Local anzesthesia is the result of the action exerted upon the nerves in the area in which the agent is injected. Areas or parts may be anasthetized for operation by the injection of a local anesthetic into the area to be Op erated, or by injecting the agent along the tract of the nerve supplying the part. Local amesthe sia may also be produced by infiltration or by producing an artificial edema in the region of the operation.
Surgical Cleanliness.— The surgeon's most formidable adversary is wound infection caused by the invasion of wounds with pathogenic bacteria which sooner or later develop and multiply, and by their activity or their products set up irritation of the tissues, inflammation, suppuration and, in certain cases, general in fection of the body. Antisepsis and asepsis are two terms used to describe the method of treat ment and care of wounds, accidental or opera tive, as regards the bringing about of that con dition known as surgical cleanliness or freedom from any of the pathogenic or wound-infecting germs. Antisepsis is that process by which in fective germs are carried away and excluded from the wound, while asepsis is freedom from infective germs. In veterinary surgery asepsis will probably never obtain the same favor as antisepsis on accotmt of the natural uncleanli ness of the skin of animals, the condition of their environments and the difficulties of post operative ccmtrol. Strictly considered, howeyer, antisepsis and asepsis do not stand in opposition, but rather form mutual complements of each other; aseptic methods being preventive, anti septic curative, their association is often ad vantageous. Antisepsis is resorted to when the region of operation includes a suppurating wound, a fistula or an uker or an infected wound. Antiseptics are then employed to dis infect the seat of operation, the hands, the in struments and the dressing materials.
The aseptic method is applicable to opera tions upon healthy or infection-five tissues. Antisepsis is preferable in veterinary surgery on account of the chances of the wound, the hands and the instruments becoming infected during the operation. For disinfecting the seat of operation and the hands, chemical antiseptics are employed. Instruments, ligatures, drainage tubes and other materials used for dressing wounds are sterilized by being subjected to the action of boiling water, glycerine, heated oil or to a high degree of dry heat Some of the antiseptics most used are iodine, iodoform, potassium permanganate, car bolic acid, lysol, bichloride and biniodide of mercury, boric acid, chlorazene and dichlora mine-T.
The operator's hands are not infrequently the means of infecting wounds, and the surgeon who desires to avoid after-complications will take especial care in the disinfection of his hands. The spaces beneath the nails, the folds of skin at their base, the folds of the slcin itself and the orifices of the skin glands are all refuges for microbes, to destroy which demands the most minute precaution. In veterinary sur gery the precautions talcen extend to thoroughly cleansing the nails, washing the hands with hot water and soap and thoroughly rubbing them with 1 in 1,000 sublimate solution. The hands should be rendered aseptic and kept aseptic throughout the operation. For this reason the operator should avoid touching the skin sur rounding the point of operation, the table, the straw or any object which has not been dis infected.
The field of operation and surrounding parts should be most carefully cleansed. In all ani mals the skin is covered with extremely numer ous and varied micro-organisms among which staphylococd are particularly abundant. It is, therefore, always important to disinfect the parts. If the slun is healthy, the hair is removed with scissors or a clipper, the parts thoroughly soaped, shaved, scrubbed and washed with clean water. After beim; dried, the parts are rubbed sith ether or gasohne to remove fatty materials from the surface and are finally douched or painted with tincture of iodine. This method, however, is not applicable to all surfaces. The mucous membranes require the application of mild antiseptics and irrigation, while the foot requires paring and continued soaldng in a strong antiseptic for several hours.
Surgical Dressing of op erative or accidental, require in dressing and treatment (1) the control of hemorrhage; (2) to be placed in a position of rest, and (3) adequate provision against infection. Hemor rhage is controlled by the application of thermic agents (heat or cold), chemical agents (styp tics) and surgical methods. The surgical methods of controlling or arresting hemorrhage are represented by the tourniquet, Esmarch's bandage and the rubber cord, by compression, ligation, torsion, forcipressure and acupressure. Placing the wound in a position of rest in do mestic animals is ofttimes a difficult task. It signifies the fixation of the margins of the wound in apposition, or the fixation of the part in which the wound has occurred. The margins of the wotmd are fixed by mains of sutures and bandages, and the fixation of the part is accomplished by the confinement of the animal to as little freedom of movement as possible.