BACK TO BASICS: LAMENESS AND PODIATRY


fissures, punctures, consistency, discoloration (bruis- ing), and the degree of concavity. The shape of the sole should be concave. If it is not, then the sole will be either flat or convex. A flat sole may signify either poor hoof conformation (a weak hoof) or coffin bone displacement. A convex sole, however, indi- cates a displaced coffin bone. The consistency (rel- ative degree of stiffness) is usually determined using digital pressure as well as hoof testers. At this point, it is necessary to evaluate the texture of the sole. By grasping the quarters with your fingers, the thumbs can be used to gently press on the sole. If the sole moves under this pressure, it is thin and the examiner knows that there is little space be- tween the coffin bone and the outside environment. On the other hand, if the sole does not move, the examiner knows there is at least some thickness and depth to the sole. The true sole depth can be deter- mined later via radiography. The white line is examined to determine its width


and character.1 The white line is usually wider at the toe and gradually tapers to a thinner structure as it approaches the heels. It is best visualized following either light paring with the hoof knife or light rasping of the superficial portion of the foot. It is used to demarcate the insensitive hoof from the sensitive hoof for the purpose of driving horseshoe nails. Everything outside the white line is insensi- tive, everything inside is considered sensitive. Wid- ening of this area represents stress and separation of the laminar hoof wall from coronary hoof wall. The deeper the separation goes, the more severe the injury. This separation can be seen anywhere on the solar surface and indicates a bending force on the wall that is pulling the wall away from the coffin bone. Most frequently, this separation is seen at the toe and is referred to as “seedy toe,” because it looks like small seeds could fit between the spaces created by the separation. From the rear (palmar/plantar) of the hoof, exam-


tarsus) and allow the foot to drop naturally.1 Posi- tion your line of vision so as to appreciate foot balance and levelness of the walls. Imagine a line drawn through the axial center of the limb, which transects the ground surface of the foot, and then determine the relative proportion of medial and lat-


ine the bulbs of the heels to determine their relative position to one another.1 The strength of this tis- sue is assessed manually by attempting to distract the two bulbs from one another in a vertical direc- tion. Digitally explore the heel bulbs for the pres- ence of swelling, heat, pain, or separation at the coronet. The central sulcus of the frog needs to be examined and probed to determine its depth. Nor- mally, this should be a shallow depression of no more than a centimeter. If the sulcus goes deeper, there may be either very serious thrush or loss of structural support in heel bulbs, in which case the heel bulbs can be distracted in opposite vertical directions. Lightly support the limb at the metacarpus (meta-


eral foot to this imaginary line. For example, a given foot may demonstrate a unilateral medial heel contraction in combination with a flared lateral quarter and toe (diagonal imbalance). Repeat the palpation of the cartilages of the distal phalanx and the coronet.1 Bringing the limb for- ward and flexing the toe facilitate palpation in the region of the extensor process of the distal phalanx region and the associated distal interphalangeal joint. The thumbs or index fingers can then be pressed over this area to feel for joint distension, heat, or pain. The foot also should be rotated (twisted) medially and laterally around the vertical axis of the pastern. A normal range of motion allows for 10–15 degrees of rotation each way. Injury to the joint capsule, collateral ligaments, or chronic navicular pain tends to reduce this motion. Likewise, distal limb flexion should reveal 30–45 degrees of excursion. Again, injury to the joint capsule, collateral ligaments, or chronic navicular pain tends to reduce this motion. If the horse is shod, the exam should include the following additions.3 First, determine the security of the shoe to the foot by gently rapping the shoe at one-inch intervals with a shoeing hammer. Make note of the shoe type as well as the presence or absence of additions, such as toe grabs, block heels, trailers, and so forth. Carefully determine if abnor- mal shoe wear exists. Position the hoof testers to include the hoof wall at the exit point of each nail. Carefully record your findings, as it is easy to forget subtle discoveries that may ultimately determine how the horse should be treated or shod. Keep in mind that hoof testers are essential but certainly not foolproof. The response the examiner gets on hoof testers is dependent on many factors, such as the hardness of the wall, depth of the hoof, thickness of the hoof, and the stoicism of the horse.


4. Objective Assessment


As part of any evaluation of the hoof, an objective assessment of hoof balance is important. Measure- ments are made of each forefoot.6 The horse’s weight is determined with a weight tape or scale. Measurements are made of the hoof length with a tape measure (these can also be done using com- puter programs): medial and lateral heel lengths, vertical distance from the heel coronary band, and sagittal toe length. In addition, the frog’s length and width are measured at their longest and widest points. The hoof angle is measured using a hoof gauge, and hoof circumference is measured immedi- ately below the coronary band. These measure- ments are used to compare right to left but they can also be used to calculate the frog ratio (frog width divided by length), body size to hoof area (horse’s weight [pounds]  12.56/square of the hoof wall circumference [C] [inches]), and the heel measure- ments, with the vertical distance of the heel to the ground used to calculate the angle of the heels. These measurements can be used to identify mea- surable hoof imbalance.6 A lateral radiograph can


AAEP PROCEEDINGS  Vol. 64  2018 343


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