Before we can talk about firing, or pin firing, it is important to understand the idea of a counterirritation and a means of treatment for lameness. "Its [counterirritation] purpose if to convert an old chronic injury into and active form to begin an active healing process." (1) Essentially, by re-damaging an old injury, the thought is that the injury will be able to heal better the second time than the first time.
There are several types of counterirritants. They range from mild forms, such as braces, to severe forms, such a firing.
"Firing is ... [a] means of producing counterirritation; it involves piercing various parts of the horse's leg with a red-hot iron or needles, and may be used on splints, bowed tendons, osselets, rind bone, and sesamoiditis." (2) See photo for example of healed firing on horse.
As I understand the process of firing, it was a very popular treatment among race horses in the early 1900's. Even though it has fallen out of favor among horse-persons in recent years, there is still the occasional horse who shows up with the tell-tale scarring that results from firing.
1) Evans, J. Warren. Horses, 3rd Edition: A Guide to Selection, Care, and Enjoyment. Holt Paperbacks, New York, NY 2001. Page 350.
2) Evans, J. Warren. Horses, 3rd Edition: A Guide to Selection, Care, and Enjoyment. Holt Paperbacks, New York, NY 2001. Page 351.
