|Take home message
A successful quarter crack repair should be simple, strong,
safe to apply and durable. It must be emphasized that the
cause of the crack must be addressed in order to prevent
Quarter cracks are a common cause of foot lameness and/or
decreased athletic performance in race and sport horses. They
typically originate at the coronary band and continue
distally. They are full thickness, extending into the dermis
of the hoof, which leads to instability, inflammation and/or
infection. Quarter cracks are painful due to infection and/or
the result of instability caused by movement of the hoof wall
posterior to the crack. The vertical movement of the heel bulb
on the affected side further complicates this instability.
Causes of quarter cracks may include trauma to the coronary
band, preexisting damage to the corium from infection,
abnormal hoof conformation; especially the long toe underrun
heel, focal foot imbalances, short shoes or an abnormal
landing pattern when the foot strikes the ground.
Often the problem facing equine practitioners is that many of
the horses that develop quarter cracks must continue to
perform. For this to occur, it is essential for the repair to
provide strength and stability to the hoof wall defect,
allowing the horse to perform while at the same time promoting
healing so that the crack will grow out. Various techniques
for repairing hoof cracks have been described. They include
corrective shoeing, stabilizing the crack by placing implants
across the defect and covering the crack with an acrylic
material 1. This report describes a simple,
consistent method of repairing a quarter crack that, when
combined with appropriate shoeing, gives superior stability.
Correct the Cause
For a successful repair, it is necessary to try to determine
the underlying cause of the quarter crack and to correct it
where possible. Horses with long toe underrun heel foot
conformation appear to be prone to quarter cracks. This type
of heel may be weak due to insufficient hoof wall growth and
there may be insufficient ground surface to adequately support
the palmar/plantar part of the foot. In addition, there may be
increased pressure in the quarter and heel during the stance
phase as a result of delayed breakover caused by the long toe.
On the other hand, upright hoof conformation with high heels
promotes heel first landing, which increases pressure through
the heels and quarters often leading to a hoof wall defect.
Short shoes leave the
heels unsupported and put the weight-bearing surface in front
of the vertical axis of the limb. In such instances, a
vertical line drawn from the origin of the quarter crack will
invariably coincide with the end of the shoe (Figure 1). The
use of an aluminum plate with a toe grab as used in racehorses
raises the toe, creating a broken-back hoof pastern axis. This
would also appear increase the pressure in the posterior part
of the foot.
Of utmost importance is the landing phase of the stride. Many
horses will contact the ground asymmetrically, landing first
on one side of the hoof and then impacting with the opposite
side. This type of strike pattern may be related to
conformation but can also be caused by inappropriate trimming.
This type of stride may place excess forces on one side of the
hoof wall, and may cause enough force to proximally displace
the heel bulb. When coupled with abnormal foot conformation,
this landing pattern may lead to a shearing force in the
lamina. The landing pattern and the conformation of the foot
may also perpetuate quarter cracks caused by trauma to the
coronary band or a previous abscess.
Methods and Materials
When infection is present, it is characterized by marked
lameness; pain on palpation and a swollen discolored coronary
band above the defect. Occasionally, exudate can be expressed
when digital pressure is applied to the coronet. If infection
is present, the crack should be opened and bandaged with 2%
iodine, or a similar disinfectant agent, for at least 48 hours
before the repair.
Before beginning the quarter crack repair, the shoes should be
removed and the feet trimmed appropriately. In horses with the
long toe underrun heel conformation, attempts to move the
breakover back is helpful. The hoof wall is always lowered on
the affected side. Lowering the hoof wall of the quarter and
heel beneath the quarter crack will decrease the amount of
impact when the foot strikes the ground.
When starting the repair, the hoof wall should be thoroughly
cleaned and dried. The
quarter crack is opened its entire length using a Dremel
a tool a with a tungsten carbide bit, being careful
(especially near the coronary band) not to create any
unnecessary hemorrhage. All necrotic and loose horn should be
debrided in the area of the crack. The hoof surface on either
side of the defect should be sanded using the Dremel tool with
a coarse grit drum sander. Two sets of paired 3/64-inch holes
one quarter inch apart are then drilled on either side of the
crack beginning at least ½ inch from the margin of the crack
and ending within the depths of the opened area. Stainless
steel (21-gauge) wire is bent in a "hair pin" shape 2.5 inches
long and a small steel tab is placed on each wire unit (Figure
2). One wire unit is passed through the holes from palmar to
dorsal direction and another wire unit is passed through the
opposing holes in a dorsal to palmar direction into the depth
of the crack. The ends of all the wires are pulled tight and
bent outwards. The tab placed on the wire unit will now lie
against the outer hoof wall. This prevents the wires from
cutting into the hoof wall. Additional sets of these wire
units can be used according to the length of the defect or
until the desired stabilization is achieved.
If the crack leads into the dermis, it cannot be completely
eliminated. In all such cases, a drain is placed. .
