Henry Heymering, CJF, RMF
|Published in the May 1999 Issue of Anvil Magazine
February, 28 - March 2, 1999 • Lexington, Kentucky
Year after year, the Bluegrass Laminitis Symposium comes up with the latest and most thought-provoking lectures. This year, as always, there was much to learn and think about. Following is a synopsis of the topics covered.
Ric Redden, DVM, spoke about the Do’s & Don’ts of the 4-Point System. This is how he describes the 4-Point Trim: “The hoof capsule is trimmed to utilize maximum heel length. The toe is trimmed to offer breakover approximately 3/4” in front of the true apex of the frog. The quarters are slightly lowered and given a smooth, uniform radius. The calloused surface of the frog, bars and sole are left undisturbed.”
Dr. Redden explained that the 4-Point Trim is not for every horse, but is particularly useful for horses with long, stretched-out toes, and underrun heels. Once the foot is back in shape, it may no longer be necessary to continue with the 4-Point Trim. He stressed that understanding of the hoof, and knowing what is inside of it, is paramount to success with the 4-Point method. Radiographs should be used whenever possible. He said that learning occurs in your hands you learn by doing.
A few of the helpful tidbits he mentioned were: black hoof show-coatings
destroy hoof wall; a line through the coronet on the hind feet should intersect
the front legs at the knees; when it comes to heels, “speed kills” and
“moisture kills” - both are very damaging to heels; the “ventral angle” (the
angle that the bottom of the coffin bone makes with the ground) is very important
- horses with a negative ventral coffin bone angle in the hind feet are typically
sore around the croup muscles; P2 becomes more upright just by bringing the
breakover point back.
Christopher Johnston, DVM, PhD, spoke about Impact in the Athletic Horse; about Heel Expansion; and also about Objective Biomechanical Testing of Horseshoes. Dr. Johnston finds that a softer surface may absorb as much as 90% of the impact forces. In his laboratory studies, as much as 80% of the impact force on the limb is absorbed in the hoof, before it reaches P2.
Dr. Johnston outlined three possible explanations for heel expansion of the hoof under load: the frog pressure theory, the depression theory, and the hemodynamic theory. Every one of these may play a part. Using a thin wire attached to the heels and a potentiometer, Dr. Johnston found about 1 mm (1/24 of an inch) expansion at the heels under load, followed by contraction of the heels as the hoof approached breakover during motion. Shoes decreased the amount of expansion and contraction.
Al Kane, DVM, MPVM, PhD, spoke about his research on Hoof Imbalance Associated
with Catastrophic Injury of Thoroughbred Racehorses. Dr. Kane first gave
an overview of the many methods of measuring hoof balance static,
dynamic, and result-oriented. He spoke about methods of symmetry, pastern
angle, Duckett’s Dot, feral horse studies, Birdsall’s coronary contour, and
the photographic study by Staples and Negri to name a few. Dr. Kane
has come up with a method of objective assessment of hoof balance similar
to that of Staples and Negri it is the computerized digital image
analysis to measure the shape and symmetry of the hoof. It is this method
of assessment that he used in his study of the hoof balance of race horses.
Dr. Kane’s research showed that race horses were less likely to have a
catastrophic musculoskeletal injury if their hooves were slightly broader
from the frog to the lateral wall than were those horses whose hooves had
the same distance from the lateral wall to the frog as from the medial wall
to the frog. Fatal suspensory apparatus failure was much more likely to occur
in horses whose hooves had a much lower angle to their heels compared to
the toe (under-run heels). See figures 1 & 2.
Emil Carre´, CJF, RJF, spoke about the Farrier’s Role in the Treatment of Equine Lameness. Mr. Carre´ quoted veterinarian Jerry Black as saying, “The farrier is the most important person in maintaining the long-term soundness of the horse.” Mr. Carre´ spoke about his experience working as the farrier for a veterinary clinic the last 12 years. He noted that veterinarians get little, if any, formal training in farriery, so it is important for both professionals, farriers and veterinarians, to work together. He cautioned farriers against following fad and fashion instead of common sense, and also be sure to get a veterinary diagnosis before attempting treatments.
“Interdependence is the concept of “we”. We can combine our talents and abilities to create something greater together. When we truly understand that we need the best thinking of other people, combined with our own, to achieve the best possible results, then and only then is when we have transcended the singular notion of “I”. We are then ready to move into the only truly mature concept of problem solving, the interdependent relationship.
