198 
TRACHEOTOMY. 
made larger than intended, in consequence of the animal suddenly 
stretching the neck, though in phlegmatic horses, and those suffering 
from severe illness or dyspnoea, the precaution is not so necessary. 
The skin being divided, and any bleeding vessels ligatured, the panni- 
culus is cut through, and the pairs of muscles lying below it are 
separated in the middle line, the proper point being indicated by its 
lighter colour (connective tissue). Where the middle line is exactly 
encountered scarcely any bleeding results, and the trachea is exposed. 
In thin horses with slightly developed necks this procedure is very 
simple; but in fat horses with thick necks there may be a little more 
difficulty, though no danger. The edges of the wound are held apart 
with a pair of broad hooks, with the fingers of the left hand, or with 
a retractor. Up to this point the procedure is 
the same in both methods. 
In the operation without removal of tissue, 
the trachea is now divided either perpen¬ 
dicularly through the third and fourth rings, 
or a horizontal cut made in the intervening 
ligament; or a vertical incision providing 
more room is made by thrusting the knife, 
with the cutting edge upwards, into the 
trachea at the lower edge of the wound, and 
carrying the cut upwards through three or 
four tracheal rings (fig. 88, b). The hooks 
are now introduced into the trachea, or the 
index and middle fingers of the left hand 
hold the edges of the wound apart, and the 
canula is inserted. The trachea in the horse 
Fig. 89.—Barthelemy’s canula. 
being of considerable size, little difficulty is met with, even when dealing 
with the firm textures of old subjects. 
When the canula is to be worn for a considerable period, and must, 
therefore, be removed every few days to be cleaned, a square, oval, or 
occasionally a round piece is excised from the anterior wall of the air- 
tube. Viborg, who first recommended the square , opening (fig. 88, a), 
directs the knife to be inserted between two cartilages, and a horizontal 
cut made about f inch in length. This cut should extend an equal 
distance on either side of the middle line. From each of its ends a 
vertical cut is next made downwards, and the piece of cartilage which 
now hangs by the intercartilaginous band below is grasped with dissect¬ 
ing forceps and cut away, care being taken to prevent its falling into the 
trachea. The canula is then placed in position. Lafosse, Brogniez, and 
Gunther have expressed themselves in favour of the oval opening, which 
may be produced by first dividing the intercartilaginous ligament and 
