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February/March 2006

Andrew Poynton is an examiner for the Worshipful Company of Farriers who has been treating and researching the effects of early application of the Imprint Therapeutic Shoe System. He outlines the concept from a farriery perspective, highlighting two current typical laminitic cases being treated with the system.

A LAMINITIC attack in a much valued horse or pony is highly traumatic, debilitating and potentially life threatening.

Onset is often rapid and the owner needs to know what ‘first aid’ can be immediately administered - any surface which moulds to the underside of the foot and support it, such as a sand school - not a straw stable bed - will help in the short term whilst waiting for the vet to arrive and make a full examination and diagnosis. Analgesics are administered, and
radiographs of the feet, particularly lateral views, taken on site. The horse should be box rested on a deep supportive bed, the diet reviewed and some form of frog support applied to
the feet. Beyond this the specifics of treatment begin to vary greatly, as do the results. The significance of swift farriery attention to attaining ‘ideal’ digital alignment within the hoof capsule, and subsequent foot support should not be overlooked and it may have more
significance to patient comfort and ultimate prognosis than is currently credited.

The Imprint Therapeutic Shoe

The effective component is a low melt thermoplastic shoe which is softened in hot water, then moulds to the hoof to minimise trauma, create a perfect fit and maximise support without compromising the natural functions of the foot. Unlike the application of the
conventional heart bar shoe, there is no trauma caused by hammering nails into
the foot. The shoe fit can be altered even after being applied to the foot, and it gives a much more secure and longer lasting base of support than a taped on bandage or pad. The shoe is based on a heart-bar design. Its ‘W-flexing bar’ over the heel and frog allows the shoe to be bonded to the entire lower margin of the hoof wall without impeding the expansion and
contraction of the hoof. The foot surface of the shoe is seated out. A flange (rim standing up around edge of shoe) moulded to the hoof wall extends from heel to heel. Shoe retention is good. 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 smallest shoe weighs 35 grams, it is also biodegradable. Moisture and mild contamination do not adversely affect the methyl-methacrylate adhesive.

Foot preparation

The foot is trimmed taking particular reference from the lateral radiographs to attain ideal phalangeal alignment (the position of the pastern bones and pedal bone). This often necessitates trimming a wedge of heel to realign a rotated pedal bone. Reference to the position of the hoof capsule in relation to the pedal bone is helped by the placement of
radio opaque markers such as a needle taped to the upper margin of the hoof wall at the toe, and a drawing pin positioned at the apex of the frog. Any deviation of the hoof wall at the toe is cut back at the base, to remove further leverage at the ground border and compression at the coronary border.

Non traumatic shoe application

The ground borders of the wall on the sides of the hoof are beveled. Using a high speed rotary burr or loop knife three or four small oval indents are cut in the hoof wall about 5mm above the ground border. This can be carried out when the foot is on the ground. Plastic
from the shoe flange will be pushed into these to fix it to the foot. The hoof is cleaned with surgical spirit. The shoe is placed in a container with the ground surface uppermost. Boiling
water is filled to just below the ground surface of the shoe, within two minutes it is mouldable like gum and is removed from the water. Imprint Adhesive is applied to the inside surface of the flange. The shoe is fitted 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 it is in contact with the frog. Once the fitting is completed, the shoe can be cooled rapidly using the Imprint Freezer. The foot can then bear weight, having been held up for no more than three minutes.

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