The Z bar shoe has gained
popularity with clinicians, both
veterinarians and farriers, when
faced with damage or infection to a
heel quarter / heel or heel on one
side of the hoof capsule (Figure 1A
& 1B). Among the injuries
encountered where it is commonly
used are heel bruising (corns), hoof
wall separations, quarter / heel
cracks, fracture of the bar and hoof
wall avulsions. The Z bar shoe has
become a popular forging exercise
but does it really possess the
purported benefits when used in
farriery practice? Farriery methods
used today are often based on
theoretical assumptions and hearsay
derived from empiric experience
rather than sound farriery
principles and proof of efficacy.
Central to our current knowledge
of farriery is the interaction of the
structures of the foot (especially
when damaged), the manner in
which the foot loads and the
surface on which the foot interacts.
So, if we consider the therapeutic
principles when confronted with
structural damage to a section of
the horse’s foot, there may be more
appropriate farriery options than
the Z bar shoe.
Fig. 1A shows a well forged Z bar shoe with an adequate frog plate. Fig. 1B shows the same shoe attached to a foot. Note the frog plate covering the frog.
(Courtesy of Jacques Kruger - South Africa).
It is important to realize and
understand the functionality of a
bar shoe. They provide stability to
the hoof capsule by the nature of
the bar joining the two branches of
the shoe together; placing a bar
between the heels of a shoe adds
several inches of ground contact
surface area to the foot; they
provide local protection and
recruitment of additional weight
bearing structures of the foot. The
continuity of the bar shoe around the
perimeter of the hoof capsule
allows a section of the hoof capsule
to be unloaded as there will be a
weight bearing surface in front of
and behind the affected area.
Furthermore, bar shoes decrease
the independent vertical movement
of the heels thereby reducing
movement and stabilizing the
structures in the palmar / plantar
section of the foot.
It may be helpful to consider
therapeutic principles when trying
to decide on the best farriery
approach for a foot with a
compromised heel / quarter or heel.
The therapeutic principles of
farriery used to promote healing of
any injured / diseased tissue or a
hoof wall defect are:
- Unload or decrease the force on
the damaged section of the foot
- Redistribute the load to a better
section of the foot
Fig.2. shows a Z bar show without a
frog plate which prevents redistributing
the weight of the horse to another
section of the foot.
Fig. 3A and 3B. Note the fulcrum effect
(red arrows) of the Z bar shoe and the
leverage on the hoof wall palmar /
plantar to the end of the shoe.
Perhaps the Z bar shoe should be
considered a partial bar shoe. The
bar of the Z bar is shaped with 2
90° bends such that one leg of the Z
is attached to the quarter of one
branch of the shoe and the other leg
is attached to the heel of the
opposite branch. This configuration
affords no protection to the section
of hoof wall not covered by the
shoe and leaves it vulnerable to
trauma from the surface below. The
Z bar shoe has limited ability to
unload or decrease the forces on the
exposed section of the hoof wall.
The Z bar shoe offers a floatation
effect when the horse stands or
walks on a hard-flat surface as the
affected area is off the surface.
However, if the horse stands or is
moved on a deformable surface
such as sand, synthetic arena
footing, grass paddock, etc.; the
weight of the horse will force the
shoe to sink in the footing and the
unprotected quarter / heel will be
directly engaged with the surface.
The same thing happens when the
horse is in the stall standing on
sawdust, shavings or other type of
bedding but to a lesser degree.
Furthermore, if we consider the
point in the quarter of the foot
where the Z bar turns medially
toward the frog; this forms a
fulcrum placing leverage on the
quarter / heel palmar or plantar to
this point (Figure 3). Therefore,
when the horse is weight bearing,
this leverage will create an
additional force on this area in a
The Z bar shoe would appear to be
able to redistribute a limited
amount of weight bearing to other
parts of the foot. However, in order
to transfer load, the Z bar would
have to have an adequate frog plate
that would cover the frog.
Furthermore, the frog and related
structures would have to be of
sufficient mass and healthy in order
to accept some of the weight
bearing function and make the
palmar / plantar section of the foot
‘load sharing’. The Z bar shoe is
hard to make properly, so many
cases seen in practice are just a Z
formation without the necessary
frog plate which then has no ability
to redistribute load and would
actually render the foot unstable
(Figure 2). Secondly, the ability to
redistribute weight is further
limited, due to the leverage and the
force exerted on the exposed hoof
wall as some of the load will be
placed here rather than over the
entire foot if a full bar shoe was
One last point that needs to be
considered is how the forelimb
(limb) conformation affects the
landing pattern of the horse. If a
horse lands slightly lateral heel first
and has a lateral heel injury;
removing a section of the shoe that
exposes the compromised heel will
alter the landing pattern and
increase the force during the
landing phase of the stride. A horse
with a rotational deformity or an
offset foot will land asymmetrically
and load the foot disproportionally
with excessive load being placed on
the medial side of the foot (sheared
heels). As many injuries and hoof
wall defects (quarter cracks) occur
medially; this will add excessive
force to the unprotected hoof wall
which is not conducive to healing
Alternative Farriery Solutions
There are many farriery methods to
implement the therapeutic
principles of protecting and
unloading a compromised section
of the foot and then redistributing
the load to a better section of the
foot. Any discussion of therapeutic
farriery and its ultimate success has
to start with and rely on a good
1,2,3 Briefly, a line is drawn
across the widest part of the foot, the frog is trimmed to remove exfoliating horn and the heels of the hoof capsule are trimmed to the base of the frog or to a point where the hoof wall at the heels and the frog are on the same horizontal plane. The toe length is reduced accordingly such
that there are approximate proportions of surface
area on either side of the line drawn across the
middle of the foot (Figure 4). Once a shoe is
chosen, the hoof wall on the affected side is again
trimmed from the toe quarter to the heel in a
tapered fashion to create a ‘pie shaped’ space
between the shoe and the hoof.
