472 LARYNGOTOMY. 



but subsequently a much shorter incision was found sufficient for 

 the operation, and now the opening is restricted to division of the 

 crico-thyroid membrane. Up to the stage of entering the larynx, 

 the procedure is very similar to that followed in performing ary- 

 tenoidectomy. The crico-thyroid membrane is punctured and divided 

 throughout in the middle line, from before backwards. A spring or 

 other dilator is inserted to hold the thyroid plates well apart, while the 

 mucous lining of the ventricle, seized with forceps, is incised all round 

 the margin of the opening into the pouch, and then carefully detached 

 by blunt dissection from the adjoining thyro- arytenoid muscle and 

 cartilages. The pouch, which in shape resembles the finger of a 

 glove, should be removed intact, though sometimes it is torn before 

 separation has been effected. Usually there is little haemorrhage, 

 and this can be diminished by swabbing the ventricle with solution 

 of adrenalin before incising the mucous membrane. The after- 

 treatment consists in daily disinfection of the external wound, which 

 heals in about three weeks. After closure of the outer wound, the 

 horse should be rested for a further period of six to eight weeks. 

 The chief immediate dangers of the operation are suffocation, from 

 obstructive oedema of the glottis, and pneumonia, The former, 

 which is more likely to follow excision of both pouches, can be pre- 

 vented by inserting a tube, which is kept in position for 24 hours 

 or longer if necessary. After giving satisfaction for six months to 

 a year or longer following operation, the horse may be suddenly 

 seized with acute dyspnoea, and if relief be not speedily afforded by 

 tracheotomy or other means, death ensues from suffocation. Other 

 occasional sequelae are laryngeal fistula and general enlargement of 

 the larynx. 



