FISTULOUS WITHERS. 
775 
mal lias become extremely vicious from the repeated injections of 
caustics, that it becomes necessary to confine the animal; even 
then it is often impossible to operate properly without first 
administering- chloroform. The hair and mane over the tumor 
having been removed by clipping, or, better still, sheared, the 
parts are thoroughly washed with warm carbolized water, in 
which all the instruments for the operation have been im¬ 
mersed ; a straight incision extending from nearly the summit of 
the dorsal spines, is made through the centre of the tumor and is 
carried downward through the muscular tissues to near the 
border of the cartilage of prolongation of the scapula, if found 
necessary to do so. This insures good free drainage for the entire 
diseased mass. Bleeding vessels can be easily closed by torsion 
with the artery forceps after making the main incision. The 
fistulous canals are now sought for with the index finger of the 
left hand and as found are to be laid open their entire length 
with a probe-pointed bistoury, or, better still, a long-bladed hook¬ 
shaped knife made expressly for the purpose. After being thus 
laid open, the fistulous tracts are thoroughly curetted, which re¬ 
moves all remaining false membranes. Should any of the dorsal 
spines be found to be diseased they can be readily cleaned off with 
the bone forceps or periostotome. No muscular or other sound 
tissue is to be removed en masse , as this leaves a blemish and 
further exposes the dorsal spines to further injuries. Where 
both sides are diseased, it is best to select for the incision that 
side on which the enlargement is greatest, and from this pass the 
seton through to the opposite side. Sometimes but one of these 
will be required ; then again, where the sinuses run forward and 
downward toward the cervical vertebrae, as many as two or three 
may be needed to give proper drainage to the cavities. 
The object of this operation is to change into one healthy 
sore what was previously a mass of suppurating flesh, permeated 
by many fistulous canals. After thorough irrigation of the cav¬ 
ity with carbolized water, a pledget of oakum or absorbent cotton 
is gently packed into it, the edges of the wound are now brought 
together by a couple of interrupted sutures to hold the pledget 
