THE OPERATION FOR ROARING. 79 



2. It is aimed to complete the operation without wound- 

 ing a cartilage either in the essential operation when re- 

 moving the ventricular mucosa, during the invading incision 

 through the crico-thyroidean membrane, and later, should 

 dyspnoea occur, by inserting the laryngeal tube through 

 the existing incision instead of performing tracheotomy. 



Technic. Docile animals are readily operated upon in 

 the standing position. The animal should be confined in 

 stocks, or otherwise, in such a manner that his^head may 

 be securely held in an elevated and extended position. The 

 safety of the operator further demands that the patient 

 shall be so secured that he can neither rear nor strike. 



Resistant animals need be cast or confined upon the 

 operating table. General anaesthesia upon the recumbent 

 animal is usually unnecessary, and is only demanded in those 

 cases of unusual resistance to confinement, where the patient 

 may injure itself by its violent struggles. 



Ordinarily ample anaesthesia, whether from the stand- 

 point of surgical efficiency or of sentiment, is obtainable by 

 the use of local anaesthetics, preferably of cocaine and 

 adrenaline. 



Shave and disinfect the operative area, and inject sub- 

 cutaneously a sufficient amount of the local anaesthetic. 



Make a longitudinal incision over the larynx through the 

 skin and fascia as accurately as possible on the median 

 raphe, commencing opposite to the anterior extremity of 

 the thyroid cartilage and extending downward and back- 

 ward to the region of the first tracheal ring. Separate the 

 sterno-thyro-hyoideus muscle on the median line with the 

 scalpel blade or handle as preferred. Control the hem- 

 orrhage. If the operation is performed upon the standing 

 animal with the aid of cocaine and adrenaline, the incision 

 is virtually bloodless. 



Locate the crico-thyroidean ligament, triangular in form, 

 bounded anteriorly and on both sides by the thyroid cartilage 



