Equine Science Update
Reports from the world of  equine research.
Glue-on shoes: the next generation.
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For many years farriers and veterinary surgeons have sought alternative means of applying horse shoes for situations in which nailing-on is not practical. Glue-on shoes are available. To apply them correctly requires stringent attention to detail, making it a time-consuming, and sometimes uncertain, process.

Now Wiltshire-based farrier Andrew Poynton has designed a new hoof care system which he claims overcomes may of the difficulties encountered with other glue-on shoes. Poynton, an examiner for the Worshipful Company of Farriers, explains that the Imprint ® Hoof Care System is the culmination of over 20 years experience of working with veterinary surgeons in this field. "I had certain criteria in mind whilst developing the Imprint ® Hoof Care System.. I wanted to minimise trauma, have a perfect fit, and maximise support without compromising the natural functions of the foot. The shoe had to stay on the foot for the duration of the treatment, and had to produce a result!"

He has used the shoes on about 400 horses to date. By far the most common indication is for horses and ponies with all stages of laminitis. Other applications include angular limb deformities, flexural deformities, hoof cracks, and bruised feet.

The shoe is based on a heart-bar design. Its W-flexing bar over the heels and frog allows the shoe to be bonded to the entire lower margin of the hoof wall without preventing expansion and contraction of the hoof. The foot surface of the shoe is seated out. A flange which will contact the hoof wall extends forwards from just in front of the heels.

Poynton explains that much research has gone into choosing the correct materials for both the shoe and the glue. The revolutionary properties of the shoe are due to the thermo-plastic material used. The shoe becomes pliable at 60°C and solidifies at 35°C. It is easily warmed up in hot water, and can then be moulded to the exact requirements. The material is lightweight (the foal shoe weighs 35 grams) and hard wearing. Apparently it is also biodegradable. Water and surgical spirit do not adversely affect the methyl-methacrylate adhesive. Clear polycarbonate hospital plates are available which can be fixed in place using four self-tapping screws.

Preparation of the foot. The foot is trimmed according to usual farriery practice and the distal border of the wall is rounded off as for a grass trim. This ensures a better fit. The periople is rasped off to provide a smooth clean surface to bond to the shoe.Using a rotary burr or loop knife three or four small oval indents are cut in the hoof wall about 5mm above the distal border. Plastic from the shoe flange will be pushed into the indentations to fix it to the foot, holding the shoe firmly in place before the adhesive sets. The hoof is cleaned with surgical spirit.

Preparation of the shoe. The shoe is placed in boiling water with the ground surface uppermost. Poynton recommends resting the shoe on a used adhesive cartridge to prevent the flange collapsing when it softens. As the shoe warms up it begins to turn transparent. When the flange is completely clear, the shoe is removed from the water. Adhesive is applied to the inside surface of the flange and to the foot surface of the shoe at the heels.

Application of the shoe. The shoe is applied when soft, and it conforms to the shape of the foot. The flange is pressed onto the wall, ensuring that plastic is pushed into all the indents. While it is still soft, the frogplate is moulded to ensure frog contact. The adhesive takes 5-10 minutes to set, sealing the plastic to the horn. Once the fitting is completed, the shoe can be cooled rapidly with a freezer spray, enabling the foot to bear weight within a couple of minutes well before the adhesive sets.This is highly desirable when dealing with a painful foot condition.

Mistakes made during application can be easily corrected. "Sometimes it is necessary to reheat part of a shoe on the foot to attain a better fit." he says." A hot air gun does this job well."

A particularly useful feature is the ability to fashion extensions out of the plastic material (which is available in granule form). The extensions can then be welded onto the shoe by warming both the shoe and the extension. The Imprint ® granules can also be used for repairing hoof cracks. Notches are cut at the side of the crack to produce a jigsaw-puzzle piece outline. A small amount of adhesive is applied and then the crack is filled with melted granules.

As with other plastic shoes it is important to avoid trapping infection under the shoe.However, Poynton points out that one advantage of this system is that a hole can easily be cut inthe shoe over the affected area of foot and a buttress of thermoplastic material built up to strengthen the shoe.

To remove the shoes, the flange is rasped away and the shoe is prized from the foot with nippers, starting at the heels.

for more details see: www.imprintshoes.co.uk