stride between the time the horse's heels lift off the ground and the
time the toe lifts off the ground.
There are several approaches to preventing interference in the fetlock
area, the most common area for interference. Horses that tend to interfere
will breakover on the outside of their front feet rather than the middle
of the toe. The point of breakover can be detected by examining the wear
on the hoof or how the horse is wearing the shoe at the toe.
The hoof-flight pattern of a horse that toes out may be widened to some
degree by your farrier, who will lower the outside hoof wall and rasp
off any flares, especially those on the inside of the hoof wall. Shims
or wedges may be placed between the shoe and the hoof in extreme cases
to increase the distance between the limbs during movement. Keep in mind
that such changes to the feet only manipulate the timing and direction
of the gait rather than changing the gait itself.
The breakover can be shifted toward the center of the toe by using a
square-toed shoe. Lateral (outside) support of the toe at the moment of
breakover can also be achieved by using a lateral extension-toed shoe.
Shoes used on horses that interfere should be smoothed so there is no
sharp edge to cause damage if the horse strikes the opposite limb.
There are several other types of interference. Knee-hitting, also called
knee-knocking is rare in performance horses. It occurs when the inside
of the front foot strikes the knee on the opposite limb. The cause of
knee-hitting is basically the same as described for fetlock interference
except that, in addition, the foot twists at the moment of breakover.
Besides the prevention or correction that is used for fetlock interference,
jar calks welded on the heels will hold the foot on the ground at the
moment of breakover and reduce the amount of twisting.
Elbow-hitting is interference between the heel of the shoe and the elbow
of the same leg. Again, this form of interference is rare. It is mostly
seen in horses that work at speed or gaited horses. Continual elbow-hitting
can cause a shoe boil to develop. Reducing the weight of the shoe and
increasing the hoof angle may correct horses that hit their elbows.
Many horses hit their elbows because of excessively long pasterns. Bandaging
the fetlock with a light bandage during work will eliminate this type
The best approach for correcting a gait fault is to examine the animal's
conformation and foot-flight pattern. The forelimb conformation should
be assessed with the horse standing squarely on a hard surface. The position
of the horse's feet, whether the foot turns in or out, the presence of
a wide or narrow chest and the direction the knee faces should be noted.
The horse should be observed walking and trotting directly away from and
toward the examiner so he or she can observe the flight pattern and the
manner in which the foot strikes the ground. The information gained from
this brief examination will allow the examiner, usually your farrier,
to formulate a plan to correct the particular gait abnormality.
Most cases of forelimb interference can be prevented or improved by corrective
shoeing. For occasional interference or interference encountered during
certain phases of training, protective boots are often more helpful than
changing shoes or hoof angles. Changing riders or riding techniques can
improve many limb interference problems. Some horses cannot be completely
corrected while others will improve only temporarily.
Fatigued horses commonly interfere. A lighter shoe such as aluminum may
be of benefit.
Look before you leap. All types of interference can be detrimental to
peak performance in the horse. It is important to look for this potential
problem during a prepurchase examination.
The examiner should look for scars or fibrous thickenings along the inside
of the horse's leg. Strict attention should be paid to the animal's conformation
and observing limb movement on a hard surface. Often it can be determined
whether a horse has interfered in the past or if it is inclined to interfere
when placed in strenuous work.
Dr. Doug Butler, a well-known author and farrier, says stumbling
is also a form of interference of the hoof with the ground.
"Stumbling is often blamed on laziness or on a hoof that is long
and in need of trimming," observes Dr. Steve O'Grady. "Although
the long toe can be responsible in some cases, it may be the exception
rather than the rule."
He explains that shortening the toe of the foot and increasing
breakover should correct the problem if hoof length is the cause.
"A more likely cause of stumbling is heel pain. This will force
the horse to land on its toe to avoid the discomfort in the heels
and promote stumbling," notes the veterinarian.
"A thorough lameness examination including diagnostic anesthesia
is used to confirm or rule out heel pain."
Another remote possibility for subtle stumbling is a neurological
disease such as EPM.