Shoeing in the Frontal and Horizontal Planes

When evaluating horseshoeing, many people don't look at the hoof correctly, according to Hans Castelijns, DVM and farrier based in Italy. "There are the sagittal, frontal, and horizontal planes (illustration included in this story)," he said in his presentation "Shoeing in the Frontal and Horizontal Planes" at the 16th annual Bluegrass Laminitis Symposium in Louisville, Ky. "You can have conformational problems in all planes.

Frontal, horizontal, and sagittal planes

One of his first bits of advice was to be careful about drawing conclusions regarding how a domestic horse's hooves should be shaped based on information from wild horses. "Feral horses are not wild, just horses that escaped from humans that were once bred for a purpose, and conformation has much to do with breeds," he explained. "And you can't run a 1:48 mile with a feral horse. They are adapted for survival in the wild, not athletic pursuits."

If you have a young horse with hoof/leg conformation problems, Castelijns said you need to act quickly. "The way they're raised has tremendous influence on their feet," he said. "Adapt shoeing and trimming as needed when they're young. The possibility of correcting conformation faults is dependent on having active growth and is attempted by influencing growth plate development; therefore, this should be attempted at an early age (first year of life).

"Also, most developmental problems are due to overfeeding; the horse that will grow very tall often has more of a chance to develop mismatched feet," he commented.

Adult Horses

Moving on to handling conformation problems with adult horses, Castelijns stated: "This paper proposes to address the relationship between hoof shape and leg conformation in the frontal plane and horizontal plane, and the consequences of trimming and shoeing in these planes."

He first discussed angular and rotational deviations (ADs and RDs), noting that, "The first can best be evaluated by viewing the horse from the front or the back (in the frontal plane), the second by looking down the limb when standing close to the horse (in the horizontal plane). ADs and RDs are often associated and can occur at multiple sites (joints) in the same limb and should therefore be carefully noted. Both types of deviations cause joints to work at abnormal angles to the sagittal plane of the horse, which is also the plane in which the horse moves when not turning, equine limb joints having evolved to function mainly as hinges at 90° to the sagittal plane.

"ADs cause the affected joints to be loaded unevenly in the lateromedial (side to side) sense with both increased loading on the articular cartilages on the concave side (the one on the inside of the unusual bend in the joint) and increased tension (pulling) on the collateral ligaments on the convex side (the one to the outside of the unusual joint bend)," he continued. "RDs affect the joints in a diagonal plane, again with uneven stress on articular cartilages and collateral ligaments.

"Another consequence of these conformation defects is that they tend to alter the flight path of the limb during suspension," he noted. He explained that inward rotations usually result in winging out (away from the center of the body) of the affected limb(s) during flight, with landing often on the medial (inside) heel and breakover on the outside toe of the foot. The reverse is true for outward deviations.

Regarding navicular syndrome, Castelijns noted that affected horses are usually older ones in disciplines that involve a lot of turning or work on uneven terrain. "We're taught that navicular problems are due to long toe-low heel conformation," he said. "But I think it might be more due to repetitive asymmetrical loading of the foot."

Conformation Problems and Hoof Shape

The result of an angular deviation, Castelijns stated, is usually atrophy of the side of the hoof opposite the deviation. For example, an outward deviation of the lower leg (such as below a carpus valgus, or knocked knees) would result in a relatively atrophied medial (inside) aspect of the hoof. This appears to be a functional adaptation to keep the joint spaces even, he added. This way, "they have more evenly spread lateromedial pressure across their surfaces and with more even tension on the collateral ligaments during weight bearing."

With rotational deviations, he explained, "the hoof capsule adapts by atrophying diagonally across the hoof, along a line that is parallel to the sagittal plane of the horse; e.g., an inward rotation causes medial heel and outside toe atrophy. When those relatively atrophied hoof parts are connected by a line, this line is parallel to the sagittal plane of the horse, but not to the sagittal plane of the hoof." This seems to be another functional adaptation, he said, resulting in decreased torque on the poorly conformed joint at breakover and landing of the heel.

Trimming/Shoeing Conformation Defects

Armed with a better understanding of these deviations and how the horse adapts to them, the audience relished the discussion of what to do about them. Castelijns stated that correction of these joints with shoeing is not possible in the adult horse, but noted that minimizing abnormal stress in the affected joints (and thus improving the likelihood of soundness) is possible.

"Trim and shoe the horse with conformational defects in the frontal and horizontal planes so that the joint spaces remain even," he recommended. "To obtain this it is usually appropriate to recognize and respect the hoof shape, even though in severe deviations this shape looks out of the ordinary." He added that evaluating the white line would give one a better idea of the true hoof shape than the outside wall, which has a tendency to flare unevenly with uneven stresses.

"Since relatively atrophied hoof parts expand less and are usually thinner, these should not be burdened with clips or nails that are better concentrated at the overdeveloped parts of the hoof capsule," he suggested. "And although it makes for a more symmetrical hoof plus shoe outline (looking better than fitting the shoe to the asymmetrical foot), setting a shoe wide and/or long especially under an atrophied heel may actually cause inward and upward pressure on the hoof wall at the affected heel. These heels, which are easily shunted upward and sheared (the biggest movement in the hoof is vertical movement between the bulbs), often are the sites of spontaneous hoof cracks due to ungual cartilage meeting the upwardly shunted coronary band from the inside, when bending outwards during weight bearing. A sheared heel is a frequent consequence, then a quarter crack.

"Asymmetrical shoeing can be important for the pathological shoer (one who shoes problem feet)," he explained. "You have to adapt the shoe to the foot rather than trying to make a weird foot look good."

"Horseshoes that bring lateromedial breakover closer to the hoof's center will diminish joint stress and should perhaps be used preventively in horses with conformation defects, and not only after arthrosis (joint disease) has set in," he suggested. He listed several shoes that sport at least a rounded outside ground surface edge (rather than those made with square-edged stock) as possibilities. Also, he noted that winging in or out decreases with these shoes, and that appropriate shoeing intervals should be observed with affected horses.

Lateral or medial extensions can be used for correction of foals, influencing gaits, and as therapy for certain pathologies that exist clearly on one side of the affected limb, Castelijns commented.

"When holding an asymmetrical hoof, it is good practice to put it down and take the time to analyze the conformation of the limb it is attached to," he summarized. "Beware of the urge to always obtain nice, symmetrical, 'normal' feet, which might be more pleasant to behold, but which might not respond to the biomechanical needs of a horse affected with angular or rotational deviations."

About the Author

Christy M. West

Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.

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