|Thorough examination of the horse affected
with navicular syndrome is important not only to determine
that the horse has the syndrome but also to try to determine
which type of disease process is at work. Treatment then
should be based on the type of injury.
The treatments of
navicular syndrome vary widely, which probably reflects the
treatment of multiple causes. By determining the most likely
cause of the syndrome, the most specific problem can be
treated. The treatment of navicular syndrome is as
controversial as any aspect of this disease. However, it has
been shown that correct shoeing should be basis of all
treatment. Any medicinal or surgical therapy should be as an
adjunct to shoeing.
The most successful approach to shoeing is that based on
individual case needs rather than a standard formula. The
following principles should be followed: (1) Correct any
pre-existing problems of the hoof, such as underrun heels,
contracted heels, sheared heels, mismatched hoof angles,
broken hoof/pastern axis. (2) Use all weight bearing
structures of the foot. (3) Allow for hoof expansion. (4)
Decrease the work of moving the foot. Shoeing is most
effective when corrections are made within the first 10 months
of lameness, up to 96% success. This is in contrast to when
shoeing changes are not made until after 1 year of lameness,
where only 56% of the cases have been successfully treated.
These principles can be accomplished using many different
methods and techniques. Shoeing is of utmost importance in
dealing with hoof pain causing the signs associated with
navicular syndrome or remodeling of the bone (osseous form).
It is necessary to insure proper hoof balance and support in
order to eliminate the pain and stop or decrease the stresses,
which are causing the problem.
Horses that respond to coffin joint anesthesia should be
treated for inflammation of that joint. This may include
systemic non- steroidal anti-inflammatory therapy but intra-articular
therapy or specific joint therapy should also be considered.
The use of hyaluronic acid and corticosteroids as anti-inflammatories
within the joint is well documented. I prefer to use a
combination of high molecular weight hyaluronic acid (10mg)
and triamcinolone (8mg) injected intra-articularly followed by
a second shot of hyaluronic acid in 2 weeks. In addition, the
use of intra-articular or intramuscular polysulfated
glycosaminoglycans (Adequan) has been useful in the control of
joint disease. Most frequently I use PSGAGs if I suspect
cartilage damage (500mg IM, weekly for 4 weeks). Cartilage
damage, at least on the flexor surface, can most easily be
assessed by contrast navicular bursagraphy.
Occasionally horses affected with coffin joint synovitis
also have a chronic broken forward hoof axis. Many of these
cases appear to be mild flexural deformities. Because of the
mal-articulation of the short pastern and coffin bones, the
joint remains inflamed despite therapy. In these cases,
inferior check desmotomy to allow correction of the broken
forward axis has been a very useful in treatment of these
types of cases.
Vascular forms of the disease can be treated with
vasoactive drugs. Isoxsuprine Hcl is the most common drug used
to increase the circulation to the podotrochlea. It is dosed
at 0.6-1.2mg/kg b.i.d. until sound, then decreased to s.i.d.
for 2 weeks then further decreased to every other day.
Other drugs have been studied. Metrenperone is a serotonin
antagonist and thereby increases circulation. It has been used
at a dose of 0.1mg/kg b.i.d. However, the drug has not been
shown to be as efficacious as isoxsuprine. A new drug that is
showing promise is pentoxifylline, which increases RBC
deformability and thus aids circulation. The drug is dosed at
4.5-7mg/kg t.i.d. Clinical trials in Canada have shown much
Some surgeries have been suggested to be useful in the
treatment of vascular forms of the disease. Palmar digital
neurectomy causes vasodilation and the effect lasts as long as
the neurectomy. Fasciotomy of the palmar digital nerve has
also been suggested but the effect does not last and may cause
more damage to the nerve.
In cases where desmitis of the navicular suspensory
ligament is suspected there are basic 2 treatment
alternatives. Treatment is designed to reduce strain on the
ligament. This can be achieved by either raising the heels of
the horse's foot or by cutting the collateral sesamiodean
ligaments (CSL). Collateral sesamoidean desmotomy is a surgery
that has become popular in Europe and has been effective on
selected cases of navicular syndrome. The surgical approach is
made just proximal to the collateral cartilages, just cranial
to the digital vein. A 2cm incision is made, the vein is
retracted palmarly, and the CSL can be located as it courses
proximally and dorsally over the short pastern bone. A
hemostat is used to dissect around the ligament and then
transection is performed. Closure is standard. The horses are
allowed to rest for 2 weeks for skin incision healing, then
they are returned to work.
Similarly, when the deep flexor tendon is involved, raising
the heels of the hoof will decrease strain on the tendon. But
in addition, desmotomy of the inferior check ligament has also
recently been shown to be effective in treatment of these
Podotrochlear bursa lavage has been suggested for the
treatment of true cases of navicular bursitis. Ingress and
Egress needles are placed in the bursa and isotonic fluid is
flushed through the bursa to remove any inflammatory debris.
When all other treatments have failed or have not had the
desired affect, palmar digital neurectomy remains a viable
treatment alternative. Numerous techniques are available but
all follow some basic rules. First, the neurectomy will not
improve the lameness any more than a palmar digital nerve
block. Therefore, it is highly recommended that the nerves be
anesthetized with the owner/rider present so that they can
decide whether the horse has sufficiently improved. Second,
neuromas are a common problem but can be avoided by atraumatic
surgical technique. Atraumatic surgery can really only be
learned by practice. Neuroma formation can be decreased by
allowing the surgical wounds to heal as well as possible
before returning to work. This usually requires 4 to 6 weeks
rest after the surgery. Third, the horse will lose skin
sensation in the back half of its foot but probably loses all
or most of its sole sensation. However, the horse will always
know where the foot is. The foot should then be protected by
using a pad.
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