186 
DISEASES OF THE LARYNX AND TRACHEA. 
with a specially-constructed instrument in the form of a hooked knife. 
Thickenings and tumours on the vocal cords can be excised. The 
horse should be cast, and, if restless, amesthetised. The hair over the 
larynx is shaved, and a cut made through the skin in the middle line, 
from the thyroid to below the 1st, 2nd, or 3rd tracheal rings. After 
ligaturing any bleeding skin vessels, the second cut is made, dividing 
the subscapulo-hyoideus and the sterno-thyro-hyoideus exactly in the 
middle line. This exposes the cricoid cartilage 
and trachea, which are then incised. The edges 
of the wound are held apart with broad hooks 
or retractors. Where a tampon-canula (fig. 81) 
is available, it should be inserted in the trachea 
to prevent danger of suffocation from entrance of 
blood. The finger is introduced into the larynx, 
the vocal cords examined, and either of them 
exhibiting the above-described changes is excised 
with scissors. The cord is previously fixed by 
grasping it with a torsion or clamp forceps; or, 
in their absence, it is made tense by a ligature 
passed with a curved needle over its lower anterior 
end. Bleeding is slight, and is of no importance 
if a tampon-canula is inserted. Should it occur, 
it can be checked by plugging the larynx. The 
tampon-canula and tampons can be removed 
next day, but, for security, the canula is better 
left in position for some days, especially when 
the animal is not under the eye of the operator. 
Serious swelling of the mucous membrane and 
dyspnoea occasionally occur, but are rare. 
When tumours are within the laryngeal cavity, 
their size and character are ascertained by open¬ 
ing the larynx, and their removal, especially if 
pedunculated, is effected with the scissors and 
the “ ecraseur.” In dealing with new growths removal must be com- • 
plete; Paquelin’s cautery, in certain circumstances, does good service, 
and also checks bleeding. Where marked dyspnoea exists, or occurs 
periodically, tracheotomy must either be performed before casting the 
horse, and a canula inserted ; or the instruments must be in readiness, 
so that, in case of need, a tube can be inserted. In the treatment of 
perilaryngitis chronica fibrosa, or of new growths with broad bases in the 
larynx, tracheotomy below the growth is the only means of removing 
dyspnoea. 
Fig. 81.—Tampon-canula ov 
Trendelenberg-canula. 
