HOW TO GLUE ON THERAPEUTIC SHOES

Stephen E. O'Grady, BVSc, MRCVS

Edgar Watson, CJF


Reprinted with permission from the American Association of Equine Practitioners.
Original printed in the 1999 AAEP convention proceedings

 

Introduction

Attaching a shoe to a compromised equine hoof wall has presented a challenge to both veterinarians and farriers. The discomfort or trauma caused by the concussion of driving a nail may prohibit the conventional use of horseshoe nails in many foot injuries. Some conditions that may warrant a non-nailing (alternative) technique are acute or chronic laminitis, extensive hoof wall separations (white line disease), resections or avulsions, third phalanx fractures and severely damaged heels resulting from the long toe - underrun heel syndrome. A polymethylmethacrylatea (composite) was introduced in 1988 for the repair of hoof wall loss and cracks. This acrylic has been modified to provide flexibility, and at the same time, adheres well to hoof walls.1 More recently; this material has been used with excellent results to attach therapeutic shoes (or any shoes) to the hoof. This report describes a method that utilizes the ground surface and perimeter of the foot and differs from other described methods, which have used only the outer surface of the hoof wall. Use of the ground surface and hoof perimeter is especially advantageous if there is significant hoof wall loss. Non-nailing alternatives are not meant to replace conventional horseshoeing but are a temporary measure that can be used to attach a shoe while treating an underlying hoof problem.

Method

The procedure is relatively easy to master, but strict attention must be paid to preparation of the hoof. Sedation of the animal is rarely necessary. Local anesthesia can be used if the horse is unable to stand on the opposite limb as in the case of severe laminitis. The hoof is leveled and the heels are moved back toward the widest part of the frog if possible using a rasp. Any adjustments in hoof angle or medial - lateral balance are made at this time. All loose ex-foliating sole is removed down to solid, live sole with a hoof knife. Any separations or fissures in the sole wall junction (white line) are explored, using a bone curette and/or a Dremel toolb. If these tracts can't be removed or go too deep, they are packed with a medicated puttyc with a tail leading to the outside for drainage if necessary to prevent a possible abscess. Aluminum shoes have be used predominately because they are light and easy to work with but steel shoes can be used if desired. The shoes are fitted to the foot at this time. Bar shoes (aluminum or steel) can be used if appropriate for the condition being treated. The shoes are fit to extend slightly beyond the hoof wall from the widest part of the hoof to the heel. This provides a base for the bead of composite that will be smoothed out onto the hoof wall. Quarter clips are recommended to keep the shoe in place when it is seated in the composite. The bearing surface of the shoe is sanded and set aside to remain clean. The final preparation of the ground surface of the foot and one inch up the outer hoof wall is accomplished by sanding with a drum sander attached to a Dremel tool. The prepared surface is washed with acetone or denatured alcohol, dried with a heat gun and placed in a clean cloth boot.2 A 4-inch by 4-inch square of fiberglass is pulled apart so that the strands resemble "angel hair" and is mixed with the composite. This makes the Equilox® firmer and easier to mold, adds structural strength to the composite and enhances the flexibility of the bond between the shoe and the hoof wall. Using gloves, a layer of the plain composite is applied to the area of the hoof to be bonded, working it into the surface. This will improve the contact area to be bonded. The combined composite and fiberglass is then picked up and molded (rolled) into a tubular structure. One roll is placed on either side of the prepared foot starting at the quarter and extending to the heel. With hoof wall loss, a smaller roll is placed on the available ground surface. The fitted shoe is then placed on the hoof and pressed down firmly into the desired position. A small amount of Equilox® will bulge out on either side of the shoe forming a bead. Using a finger, this bead is spread on the outer hoof wall (forming a lip) and on the inner sole (next to the shoe). The material on the solar surface is molded to the existing concavity of the sole where it will adhere and strengthen the existing sole.

