Pin firing or thermocautery has therapeutic value for certain conditions in the horse. When done properly, the American Association of Equine Practitioners considers pin firing an acceptable form of therapy, writes Dr. Clyde Johnson in the "AAEP Answerline" column in the October edition of The Horse. Pin firing is a therapy that uses a small, red-hot probe to cause cauterization (burning) of tissue in horses with chronic injuries to produce an abundant, serous inflammatory process. As opposed to other inflammatory processes, such as infections or bruising, serum has little or no fibrin (clotting material) or cellular content and does not coagulate. Firing causes maximal exudation, or oozing, and minimal tissue degeneration. The flooding of serum seems to flush out any chronic irritation, and it does not displace old scar tissue. Firing is done more often in racehorses than in other performance horses, and has been used for more than a century in conditions of recurring injuries such as a splints, curbs, or chronic bowed tendons. The driving idea behind firing is that it makes chronic inflammations acute and allows them to heal. The procedure is performed under sedation and local anesthesia, and the pain inflicted is fairly short-lived and usually well-tolerated by the patient. It is important that if a veterinarian fires one leg that he pays special attention to the opposite leg. Otherwise, the horse will place excessive weight on the unaffected leg and strain that one. Many times, both of the front or hind legs are done at the same time, for it seems that an injury that occurs in one leg also will appear in its partner. Following firing, specific nursing care is necessary. This involves a strict regimen of ointments and keeping the area clean. The horse must have time off, from six months to a year, depending on the condition. A splint or curb doesn't take as much time as a bowed tendon to heal. Once the horse is able to walk comfortably on the leg, it should be allowed to do so, just as one would walk on a sprained ankle to build strength after the injured joint is able to bear weight.