Page 537 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Distal Limb 503

To attempt to realign the distal phalanx with the performed to transfer weight‐bearing from affected
ground surface with the sole by trimming, the ground lamellae to the sole, bars, and frog to decrease stress in
VetBooks.ir decrease the thickness of the dorsal sole further. weight‐bearing to spare weight‐bearing by the wall has
the affected lamellae. However, the role of the sole in
surface of the foot to one plane would inevitably
been questioned (see therapeutic shoeing in Chapter 8).
Therefore, only that portion of the foot with greater
than 15 mm sole depth is trimmed, which is usually the Regardless of the theoretical considerations, some
palmar 50%–70% of the sole (Figure 4.74B). This horses appear to benefit greatly from sole support.
results in two separate planes for the dorsal and palmar Support of the ground surface of the foot is most read-
portions of the foot (Figure 4.74B). Depending on the ily accomplished with the use of synthetic polymers
shoeing technique to be employed, the dorsal plane of such as polymerized silicone (two‐part putties such as
the foot may be brought into line with the palmar plane the impression material [Equine Digit Support System
at the time of shoeing, usually by filling the gap with a (EDSS), Penrose, CO] or advanced cushion support
synthetic polymer. The plane for trimming can be identi- [NANRIC, Lawrenceburg, KY]) or polyurethane (“pour‐
fied on the radiograph by drawing a line parallel to and in pads”) in the space between the branches of the shoe.
15 mm distal to the solar margin of the distal phalanx However, support of the ground surface is also still
(Figure 4.72). approached by more traditional means such as pads
Some horses, particularly those with mild rotation and heart‐bar shoes.
and sufficient sole depth, may be managed with trim- Several shoe types have been used to address these
ming and maintaining them on a soft ground substrate goals including regular keg shoes, egg‐bar shoes, reverse
without shoeing. shoes, heart‐bar shoes, four‐point rail shoes, and wooden
Once the foot has been trimmed, the clinician must shoes/clogs. Each deserves consideration to examine
decide whether or not to shoe the horse, and if so, which how it accomplishes the goals and to discuss its advan-
type of shoe to use and how to attach it. The shoe may tages and limitations.
be attached to the foot with nails, directly with glue, The keg shoe must be modified to be effective in the
with glue and a cuff, or, in some instances, with cast treatment of active and stable chronic laminitis. Break‐
material (i.e. the wooden shoe). The type of shoe and the over in the dorsopalmar plane can be eased by forging
manner in which it is attached vary with duration and the toe of the shoe to square and roll it and setting the
severity of diseases and clinician experience and prefer- shoe back. Easing break‐over in the medial and lateral
ence. For less severely affected horses, most frequently, directions can be achieved to a limited extent by rounding/
shoes are nailed to the foot in the traditional manner. beveling the outside rims of the branches of the shoe.
However, when nailing the shoe in place is considered Heel elevation can be added as needed by using a shoe
too painful or there is insufficient hoof wall to which to with a built‐in wedge or using a wedge pad, frequently a
nail, a less traumatic technique using a combination of wedge rim pad. The wedge rim pad allows incorpora-
adhesives, casting tape, and screws may be used. When tion of as much of the ground surface of the foot as
selecting a shoe, it is important to remember that there needed for weight‐bearing using a synthetic polymer in
are several underlying principles and numerous ways of the concavity of the foot between the branches of the
achieving them. The underlying principles or goals of shoe (and rim pads).
shoeing include: The egg‐bar shoe (Figure 4.75) is probably the most
common shoe used because it is readily available and
1. Moving the center of pressure many farriers and veterinarians are familiar with its use
2. Changing the area of distribution of force in other circumstances. It can be modified in all the same
3. Decreasing the shock of impact ways as the keg shoe, and it has the added benefit of the
4. Enhancing ease of movement
5. Protecting parts of the foot
Enhancing ease of movement involves decreasing the
moment arm about the DIP joint and smoothing out
break‐over. This is most beneficial in the dorsopalmar
plane, in which the objective is accomplished by rolling
the toe, setting the shoe back, squaring the toe, or using
an open toe shoe. However, to a lesser extent, break‐
over in a medial or lateral direction can be eased by the
use of rails, rounding the medial and lateral branches of
the shoe, or using a Steward clog (wooden shoe) with
beveled sides.
For horses with rotation, the center of pressure may
be moved in a palmar direction in relation to the center
of the ground surface of the foot and toward the center
of rotation of the DIP joint by using extensions, by
recruiting more ground surface to bear weight on the
palmar ground surface, or by elevating the heels. In
doing so, weight‐bearing can be moved away from the
most affected laminae.
Increasing the area of distribution of weight across
part or all of ground surface of the foot is theoretically Figure 4.75. Egg‐bar shoe.