How do we achieve these lofty goals? My suggestion is seek out and meet people with similar goals. Look for people of like minds who want to work together, and associate yourself with the state and national associations that represent your professiona. If you are a farrier interested in lameness work, identify the veterinarians in your area willing to work with farriers, and who share your feelings. If you are a vet, do the same. You might even go so far as to create a network of people in your area, in whom you have faith, so you can refer work when the need arises. This kind of support mechanism can and often will make for greater benefits for all, and can lead to a positive monetary impact on your practice. True professionals realize the potential benefits of an interchange of ideas, and the potential benefit to horses of the acceptance of these principles.”
Frank Nickels, DVM, MS, Dip ACVS, spoke about Laminitis: Complications of Treatment, What Else Can Go Wrong. Dr. Nickels spoke primarily about the treatment of severe rotation (penetration of the solar corium through the horny sole) by tenotomy of the DDF tendon. His early attempts at this treatment often resulted in a partial luxation of the coffin joint, causing caudal heel pain and arthritis of the coffin joint, as well as fibrosis and sometimes contracture of the deep digital flexor tendon. He has found that by using support bandages, stall rest, and controlled exercise for a period of eight weeks after surgery, plus the hasty resolution of hoof infections, using systemic antibiotics if necessary, he has been able to largely avoid these complications. He finds a favorable outcome in approximately 60% of these cases of severe founder.
Sandy Loree, CJF, spoke about Using Sole Support to treat Laminitis. “If you unload it, it will heal,” are his watchwords. He does this by use of a sole pad that is thicker than the shoe, packed with dental impression materialthus having the weight of the horse rest on the sole, not the wall. He finds this is tremendously effective for treating any condition that results from a previous overload on the wall, such as hoof cracks or founder. For acute laminitis, Mr. Loree suggests immediately transferring the load to the sole so as to prevent rotation from ever occurring.
“Laminitis is really a simple condition. In the foundered hoof, the laminae and other tissues are injured as the hoof wass is lifted away from the coffin bone. When we consider that this is similar to a human loosing a thumb nail, a displaced hoof wall should not be a permanent disability nor a death sentence. Laminitis is simple to manage if it is treated as an overload condition and the weight bearing load is removed early. By unloading the wall and laminae, the complications associated with laminitis are minimized or nonexixtent. The horse can live and continue to perform.
The subject of this presentation is Laminitis, but it is important to note that other ailments involving the hoof wall or laminae can be effectively managed by unlading the hoof wass. Hoof wall cracks, flares, dished profile, extended whiteline, and crushed heels are all symptoms of tissue overload. Reduce the load from the hoof wall and laminae and these problems go away. A reduced load on the wall can enable horses with then, weak hoof walls to enjoy a productive performance life. A sole support system can be effective to manage cases involving loss of hoof wall such as whiteline disease or injury. If you unload it, it will heal.”
Dr. Christine Hinterhofer spoke about the Biomechanics of the Equine Hoof Capsule, Using Finite Element Analysis. Dr. Hinterhofer’s work involved the creation of a computerized three-dimensional model hoof, which could then be loaded and analyzed. The model specified not only shape, but also stiffness and resiliency of the wall, sole, frog, digital cushion and coffin bone, as well as shoes and nails. It very closely approximates an average hoof in dimensions and properties, even down to having the wall at the quarters slightly thinner than the wall at the toe. When loaded, the model showed most stress at the quarters, particularly at the last nail.
“Breakover placed directly beneath the apex of PIII significantly reduces the forces of the deep flexor that is transferred to many sensitive areas via the weight of the horse. To better feel the mechanics of the foot, I visualize a simple but complex machine with cams, levers, pulleys and cables applying basic principles of physics.”
Figure 1. Hypothesized comparison of toe and heel angles, and base of support measurement differences in a “normal” hoof (at left) and a hoof with a long toe/low heel conformation (at right) which may increase the risk of suspensory apparatus failure. It is anticipated that a and a’ will be greater than b and b’, (D-C) will be greater than (B-A), and (a-a’) will be less than (b-b’) in injured horses compared with controls. Modified from Stashak TS, ed, Adams’ Lameness in Horses, 4th edition, Lea & Febiger, Philadelphia, 1987, pg 92.
Figure 2. Hypothesized effect of lateral displacement of the ground surface (at right) on lines of stress (load) which may cause eccentric lateral loading of the fetlock region and increased risk of lateral condylar fracture. Modified from Stashak TS, ed, Adams’ Lameness in Horses, 4th edition, Lea & Febiger, Philadelphis, 1987, pp 75 & 80.
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