The white line of the foot marks the division of the sensitive
and insensitive laminae, and laminitis occurs when these laminae become
inflamed. The normal blood flow to these tissues is disturbed, especially
in the toe area; this causes an interruption in the supply of oxygen
and nutrients to the laminae, without which the cells die. Inflammation
results, along with pain and swelling. Once this has occurred, separation
of the sensitive and insensitive laminae follows and is permanent. A
veterinarian or farrier can identify this situation by paring the sole
at the toe and seeing the telltale elongation of the white line.
This acute phase of laminitis is extremely painful for the horse and
may be attributed to many sources. Carbohydrate overload, systemic infection,
retained placenta and extreme weight bearing on one limb are just a
few causes. In the Spring, excessive consumption of lush green grass
is a leading instigator of laminitis. Horses that are overweight, especially
those that have developed a crest in their neck (indicating an excessive
amount of fatty tissue), are particularly prone to laminitis. Ponies,
too, show a high incidence, perhaps because of their metabolism.
Signs of acute laminitis are profound and are mostly linked to the animal's
response to the pain. Usually only the forefeet are affected, and the
horse takes on a characteristic stance with the hind legs well under
the body and the front extended forward. This position allows the animal
to take pressure off the front feet. The horse is very reluctant to
move, and when he does he has a stiff-legged gait, setting the heels
down first. If all four feet are involved, the animal will spend a great
deal of time lying down. Examination of the foot itself will reveal
an elevated temperature in the hoof at the wall, sole and coronary band.
A pounding pulse is present in the digital arteries, most readily felt
at the fetlock joint.
Founder occurs after the horse has passed through acute laminitis; it
may happen in the initial episode or during a later attack. The identifying
factor of founder is rotation of the coffin bone within the hoof capsule.
Often accompanying it is a dropped sole. Because the laminae are damaged,
the internal structures lose their support, and the pull of the deep
digital flexor tendon causes rotation. If the rotation becomes advanced,
the coffin bone can eventually penetrate the sole of the foot. The degree
of rotation can only be determined by radiographs. Hoof growth is altered
also at this point. The development of new wall is impaired, especially
in the toe region. Rings on the hoof wall illustrate the changed growth
pattern and are very prominent in chronic founder, often diverging from
toe to heel.
Treatment of acute laminitis consists mainly of eliminating the cause
and alleviating the pain. In the case where over consumption of grass
is the culprit, the animal needs to be moved to a drylot and kept on
a diet of hay and water. Historically, treatment included a regimen
designed to decrease the temperature of the foot and diuretics to flush
the horse's system of toxins; however, this is only successful when
caught in the very early stages. Walking is important for blood flow
within the foot, so the horse should not be confined to a stall. Too
much exercise, though, is risky, as it may promote more rotation of
the coffin bone. Keep the animal on soft footing to reduce concussion
on the sole and provide sufficient bedding so that he can lie down with
comfort. The veterinarian may prescribe drug therapy to alleviate the
intense pain in the early stages.
The farrier plays a crucial role in maintaining the horse with laminitis
and especially founder. Proper trimming and therapeutic will often restore
all but the most severe cases to a higher comfort level, while milder
ones may be able to work again. The most effective shoeing regimen involves
a bar shoe, straight, egg or heart, that transfers pressure from the
injured toe area to the heels. Many horses, after application of the
appropriate shoe, will walk off displaying little discomfort. These
shoes require careful maintenance, though; they must be cleaned daily
and checked for tightness against the foot, and the horse cannot be
turned into muddy paddocks. The farrier should visit the horse every
four to eight weeks to trim the hoof or reset the shoe, since it is
essential that the heels and toes of the affected feet be kept balanced
and in the proper proportions. For the owner, management consists mainly
of carefully monitoring the animal's diet and work load. It is also
the owner's responsibility to involve both the veterinarian and farrier
in the horse's rehabilitation schedule. These professionals are necessary
for recovery. Applying and resetting shoes may require the veterinarian's
presence and the use of a tranquilizer, as the pounding of nails in
the feet may prove painful. Periodic radiographs of the coffin bone
are also helpful in tracking the progression of the condition and making
shoeing decisions.
With the help of a professional farrier and veterinarian, and conscientious
care from the owner, the horse with laminitis or founder has a promising
future. He may not return to the previous level of work, but will certainly
have a more comfortable life. Quick identification of laminitis and
immediate treatment will help limit the effects. Proper management will
slow or prevent its progression. But the best bet is to take all steps
possible to diminish the chance of laminitis occurring.
