Problems in the navicular region of the equine digit have been plaguing horses since before humans, it appears. Today we are beginning to understand more about how to help horses, but it is a very frustrating and common problem that although usually manageable,will not go away. Most agree that a horse must be allowed to be free of its stall most of the time.

Definition:

There are many names and a long, long history for what is efficiently called cauldal heel pain or disfuntion. It is a common lameness affecting mostly forelimbs of predimantly male(1) Quarter horses and Thorobreds. It is rarely seen in ponies or Arabians. It involves degeneration or accelerated remodeling of the navicular bone and related structures.

There are three main forms – Articular: coffin joint and articular cartilage. Tendinous: navicular bursa and deep flexor tendon. Ligamentar: impar (distal) and collateral (suspensory) navicular ligaments.

Anatomy:

There is a lot of anatomy in such a very small (relative to the mass of the horse), constant high pressure area:

Vascularity under palmar flexor cortex
Deep digital flexor tendon (DDFT)
Navicular bone (Distal sesamoid)
Fibrocartilage
Marrow cavities
Navicular bursa
Impar ligament (dnl) distal navicular ligament
Collateral ligament (slnb)
Coffin joint (distal interphalangeal joint)

Clinical signs:

Often, a horse presents with a history of progressive, chronic, unilateral or bilateral forelimb lameness with a grade of 1-2 out of 5. It could also have a sudden acute onset. It is likely the lameness will be asymmetric (in these cases, sometimes one hoof, sometimes another will be most lame). Short strides. Toe first landing. Bruising in the toe from a toe first landing. Worse on circles making it then easily confused with a shoulder problem. Mismatched hooves. Pain response to the hoof testers in the navicular area. A saw horse stance if all four hooves are affected. Signs fluctuate.

Causes:

Long toe/low heel due to inherited conformation (poor choices in breeding priorities), handedness (diagonal preference), improper hoofcare, over-exertion of an under-fit horse, stabled performance style care (meaning: stalled and ridden…stalled and ridden…)

Treatment:

Mechanical: Raise angle to reduce stress on palmar flexor cortex. Use mechanics of hoof or shoe to obtain a proper base of support and breakover. Therapeutic shoes are usually required, especially in long toe low heel cases.
Management: Rest while inflammation is present (about 3 weeks), then slow and steady re-conditioning with steady turnout.
Surgical: Neurectomy.
Drugs: Isoxsuprine Hydrochloride is a vasodilator and is attributed to 60-80% success in improving lameness.

Diagnostics:

Hoof testers, radiography, scanning electron microscopy, scintigraphy (nuclear imaging).

Navicular Disease: Researchers Identify Potential Genes Involved

Originally published on TheHorse.com

A team of German researchers might have pinpointed the genes responsible in part for the development of navicular disease as the result of a study of Hanoverian Warmbloods.

Read more: http://www.bloodhorse.com/horse-racing/articles/60433/navicular-disease-researchers-identify-potential-genes-involved#ixzz18q9gw4ld

Kentucky Horseshoeing School Therapeutic Module 1. Rood and Riddle.

You may want to read the introduction article here.

Dr. Scott Morrison of Rood and Riddle and staff.

Presentation: Heel pain. Club feet, laminitis (and their similarities). Low (compressed) heels. Quarter cracks. Keratoma. Infections. Foal and mature limb deviations.

Some of the notes are:

Heel pain:

High heels:

Poor [...]