A HORSE'S LEG WITH TWO SNIPS UPON IT, c c, OUT OF WHICH HANG THE TWO KNOTTED ENDS OF A SETON, D D.
Periosteotomy is not very highly esteemed by the vast majority of practitioners. It is, however, sometimes very successful. A horse is thrown, being dead lame; the animal gets up from the hands of the surgeon and trots sound. It is difficult, however, to predicate the quadruped on which it will thus act. Certainly the operation is best adapted to young horses; but even to all of these it will not prove beneficial. It is therefore looked upon as a surgical experiment, quite as apt to disappoint as to please. The seton, moreover, is disposed to cause the edges of the holes through which it passes to indurate. A blemish which it takes some months to eradicate is the consequence; and this, added to the expense attendant upon treatment, is not apt to prove pleasing to horse proprietors, especially when the operation altogether fails.
A modification of periosteotomy might perhaps be tried. Omit the seton altogether; make an inferior snip with the scissors; introduce a sharp-pointed needle, and cut a channel. Then insert a probe-pointed bistoury, and incise the tumor. If periosteotomy were to prove successful, it probably would be so in this shape. The author has seen small benefit result from the after-use of the seton, and by operating in the manner proposed all the subsequent blemish would be avoided. The cut would soon heal and leave no scar behind: thus the grand objection to the performance of periosteotomy, as it now stands, would be removed.
The motive for the above proposal is to spare the suffering of the animal. If the hair is cut short previously, and pressure made above the snip of the scissors, the wound need occasion little pain. A sharp point cutting its way through the cellular tissue would not cause one tithe of the agony which follows the use of a blunt instrument necessarily tearing, stretching, and breaking a passage through a living body. Cartilage or bone in a state of health has small sensibility. The employment of the knife would therefore provoke no struggle, while all the after-torture of a seton applied directly to the surface of a wound would be avoided.
Perhaps it would be best to bind a broad tape, with a cork under it and upon the vessels, round the leg before the operation, thereby pressing on the nerve and cutting off the supply of blood. This would probably deprive the leg of all sensation. The most severe part of this method of periosteotomy would be the after-consequences. The incised tumor would inflame; the vacant channel would have to unite. The one would occasion agony, the other be probably attended with violent itching. The limb, therefore, should be bandaged, even though a wound upon the horse's body does not do so well when covered up. The bandage, however, will prevent the animal from injuring the sore leg with the opposite shoe, which a horse may be provoked to attempt by that irritation which attends the healing process.
OPERATIONS—NEUROTOMY.
Neurotomy is the division of the nerve which supplies the hoof of the fore leg with sensation. The foot of the horse being moved through tendons by muscles from above, and having in itself no muscular power, obviously has no occasion for a motor nerve. Consequently the nerve running to the foot is wholly sentient. It is the means of communication through which pain or pleasure is transmitted from the hoof to the brain.
To take away a portion of this nerve is evidently to separate the medium of such communication. Feeling can no more travel along a divided nerve than electricity can along a broken wire. The knowledge of this fact has led to a portion of the nerve being excised; and the doing of this has been named neurotomy.
A nerve is a very compound structure. It is composed of numerous fine filaments or small threads bound together by a cellular sheath called neurilema. Healthy nerve feels firm, and has a brilliant white appearance; unhealthy nerve is of a yellowish tint, and is of a less solid texture.