The foot is covered with plastic wrap, which is held in place with a co-adhesived bandage. Molding the material over the sole can be continued through the covered foot. The foot is held up until the composite has hardened (usually 1-2 min). Any composite material covering the frog is removed and the material on the perimeter of the hoof wall is shaped and smoothed with a rasp. It is easy to raise the heels or adjust the foot angle in any direction by just molding the tubular structure of the composite thicker or thinner to achieve the desired effect. .

To remove the shoe, hoof nippers are carefully placed between the shoe and the hoof. One or two cuts are made through the glue at the heel and the shoes are peeled forward. The glue-on procedure can be repeated at regular intervals as necessary.

Results

We have shod 50 horses in this manner in our combined practices. These have included horses suffering from chronic laminitis, hoof wall separations, a third phalanx fracture and horses with lameness due to chronic heel soreness (long toe - underrun heel). Horses with laminitis and severe hoof wall loss showed immediate improvement after the procedure. Horses with lameness due to heel sensitivity (bruising) became sound and were able to resume work. The bonding capabilities of this composite appeared superior to previous methods (products) used.

Discussion

Glue-on technology has been available since 1986.The techniques have employed the outer hoof wall by using a cuff or plastic tabs for attachment. These have proved cumbersome and unpredictable, but the technology continues to be refined, as new products become available. The method described here uses the ground surface of the hoof with the shoe glued directly to the bottom of the foot. Moreover it uses a product that was not originally developed for this purpose, but which appears to have superior ability to adhere to the hoof. This method can be used providing there is sufficient ground surface on the lateral and medial side of the hoof. In the case of the laminitic horse, using radiographic guidance, the heels can be raised or lowered to create a more parallel relationship between the third phalanx and the ground. This is accomplished by the varying amount of composite used to create the tubular structure thereby changing the angle of the shoe relative to the foot. This allows weight bearing to be localized to the heels and relieves pressure from the lamina in the toe area. Hoof wall separations have historically been treated by resection and acrylic repair so that nails can be placed in the affected area to attach the shoe. However, the disease process often will continue under the repair, prolonging the time required for the hoof wall to grow out. By gluing the shoes to the ground surface of the foot, the resected area can be left open to be debrided and medicated regularly. With a third phalanx fracture, an aluminum bar shoe is used and a continuous rim can be formed around the entire perimeter of the hoof using the composite that is pressed out when the shoe is set in place. This provides excellent stabilization of the fracture without the trauma of nailing. Horses with bruised heels resulting from the long toe underrun heel conformation improve immediately. It is our contention that the discomfort associated with these weak heels is caused by trauma, heel movement against the shoe and lack of sufficient hoof wall in this area. This movement causes continual and excessive wear at the heels leading to further pain and little chance for regrowth. A deep "trough" cut in the heel of the shoe further attests to this movement. It is our feeling, that by attaching the shoe directly to the heel, movement is stopped and the heels are stabilized. The interface provided by the composite between the heel of the foot and shoe may also reduce concussion exerted on the heels. This may eliminate pain and allow the heels to strengthen and regrow. Flat feet will invariably accompany the long toe underrun heel conformation. Composite spread over the sole during the procedure adheres to it and forms a "false" sole that will provide additional protection.

A drawback of this method is that it can be expensive and time consuming, and success depends on proper hoof wall preparation and composite application.2. However, it offers an improved method to attach horseshoes to the ground surface of the equine hoof when a non-nailing alternative is indicated. Moreover it requires no special shoes and is accomplished using ordinary shoes and composite.

References:
1. Moyer W, Sigafoos R. Equine hoof wall repair. Trenton: Veterinary Learning Systems, 1993; 6.
2. Moyer W, Sigafoos R. Preliminary experience and uses of composite hoof wall repair, in Proceedings. 37th Annu Conv Am Assoc Equine Practnr 1991.

Footnotes:
a. Equilox® - Equilox Int'l 110 NE 2nd Street, Pine Island, MN 55963
b. Dremel® Dremel Tool Co. Emerson Electric, 4915 21st., Racine, WI 53401
c. Keratex® putty - Advance Equine P.O. Box 54 Versailles, KY 40383
d. Vetwrap® - 3M Animal Care Products St. Paul, MN 44144-1000

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