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 thermoplastic material used. The shoe becomes
pliable at 60ºC and solidifies at 35ºC. 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 these to help fix it to the foot. 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 frog
plate
is moulded to ensure frog contact. The adhesive
takes 3-5 minutes to set. Once the fitting is completed, the shoe can be
cooled rapidly with a freezer spray.
Poynton says that compared with other plastic shoes it is easy to apply, and
is very forgiving. 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 in the 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 pincers, starting at the heels.