||Fig. 4. Basic trim –
red lines show the
widest part of the
foot and the
proportions on either
side of the widest
part of the foot. Blue
line shows the base
of the frog. Star is
of the center of
Fig. 5. Kerckhaert SX-8
straight bar shoe.
||Fig. 6. Heart bar shoe with a
healthy frog (Courtesy of Jeff
Ridley CJF, TE)
Fig. 7A and 7B. Kerckhaert SX-8 straight bar shoe with impression material.
Note the space created between the hoof surface and the shoe.
Fig. 8A and 8B. Kerckhaert SX-8 straight bar shoe with spider plate.
Note impression material removed under medial quarter / heel.
Open shoe with spider plate and impression material.
Note stiffness of spider plate will create a bar shoe effect.
Fig. 9. Complete avulsion of medial hoof
wall from toe quarter to heel.
There are many shoe or shoe combinations that can
be used. The shoe choice should be based on the
severity and extent of the damage or defect in the
affected section of hoof wall. All the shoes
mentioned will protect the affected area. If it is a
simple defect such as a quarter crack, a simple bar
shoe is generally sufficient. The continuity of the bar
shoe stabilizes the hoof capsule and allows the
section of the hoof wall with the defect to be
unloaded (Figure 5). Added stability can be added
by using a heart bar shoe which has the ability to
transfer some of the load to the frog and palmar
foot. In order for the heart bar shoe to be effective,
it is necessary to have a healthy frog of sufficient
mass (Figure 6). Another option to redistribute the
weight is to use a bar shoe with some form of pad.
Before applying the shoe and pad, impression
material will be added to the solar surface of the
foot except under the affected section of the foot so
that area stays unloaded (Figure 7). An excellent
combination to protect / unload the compromised
hoof wall and redistribute the load on the foot is to
use a bar shoe with a spider plate and impression
material. Again, the impression material is removed
from beneath the affected hoof wall (Figure 8).
A Clinical Case Using Farriery Principles
A 14-year-old upper level event horse suffered a severe avulsion of the right
fore medial hoof wall from the toe quarter to the heel (Figure 9). Immediately
after the injury, he was placed in a foot cast for 5 days and received antibiotics.
When presented out of the cast, he was toe-touching lame with a marked
digital pulse. Pressure on the avulsed area of the foot showed marked pain. To
initiate the principles discussed above, the horse was placed in a wooden shoe
which allowed the avulsed side of the foot to be unloaded and the weight to
be redistributed across the foot due to the flat solid surface of the block (Figure
10). The horse immediately became sound. As there was no infection present,
the detached section of hoof wall was left in place to act as a 'Band-Aid'. There
was solid hoof wall growth at the coronet a month later and the horse was
changed to a bar shoe / pad / impression material combination (Figure 11). At
the second reset (8 weeks), the hoof wall can be seen growing down solid and
evenly (Figure 12). Small portions of the detached wall have been removed
periodically with solid cornified horn underneath. The horse is turned out and
the hoof wall has continued to grow down uneventfully.
Fig. 10A and 10B. Wooden shoe at an initial farriery.
Note wall unloaded and screws inserted in toe.
Fig. 11A and 11B. Kerckhaert SX-8 straight bar shoe with leather pad
and impression material at 4 weeks
Fig. 12A and 12B. Reset at 8 weeks (12A) and 12 weeks (12B).
Note hoof wall growth at coronet.
Farriery is both an art and a science. I like to use a thought process based on principles when devising a therapeutic plan.
In most cases the principles for damaged tissue will be to protect, take the force of it and redistribute some of the weight
bearing function to another part of the foot. I try not to think about what I did on the last case but what I’m going to do
for this case. There are always a variety of ways to apply principles.
- O’Grady, SE. (2009) Guidelines for Trimming the Equine Foot: A Review. Proceedings, Am Assoc Equine Pract 55. 218-225.
- Castelijns, HH. (2012) The Basics of Farriery as a Prelude to Therapeutic Farriery Vet Clin N Am Equine 2. 316-320.
- O’Grady, S.E. Farriery for Common Hoof Problems. (2011) In: Baxter GM, ed. Adams and Stashak’s Lameness in Horses 6th ed.
Ames, IA: Wiley-Blackwell, 1199-1210.
- O'Grady SE., Castelijns, HH. (2011) Sheared heels and the correlation to spontaneous quarter cracks Equine vet edu 23. 262-269.