To place a drain, a small amount of medicated putty b
is rolled into a tubular shape and placed over the length of
the remaining defect within the debrided crack. One-eighth
inch hollow rubber flexible tubing is pressed into the putty
and will exit at the coronary band to form the drain (Figure
3). The ends of all the
opposing wires are now joined together and twisted until
resistance is felt. The excess wire in front of the twist is
cut off within the defect (Figure 4). There should be no
movement in the hoof wall posterior to the crack when digital
pressure is applied.
Next, elastic adhesive tape is placed around the coronary band
to prevent irritation from contact with the composite. Three
sections of a strong structural fabric that resembles
fiberglass, called "spectra", c is cut 2x3 inches.
The previously sanded hoof is rinsed with free-flowing
denatured alcohol. The polymethylmethacrylate composite (PMMA)
d. is mixed thoroughly and a layer applied to the
prepared area of the foot, being sure to fill the quarter
crack 2. The spectra fabric is impregnated with the
PMMA composite and placed over the prepared area followed by a
layer of composite. This procedure is repeated until three
sections of fabric have been placed over the defect. Finally,
the hoof wall is wrapped in plastic wrap and an elastic
adhesive bandage is pulled tightly around hoof wall,
compressing the fabric. Upon completion of the cure cycle,
which takes two to three minutes, depending on the ambient
temperature, the rubber drain is removed and the repair is
sanded to remove excess composite.
Choice of Shoes
Any horse with a full thickness quarter crack that warrants
repair should be placed in a bar shoe if possible. Various
configurations of bar shoes are a straight-bar, egg-bar,
heart-bar or Z-bar shoe. All of these shoes effectively
increase the bearing surface of the foot, provide palmar/plantar
support, and decrease the independent vertical movement at the
bulbs of the heels. No nails are placed into the repaired area
of the foot.
Recently, this author has glued the shoes on most horses with
quarter cracks. Gluing the shoe offers several advantages.
First, it allows the foot to be trimmed and shod to a more
suitable foot conformation. Second, gluing on the shoe allows
for more expansion to be provided under the quarter and heel
thus increasing support. Finally, when shoes are glued on,
there is no concern with nail placement in the affected
Combining an implant and a composite in repairing a quarter
crack increases the strength and durability of the repair.
Types of implants described previously include fiberglass and
screws, screws and wires, various suture patterns and clamps
that apply tension across the crack 1,4,5. These
methods have been somewhat cumbersome; the screws present a
risk as they often impinge on the dermis and uniform tension
is rarely achieved across or within the crack.
The advantage of the method described in this report is that
the wires are placed from opposing sides of the defect and
joined together within the defect creating uniform tension
within the crack. The wires are also incorporated into the
composite as part of the repair. Another advantage of this
technique is that, since the implant is contained within the
hoof wall, there is very little metal on the surface of the
hoof wall to interfere with the adhesion of the composite.
Many failures in quarter crack repair appear to result form
the rigidity of the acrylic material used and its resultant
inability to maintain a consistent bond to the hoof wall long
enough to allow healing. The
polymethylmethacrylate used in recent years has excellent
adhesive characteristics with the horn wall, while having a
flexibility that approximates that of the hoof itself, thus
more closely approximating normal function 6. The
addition of spectra to the composite, instead of fiberglass,
increases the strength of the overall repair due to its high
tensile strength. Placement of a drain effectively decreases
the risk of infection under the repair.
The importance of determining the underlying cause, proper
trimming of the feet and applying the correct shoe cannot be
over emphasized when repairing a quarter crack. The palmar/plantar
support provided by the appropriate shoe is as important as
the repair itself. This technique described here for quarter
crack repair has produced consistent results, and horses are
able to return to almost immediate soundness. In addition,
horses treated in this manner have been able to return to
successful competition following the repair, and no infection,
reoccurrence or bond failures have been noted.
1. Moyer, W.: Repairing hoof cracks in the horse: A review
and a report of a new technique. Comp. Cont. Ed. 1983 ;
2. Moyer W, Sigafoos R. Preliminary experience and uses of
composite hoof wall repair, in Proceedings. 37th Annu Conv Am
Assoc Equine Practnr 1991; 681-686.
3. O'Grady S.E., Watson E., How to glue on therapeutic shoes.
Proc. 45th Annu. Conv. Am. Assoc. Equine Practnr. 1999;
4. Butler, J.: The repair of hoof cracks using fiberglass and
screws. Proc. 22nd Annu. Meet. Am. Assoc. Eq. Practnr 1976;
5. Blackford JT, Blackford LAW, Latimer FG: Adjustable tension
band stabilization of hoof cracks in horses. Proc. 37th Annu
Conv Am Assoc Equine Practnr 1991; 497-512.
6. Moyer W, Sigafoos R. Equine hoof wall repair. Trenton:
Veterinary Learning Systems, 1993, 6.
a. Dremel® Dremel Tool Co. Emerson Electric, 4915 21st.,
Racine, WI 53401
b. Keratex® putty - Advance Equine P.O. Box 54 Versailles, KY
c. Spectra® Equilox Int'l 110 NE 2nd Street, Pine Island, MN
d. Equilox® - Equilox Int'l 110 NE 2nd Street, Pine Island, MN