First off, this is long, I’ve copied it from the website. It’s the FIRST and ONLY article I’ve seen that indicates that navicular MAY NOT be the kiss of death. With a recently diagnosed horse who is an absolute cadillac, I’m going to hang on to the hope written in here and persevere.
Navicular Syndrome: Shoeing Methods
© Tom Stovall, CJF
Navicular Syndrome is any lameness in the rear third of a front foot which will block out with a posterior digital nerve block, usually both fronts are involved, although this is sometimes not evident until one is blocked.
All methods of shoeing for NS are palliative in nature. A farrier can’t cure or correct anything, he can only relieve the symptoms to some degree. One hears the term “corrective shoeing” used in the treatment of NS horses however, “corrective” is a misnomer: no method of shoeing will “correct” the condition.
Shoeing for NS must meet several criteria if it is to be successful: it must decrease pressure on the navicular bone from the deep digital flexor tendon, it must enhance breakover, and it must protect the rear third of the foot from environmental pressure.
The classic method of shoeing the NS horse is called, “Stand 'em up and turn 'em over.” This means that the farrier will do whatever he can to decrease the length of the phalangeal lever and to increase phalangeal angulation.
Increased angulation can be accomplished by several methods: cutting the toe, mechanically raising the heels, and setting the shoe under. Since the farrier is unable to grow hoof, raising the heels is sometimes accomplished through the use of wedge pad(s) and various types of non-traction calks; e.g., roll calks, wedge calks, etc.
Why is increased phalangeal angulation a Good Thing? Because this relieves the pressure exerted upon the navicular bone by the deep flexor tendon which uses the navicular bone as a fulcrum before it inserts into P3 (coffin bone, third phalanx). The navicular bone comprises the posterior portion of the coffin (distal interphalangeal, DIJ) joint and is subjected to compression by the DDFT every time the foot is turned over. Increased angulation relieves pressure from the DDFT, but how is turnover enhanced?
Turnover is enhanced, in the main, by shortening the phalangeal lever.
The lever is shortened, primarily, by cutting off as much toe as possible.
Next, by several means: through choice of configuration of shoe materials; i.e., the use of half-rounds, aluminum (which becomes a de-facto half-round with wear) and hot-rasping the ground surface of the toe of a conventional shoe. Finally, and most important from the standpoint of enhanced turnover, the shoe must be set under so that an imaginary line from the front of the fetlock, bisecting the toe, to the ground, is as short as possible.
By setting the shoe under, turnover is enhanced, and pressure on the DDFT is reduced as a direct result. The obvious limiting factor to setting the shoe under is the white line; however, the shoe can be set under to the posterior edge of the white line if necessary. The toe should be “chopped off” (cut off perpendicular to the ground) rather than “feathered” to the coronary band in an effort to make the foot look “pretty”. Excessive rasping, aka, “feathering the toe”, destroys the structural integrity of the hoof.
The easiest method of protecting the rear third of the foot is the use of a bar shoe. Underslung, low-heeled horses respond best to conventional (track-style) egg bars, probably because, being set under, the increased support relieves pressure exerted by the DDFT. Upright horses seem to respond better to the more circular style of egg bars or straight bars.
All styles may be configured with a “frog cradle” which protects the frog from environmental pressure; however, if moisture or weak heels is not a problem, it’s sometimes more efficient to use a wedge pad or bar wedge pad to accomplish the same result.
Many racetrackers have heard the old wives’ tale: “A horse can’t run in bar shoes”. The truth of the matter is that any horse that needs bar shoes, can’t run with out them.
The aforementioned methods of farriery may be used individually or in combination. A horse with minor symptoms might be shod with half-rounds slightly set under; a horse with serious problems, with aluminum egg bars set under as much as possible and three degree bar wedge pads.
Navicular problems range in severity from a slight bruise to the navicular bursa to a fractured navicular bone. They are all treated, mechanically, in much the same manner with the exception being that DIJ problems are sometimes palliated by means of a pressure bar which applies general (as opposed to apexal) pressure on the frog.
Navicular Syndrome is no longer the Kiss of Death it once was. Due to farrier/veterinary cooperation resulting in a greatly increased body of knowledge relative to the diagnosis and treatment of this syndrome, horses which would have been euthanized 20 years ago are now dying of old age after leading full, active lives.
Tom Stovall is an American Farriers Association Certified Journeyman Farrier since 1983, a Member of the Texas Professional Farriers Association, and a Member of the Artists-Blacksmiths Association of North America. Thanks to him for his permission to post this article.
We just happen to have a level asphalt road that I jog them for soundness on – on the dirt/grass he jogs 100% sound. Go figure. I’d just rather fix it now, than once he is unrepairable.