The two middle incisions denote the part where either the fore or after portion of the foot may, perhaps, be rendered void of sensation.
The two inferior cuts suggest the situations where, probably, the parts of the foot toward which the incisions point may be made insensible.
If the horse has been operated upon before, you must expect a tedious and sanguinary business. It is then of all importance to obtain a very attentive and equally nimble man to take the sponge. Blood will follow every movement of the knife. However, with each cut you must retract the hand, and the man who has care of the sponge must quickly, surely, and forcibly cleanse the wound. When the sponge is withdrawn, for an instant, and for an instant only, is there a clear view of the part. The operator must be ready to make the most of that glimpse; for, the next moment, blood flows over the lips of the orifice and all is concealed from view. Thus we proceed, rather snipping than cutting, taking away particles instead of flakes of cellular tissue, till the nerve is exposed. Then it is fixed with the needle as before directed.
The nerve being caught, withdraw the needle, leaving the thread behind. Tie both ends of the thread together, and insert the first finger of your left hand into the loop thus formed. By gentle traction raise the nerve a little, and with the knife release its inferior attachments. Then let the man who held the sponge make pressure with all his force upon the artery and nerve above the incision. After this has been done about a minute, and by the stoppage of the circulation you may conclude the sensation to be in some degree numbed, insert the blade of the knife under that portion of the nerve which is nearest the body, and cut boldly upward.
THE LOOP RAISING THE NERVE WHILE THE KNIFE LOOSENS
ITS INFERIOR ATTACHMENTS.
A spasm mostly follows the division; but it is of short duration. Afterward dissect about one inch of the nerve from its attachments, and remove this inch from the main trunk. No sign of feeling will follow the excision when made lower down. All communication with the brain has been cut off by the previous division, and the sensorium no longer takes notice of any violence offered to that part of the body which has been isolated.
THE BEST WAY TO CLOSE THE WOUND
CONSEQUENT UPON NEUROTOMY.
Next, having sponged the part, close the wound by means of a pin forced through the lips of the orifice. Then twist a little tow round it in the form of a figure of 8. That being finished, so much of the point as protrudes is to be removed with a pair of wire nippers; a bandage is then put on; and, if both sides of the limb are to be neurotomized, the horse is turned over. All being accomplished, return the horse to the stable, but watch the pin which fastens the wound. If the incision continues dry, the pin may not be removed till six days have expired; but if the slightest appearance of pus be suspected, immediately withdraw the pin, and remove the tow, treating the part with solution of chloride of zinc, as though it were a common wound.