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Pinfiring proves obsolete

Posted: Tuesday, November 21, 2006

Procedure around since 500 A.D. has little science to back it up as good option for healing

by Brian D. Nielsen, Ph.D. and Jessica F. Fattal

HEARTBREAK! That is what you felt when you saw her tendon. That noticeable swelling could only mean one thing: Your horse had bowed her tendon.

Now what?

You talk to your horse-owner friends and to your veterinarian. The suggestion is that you should pinfire your horse. But should you do it? Before you go ahead with this procedure, you ought to consider a few things.

Thermocautery, or pinfiring as it is commonly known in the horse industry, has been around for ages. Conflicting ideas as to what pinfiring actually does have persisted over time. In ancient times, fire was believed to have magical properties, especially with regard to healing chronic ailments. Due to this belief, thermocautery has been commonly used as a medical procedure.

With firing, generally a hot iron is used to effectively burn, sear, or destroy tissue. While often done with a pointed iron (hence, the name "pin-fire"), it also can be done using a horizontal iron bar to affect only the skin and not to extend into the underlying tendons. Alternatively, firing can be done with the iron dipped in liquid nitrogen and then applied to the horse's leg, a procedure called freeze-firing.

The oldest surviving written record  of thermocautery for animal treatment dates back to approximately 500 A.D. It was first described by Publius Vegetius Renatus, the author of the first book on veterinary medicine, who doubted the validity of the procedure from time to time. Nonetheless, the belief has persisted that using thermocautery on tendons brings an acute healing reaction to a chronic injury, such as bowed tendons, resulting in a shortened healing time.

While many other magical practices were discarded over the years as barbaric and of no therapeutic value, firing has remained in use although many clinicians and horsemen question the practice's validity. It has been said that the continued use of firing as a treatment for chronic injuries to the equine leg is a clear case of tradition holding more sway than science.

Due to relatively few treatment options to effectively and swiftly treat lameness issues such as tendinitis, many veterinarians and trainers continue to fire horses' legs and hope that it helps. Trainers often feel they are wasting valuable time when they cannot see healing in injuries such as sprained tendons, as the healing process is extremely slow. These trainers often ask their veterinarians to fire their horses' legs in an effort to be proactive in healing the injuries.

Proponents of firing believe scar tissue created in the leg after firing has a strengthening effect on the skin and underlying tissue. This theory has been proved to be false, because the scar tissue formed in the burned skin and underlying tissues becomes thinner and weaker over time.

Few studies

A procedure that has been in use for 1,500 years should have given rise to a significant amount of data to prove its efficacy under even the most demanding statistical analyses. This has not been the case with firing. Relatively few scientific studies have been done, and the evidence available does not support the use of firing as a good option for healing injuries.

A five-year study conducted through the University of Bristol in England compared treating tendinitis with firing to treating it with rest alone. Results showed that linefiring did not appear to have an effect on the healing process of the tendon.

In addition, clinical cases of pinfiring in which the cautery iron was extended into the tendon itself caused permanent changes in tendon structure. These changes were confined to the tracks of the firing pin.

However, no evidence was found that linefiring or pinfiring of the skin had any marked effect on tendon healing, with the exception that in a few cases it appeared to delay the overall healing process.

The conclusions from this study made clear that healing sprained tendons is a lengthy process, no matter what the treatment, and the time necessary to heal often extends beyond 14 months.

Treatment of tendon injuries by firing also did not improve the rate at which the horses regained pre-injury soundness and normality of their gaits. Based on the lack of beneficial evidence brought forth by firing legs of horses suffering from tendinitis, the researchers concluded firing was not useful or justifiable.

Also giving rise to doubt about the justifiable use of firing is that many veterinary associations across the globe have decided to oppose the use of thermocautery as a treatment for equine lameness. The Australian Veterinary Association in its May 2002 position on thermocautery of horses states that it recognizes the rights of veterinary practitioners to choose the method and type of treatment for their individual cases. However, they encourage members to consider whether the use of thermocautery can be justified in the absence of any scientific evidence for its efficacy.

The Royal College of Veterinary Surgeons in England declared a similar statement in their Mutilations Report in 1987. However, the American Veterinary Medical Association has upheld its acceptance of veterinarians using firing in horses and presently described the use of thermocautery or pinfiring as having therapeutic value for horses under certain conditions.

Besides the formal discourse among the scientific and veterinary communities as to the efficacy of firing, one must consider some common-sense knowledge when considering the use of thermocautery.

One popular argument for those opposing the use of firing is if it is good for promoting healing in tendon injuries, why is it not commonly used to treat tendon injuries in humans? Could it be the pain involved, the negative connotations involved with being so desperate for a treatment as to inflict unnecessary burns to the skin, or simply because humans recognize that rest alone may be the most conservative and beneficial route for healing?

Consider other options

Suggesting a commonly performed practice should be discontinued will be met with scorn by some individuals. However, horse owners are encouraged to give strong thought to whether they should have their horse fired to encourage healing of a chronic injury. Evidence from scientific, controlled studies generally indicates that it does not promote healing any better than just giving the injured animal time off from exercise and, in some cases, it actually can delay healing. Without strong scientific evidence to show it aids in healing, one should question whether putting the animal through the pain that typically accompanies this procedure is worthwhile.

While veterinary associations in other countries have banned the practice, firing still is allowed in the United States, though many veterinarians refuse to do it. Even if it is suggested as a treatment by your veterinarian, it is important to weigh all the issues involved and decide if it is truly in the best interest of your horse.

One question you ought to ask before going ahead with the procedure is whether you would allow your doctor to do it to you. If the answer is no, then you ought to consider whether you should allow your veterinarian to do it to your horse.

Brian Nielsen, Ph.D., is associate professor of equine exercise physiology and nutrition at Michigan State University, and Jessica F. Fattal is a veterinary student at Michigan State.