damage to the windpipe. (5) The tube should be capable of 

 being-kept open or shut, as may be required. (6) It should remain 

 securely in its place without requiring to be secured by strings, 

 tapes, etc. (7) It should be easy to insert and remove. (8) It 

 should offer as little impediment as possible to the passage of air 

 to and from the air-passage above the opening. (9) Its mechanism 

 should not be liable to get out of order, or to become clogged up 

 by the action of the discharge. (10) Its component parts should 

 have no tendency to become separated, or, in such a case, to fall 



