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A full lameness examination should be

performed which may include lunging,

observation under saddle, flexion and

extension and frog pressure tests. A physical

examination including the use of hoof testers

will also be carried out. Your vet may at this

point be highly suspicious of foot pain. The

location of pain within the foot can be

evaluated with the use of nerve blocks and

blocks of the coffin joint and navicular bursa.

If pain in the foot is confirmed, a radiographic

examination will be performed next. After shoe

removal and foot preparation, numerous x-ray

views of the foot will be taken to check for the

presence, number, shape, size and location of

specific degenerative changes and an

assessment will be made of bone definition

and regularity, and new bone growth.

Bone scans (scintigraphy), CT or MRI scans

may also be performed. MRI will be most

commonly used to more accurately assess

the tendons, ligaments and give us vital

information about the bone that can’t be seen

on x-ray, such as bone necrosis, fibrosis or

haemorrhage. Bursoscopy is occasional done

to directly see the fibrocartilage at the back of

the navicular bone and the deep digital flexor

tendon and any adhesions between them.

Corrective farriery is the mainstay of

treatment with our first goal being to get the

foot back in perfect balance. As some cases

can have ‘long toe, low heel’ conformations

and others could have small upright boxy

feet, there is no single way to trim and

shoe navicular disease cases. Every horse

is an individual.

We can say however that we want to ensure

a straight hoof pastern axis and correct

side-to-side balance. We want plenty of

support for the caudal heel to expand and

contract, and nails shouldn’t be put too far

back. The break over point should be as far

back as possible to encourage early take

off and reduce the stress on the navicular

apparatus. Your vet and farrier may decide

together that egg bar shoes, natural balance

shoes or heart bar shoes are appropriate.

They may decide your horse needs

graduated shoes or wedges or possibly just

a wide web shoe with a little extra length.

Solar packing may be advised.

Additional medical treatments may be used.

This may include anti-inflammatory painkillers

such as phenylbutazone or steroids may be

injected directly into the navicular bursa. Your

vet may recommend bisphosphonate drugs,

such as clodronate, which helps to reduce

further weakening of the navicular bone.

Isoxuprine can be used as a vasodilator to

improve blood flow to the foot although this

treatment has gone somewhat out of fashion.

Short-term pain relief can be obtained by

using extracorporeal shock wave therapy

(ECSWT).

In advanced cases, chemical or surgical

intervention of the pain conducting nerves

may be warranted. Freezing the nerves

with liquid nitrogen or injecting alcohol,

sarapin or even cobra venom around the

nerves to the foot to alleviate pain, have

been reported. Surgical procedures can be

performed involving severing supporting

ligaments (desmotomy). Pain relief can also

be achieved by directly cutting the nerves

(neurectomy) to the heel/foot. This can

give up to 18 months relief before sensation

appears to come back.

NAV I CULAR D I SEASE

SUMMER 2015 ISSUE

EQUINE MATTERS

4

Note the front wall, heel and pastern are

all parallel

Radiography has historically been the

primary method of diagnosing cases of

navicular disease

Solar packing provides support and reduces

the stress on the navicular apparatus

Dynamic and static foot balance should be

assessed and treated

X-ray guided medication of the navicular

bursa

Treatment options for navicular

disease

Diagnosis

A broken-back hoof pastern axis can cause

low grade cumulative injury